Neonatal Respiratory Care Handbook

55461_FMXx_ttlpg.indd 1 Neonatal Respiratory Care Handbook Elgloria A. Harrison, MS, RRT-NPS Associate Professor Depar...

Author: Elgloria A. Harrison

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Neonatal Respiratory Care Handbook Elgloria A. Harrison, MS, RRT-NPS Associate Professor Department of Nursing and Allied Health Respiratory Therapy Program University of the District of Columbia

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World Headquarters Jones and Bartlett Publishers 40 Tall Pine Drive Sudbury, MA 01776 978-443-5000 [email protected] www.jbpub.com

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Jones and Bartlett’s books and products are available through most bookstores and online booksellers. To contact Jones and Bartlett Publishers directly, call 800-832-0034, fax 978-443-8000, or visit our website, www.jbpub.com. Substantial discounts on bulk quantities of Jones and Bartlett’s publications are available to corporations, professional associations, and other qualified organizations. For details and specific discount information, contact the special sales department at Jones and Bartlett via the above contact information or send an email to [email protected]. Copyright © 2011 by Jones and Bartlett Publishers, LLC All rights reserved. No part of the material protected by this copyright may be reproduced or utilized in any form, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without written permission from the copyright owner. The author, editor, and publisher have made every effort to provide accurate information. However, they are not responsible for errors, omissions, or for any outcomes related to the use of the contents of this book and take no responsibility for the use of the products and procedures described. Treatments and side effects described in this book may not be applicable to all people; likewise, some people may require a dose or experience a side effect that is not described herein. Drugs and medical devices are discussed that may have limited availability controlled by the Food and Drug Administration (FDA) for use only in a research study or clinical trial. Research, clinical practice, and government regulations often change the accepted standard in this field. When consideration is being given to use of any drug in the clinical setting, the health care provider or reader is responsible for determining FDA status of the drug, reading the package insert, and reviewing prescribing information for the most up-to-date recommendations on dose, precautions, and contraindications, and determining the appropriate usage for the product. This is especially important in the case of drugs that are new or seldom used. Additional photographic and illustration credits appear on pages 261 and 262, which constitute a continuation of the copyright page. Production Credits Publisher: David Cella Associate Editor: Maro Gartside Production Assistant: Tina Chen Marketing Manager: Grace Richards Manufacturing and Inventory Control Supervisor: Amy Bacus

Composition: Publishers’ Design and Production Services, Inc. Assistant Photo Researcher: Carolyn Arcabascio Cover Design: Scott Moden Printing and Binding: Imago Group Cover Printing: Imago Group

Library of Congress Cataloging-in-Publication Data Harrison, Elgloria A. Neonatal respiratory care handbook / Elgloria A. Harrison. p. ; cm. Includes bibliographical references and index. ISBN 978-0-7637-5546-1 1. Respiratory insufficiency in children—Handbooks, manuals, etc. 2. Newborn infants—Diseases—Handbooks, manuals, etc. I. Title. [DNLM: 1. Lung Diseases—therapy. 2. Child. 3. Infant. 4. Lung Diseases—diagnosis. WS 280 H318n 2009] RJ312.H37 2009 618.92'01—dc22 2009024206 6048 Printed in Hong Kong 13 12 11 10 09 10 9 8 7 6 5 4 3 2 1

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Dedication

This book is dedicated to my daughter, Delisie, who turned out to be a wonderful, funny comedienne; to Moma, Lola, and Misty, my furry companions; to my family, who has always been in my corner; to my neighbor, Vanessa, who has been a source of encouragement throughout this project; to my mentor, Dr. Felecia Moore Banks, who paved the path for this project; and to my colleagues at the University of the District of Columbia, who have been my cheering squad. I could not have done this book without you. Special thanks to Dr. J. Bert Bunnell and Bunnell Incorporated.

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Contents

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii Contributor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix Chapter 1

Acute Respiratory Distress Syndrome (ARDS) . . . . . . . . . . . . . . . . . . . . . . 1

Chapter 2

Infant Respiratory Distress Syndrome (IRDS) . . . . . . . . . . . . . . . . . . . . . . 37 Jacqueline Haymon Smith, BS, RRT-NPS

Chapter 3

Asthma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Chapter 4

Chronic Lung Disease of the Newborn . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

Chapter 5

Cystic Fibrosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

Chapter 6

Upper Airway Inflammatory Diseases . . . . . . . . . . . . . . . . . . . . . . . . . . . 119

Chapter 7

Bronchiolitis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

Chapter 8

Air Leak Syndromes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149

Chapter 9

Congenital Heart Disease . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187

Chapter 10 Neuromuscular Diseases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219 Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 Credits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261

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Preface “Let us dare to read, think, speak and write.” John Adams, 1765

When considering what type of book to write, my mind flooded with the great torrent of knowledge already available on the subject of neonatal and pediatric respiratory care. As I continued to reflect on the everyday job of a respiratory therapist in a neonatal intensive care unit (NICU) or a pediatric intensive unit (PICU), it occurred to me that a concise guidebook that actually provides both illustrations and text on how to assemble some of the most complex respiratory equipment and includes explanations for the purpose of this equipment would be beneficial to a respiratory therapist. There are a number of books on respiratory therapy equipment and even more books on the pathophysiology and management of the neonatal and pediatric patient; this book does not attempt to replace any of those books. This little respiratory compilation is a handy pocket-size guidebook, one that is easy to understand, with an excellent display of images, designed with the new respiratory therapist or the respiratory student in mind. My goal is to share with the reader my experience in the NICU and PICU, where it is necessary to understand the array of equipment that has been developed for this patient population. In the NICU and PICU world, we learn quickly how to adapt this equipment to the neonate or pediatric patient. Of recent years, manufacturers have been more responsive to those of us who work in these areas: there has been a proliferation of equipment designed just for the neonate and the pediatric patient. Having said this, it becomes an ongoing challenge for educators, whether in academia or the hospitals, to keep up with the maze of available equipment and to be able to ensure competency of each student or new graduate respiratory therapist. This task can sometimes be overwhelming; thus this book will be a welcome addition to an educator regardless of the setting. It is my desire that a new respiratory therapist graduate will use this book as a reminder of how to set up equipment in the NICU and

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Preface

PICU and that this book will enable the respiratory therapist to become more proficient in the NICU and PICU areas. I might add that this book is not designed to be a substitute for an actual orientation or a class on neonatal/pediatric respiratory care but will simply add to the respiratory therapist’s current knowledge base.

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Contributor

Jacqueline Haymon Smith, BS, RRT-NPS Clinical Manager of Respiratory Care Georgetown University Hospital Washington, DC

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Chapter

1

Acute Respiratory Distress Syndrome (ARDS) Chapter Outline DEFINE • Define acute lung injury/acute respiratory distress syndrome (ALI/ARDS) • Discuss whom ALI/ARDS affects DESCRIBE • Describe the clinical presentation of ALI/ARDS • Describe the etiology of ALI/ARDS DISTINGUISH • Distinguish ALI/ARDS from congestive heart failure (CHF) • Distinguish the phases of ALI/ARDS • Distinguish the phases illustrated in this clinical case review RESEARCH • Relevant research on ALI/ARDS TREATMENT • Treatment options in the care of ALI/ARDS patients • Respiratory therapist role in the management of ALI/ARDS

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Key Terms Acute lung injury (ALI) Acute respiratory distress syndrome (ARDS) Extracorporeal membrane oxygenation (ECMO) Heliox administration High-frequency oscillatory ventilation Infant respiratory distress syndrome Inhaled nitric oxide Lung protective strategy Mechanical ventilator Partial liquid ventilation Prone positioning Recruitment maneuver

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Chapter 1 Acute Respiratory Distress Syndrome (ARDS)

DEFINE

Acute lung injury and acute respiratory distress syndrome (ALI and ARDS) is a syndrome marked by severe lung injury that causes an acute hypoxemia respiratory failure requiring high levels of oxygen and positive end-expiratory airway pressure (PEEP) therapy. Egan’s Fundamentals of Respiratory Care makes a distinction between ALI and ARDS: the latter is classified as more serious, leading to other organ failures.1,2,3 Khemani and colleagues suggest the definition used to establish ARDS in adults is valid in establishing the diagnosis in children.4 According to Pilbeam and Cairo, approximately 75% of all ALI cases develop into ARDS.2 Figure 1-1 highlights recommended criteria for ALI and ARDS. The American European Consensus Conference (AECC), who was charged with the development of a standardized definition of ARDS, officially defined it as follows:5 “A syndrome of inflammation and increasing permeability that is associated with a constellation of clinical, radiologic, and physiologic abnormalities that cannot be explained by, but may co-

Inflammatory response caused by sepsis, aspiration pneumonia, multiple trauma, that facilitates severe hypoxemic respiratory failure

Acute lung injury Acute onset PaO2 /FiO2  300 mm Hg Complete white-out on chest x-ray No evidence of CHF

ARDS Acute onset PaO2 /FiO2  200 mm Hg Complete white-out on chest x-ray No evidence of CHF Figure 1-1 Criteria Chain for ALI and ARDS

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exist with, left atrial or pulmonary capillary hypertension” and “is associated most often with sepsis syndrome, aspirations, primary pneumonia, or multiple trauma and less commonly with cardiopulmonary bypass, multiple transfusion, fat embolism, pancreatitis and others.” DESCRIBE

Clinical presentation of ARDS is characterized as a severe ventilation perfusion mismatch that leads to significant respiratory hypoxemic failure. ALI/ARDS can present in any number of ways. What follows are a few examples of risk factors common in children with ARDS. This list represents only a snapshot of the many causes of ARDS. • • • • • • • • • •

Pneumonia Aspiration pneumonia Shock Multiple trauma Head injury Near drowning Extensive burns Oxygen toxicity Narcotic drug overdose Pulmonary contusion

Clinical Signs • • • • • • •

Increase in respiratory rate Retractions Dyspnea Pulmonary edema Bilateral crackles noted on auscultation Respiratory alkalosis secondary to hyperventilation Worsening arterial blood gases as the disease progressively leads to respiratory insufficiency • No response to oxygen therapy with worsening lung compliance • Chest x-ray showing diffuse bilateral infiltrates (complete whiteout)

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DISTINGUISH

Care must be made to distinguish ARDS from congestive heart failure (CHF) because signs and symptoms of ARDS can be similar in patients with CHF. Signs of CHF include the following: • • • •

History consistent with heart failure Enlarged heart on chest x-ray Pleural effusion Pulmonary capillary wedge pressure of greater than 18 mm Hg1

Clinical Case Review Good clinical cases are excellent models to demonstrate the phases of ARDS. This case demonstrates the four phases of ARDS in a child with a suspected chemical toxin inhalation. A 12-year-old boy was admitted to the pediatric intensive care unit with a high fever and uncontrollable coughing, as reported by the child’s mother. Prior to these events the boy had been healthy. Mother reports that her son went to play at a park near their home. She noticed that across the street from the park a demolition construction crew was working. The crew was removing an old housing project that had been abandoned. Mother said she cautioned her son to stay clear of the construction crew and then left her son in the park to play while she returned home. An hour later the son appeared at home, but immediately went to his room. The mother thought it was odd that her son would go to his room because he is very active. Mother followed to her son’s room to find him in bed complaining of being tired. Mother felt his head, which appeared warmer than usual, so she took his temperature. The result was 39.9 centigrade. Mother immediately rushed her son to the emergency room at their nearby hospital. During the ride to the hospital the son complained that he was having a hard time breathing. Mother could hear her son in the back seat of the car having what she described as a “coughing fit.” Mother made attempts to calm her son during the ride, but her only hope was to get her son to the hospital as quickly as possible. Mother reports no history of asthma or cardiac disease

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with her son or anyone in the family. Apart from the above history, there were no other significant health issues with her son. Initial Vital Signs upon Arrival to the Emergency Room Phase 1 • 4 hours since the child was in the park • 12-year-old boy appropriate height and weight for his age • Observed shortness of breath, respiratory rate: 30 to 35 breaths per minute • Heart rate: 120 to 130 bpm • SaO2: 95% on room air • ABG results: relatively normal with PaO2 84 mm Hg and PaCO2 37 mm Hg • Retractions observed • No nasal flaring • Breath sounds: diminished airflow throughout lung fields • Capillary refill: less than 3 seconds • Chest x-ray appears normal • Child still able to speak, although sentences are slightly choppy From this assessment, it appears that this 12-year-old is in phase 1 of ARDS. Kenneth Whitaker, in his pediatric textbook, divides ARDS into four phases, in which phase 1 occurs within 1 to 12 hours of the initial injury.6 It is not clear from the child’s history as to the direct cause, but one could surmise that the child inhaled chemical toxins while in close proximity to an old building being demolished. In phase 1 of ARDS, blood gas values and chest x-ray may look normal, yet clinically the patient may show evidence of inadequate ventilation and gas exchange. Respiratory Therapist Initial Response • 100% nonrebreather mask to deliver as close to 100% FiO2 as possible • Close monitoring for signs of increasing respiratory distress • Preparation for possible intubation

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Phase 2 The child has progressed to severe respiratory distress with the following parameters: • • • • •

Respiratory rate: 40 to 50 breaths per minute Heart rate: 120 to 130 bpm Breath sounds: crackles throughout Chest x-ray: some bilateral infiltrates Arterial blood gas shows a respiratory alkalosis with a mild hypoxemia (pH 7.48 PaCO2 32, PaO2 68 HCO3 26 on 100% nonrebreather mask)

Phase 2 occurs 12 to 24 hours after the initial lung injury, and this is really the time to begin aggressive treatment.6 At this point a decision is made to intubate this child. Although the arterial blood gas shows a respiratory alkalosis with a mild hypoxemia, it is in the child’s best interest that the intubation is done now. It is not surprising that a few hours before the decision to intubate, the child appeared to be in phase 3 of ARDS.6 Understanding and interpreting arterial blood gases is critical in the management of children with ALI/ARDS. For example, the above blood gas shows a respiratory alkalosis with mild hypoxemia, which is evident of a child hyperventilating secondary to maintaining adequate gas exchange. When this child shows signs of fatigue, respiratory acidosis becomes evident, which is a direct correlation to increasing carbon dioxide production secondary to decreased or ineffective respiratory efforts. Hypercarbia respiratory failure, acute pH less than 7.25, and acute PaCO2 greater than 55 is the standard used in the decision to intubate. As we will soon learn, this child has met the criteria for intubation. An in-depth discussion of arterial blood gas interpretation is beyond the scope of this guide book; however, there are a number of excellent respiratory books with chapters devoted to this topic. Egan’s Fundamentals of Respiratory Care, the chapter on arterial blood gas, is a good place to start.1 Phase 3 • The boy can hardly speak and is breathing very shallowly. • He is becoming more lethargic.

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• His arterial blood gas shows a respiratory acidosis with now a moderate hypoxemia. Respiratory Therapist Follow-Up Response Respiratory therapist recommends intubation. Child is intubated with a #6 endotracheal tube. Chest x-ray showed endotracheal tube placement in good position. Chest x-ray also shows lungs with noticeable diffuse bilateral infiltrates. This concurs with phase 3 of ARDS: • Severe respiratory acidosis • Severe hypoxemia • Evidence of diffuse bilateral infiltrates A sample of ventilator settings: Mode: Assist control Rate: 16 Vt: 4 to 6 ml/kg based on ARDSnet protocol FiO2 initial: 100% PEEP: Titrate PEEP levels to maintain the lowest PEEP to keep lungs open at the end of exhalation while assuring an acceptable PaO2 See Table 1-1 for initial ventilator settings. Considering all aspects of ARDS, it is necessary to be on the alert for changes in airway resistance and lung compliance while being ventilated. Avoid air trapping and auto-PEEP as much as possible. During the child’s stay in the PICU, there were many ventilator changes as a result of worsening ventilatory failure, conclusive evidence of phase 4 ARDS. Phase 4 • • • • • •

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Worsening respiratory failure Worsening arterial blood gases Multiple organ failure—the child now has acute renal failure Significant fibrosis of the lung parenchyma Severe ventilation and perfusion mismatch Has been on the ventilator for more than 2 weeks

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Table 1-1 Suggested Initial Settings for Mechanical Ventilation Mode

Assist control SIMV with pressure control and pressure support APRV (These are three examples—your ventilator may have other modes that will work equally as well.)

Rate

12 to 20 breaths/minute

Tidal volume

4 to 6 ml/kg or 5 to 7 ml/kg based on ideal body weight and your hospital specific protocol7,8

Oxygen

FiO2 to keep SaO2 greater than 90%

PEEP

Titrate PEEP levels to maintain the lowest PEEP level to keep lungs open at the end of exhalation while assuring an acceptable PaO2 (see Table 1-4).

Flow

Some ventilators may automatically adjust flow; if not, then flow should be adequate to meet the patient inspiratory flow demand.

I:E ratio

1:2 If using APRV, the I:E ratio maybe inversed.

Inspiratory time

0.8 to 1 second when using either AC or PC. This may be different if using APRV.

Trigger or sensitivity

Flow trigger 1 to 3 L/min or pressure trigger 0.5 cm to 2 cm H2O

In just a little under 48 hours, significant changes have occurred to this child’s lung tissue, making the lungs stiffer and causing a major ventilation and perfusion mismatch. So no matter how you look at it, ARDS is a force to be reckoned with. It is most important that the respiratory therapist have an understanding of the big picture of ARDS. This understanding is what makes a respiratory therapist invaluable to the medical team. RESEARCH

Acute respiratory distress syndrome (ARDS), as the literature points out, is a subset of acute lung injury (ALI). For the purpose of this discussion, ALI/ARDS will be used interchangeably to mean one and the same. For all intents, we should really call it “Devastation, Devastation, Devastation,”

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for that is what we see when patients present with ALI/ARDS. Historically, ALI/ARDS has undergone numerous name changes: adult respiratory distress syndrome was one; however, inasmuch as there have been name changes, the research clearly articulates that ARDS has not been selective to adults but to anyone who has a set of lungs. One research study made a distinction between the adult version and the infant version of ARDS. This chapter will focus on the research of children over 1 year old, and Chapter 2 will deal exclusively with infant respiratory distress syndrome of children younger than 1 year of age. Just as there will be overlapping between these two chapters, there will be distinct differences, particularly in the area of treatment. There is much research about ALI/ARDS because, according to the National Heart Lung Blood Institute (NHLBI), the condition affects more than 150,000 persons in the United States annually.3 Other researchers argue that the number is much lower than 150,000: more like 20,000 to 30,000 cases per year.1 Mortality rate is still high, despite the advancement made in the treatment of the disease, and death is still projected at 30% to 40% owing to multiple organ failure.1,3,5,6 ARDS is believed to be a public health crisis costing the United States millions of healthcare dollars.5 Consequently, there is a great interest to fund research to find a cure for ARDS. Interestingly enough, ARDS was identified some 100 years ago; yet, it would be 50 years before we would recognize ARDS as we know it today. Recognition of ARDS was brought into focus around the same time mechanical ventilators became popular and the establishment of intensive care units.9 In 1967, a major study published in Lancet by Ashbaugh et al. described the clinical appearance of adult respiratory distress syndrome. The authors concluded that ARDS was initiated by a number of unrelated events that caused the lungs to behave abnormally. They cited such examples as gastric aspiration, sepsis, blunt trauma, and near drowning, to name a few.2,5 You can find the American European Consensus Conference (AECC) standardized definition of ARDS on page 2 in this book.5 Additionally, ARDS was classified as a subset of acute lung injury, in which both conditions are acute in onset: low arterial hypoxemia that does not respond to oxygen therapy alone, and chest x-rays that show

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diffuse infiltrates.1,2,5 In addition, Miles et al. further define ALI as a PaO2/ FiO2 ratio of 300, in which ARDS’ ratio is 200.1,2,10 Khemani and colleagues agree that the use of the P/F ratio is adequate in defining ARDS and ALI; however, their research showed that using SpO2/FiO2 may also be a reliable method of identifying children with lung injury.4 One thing is clear: ARDS has been studied at length from a variety of perspectives, and yet no cure has been introduced. Most of the research has focused on supportive care to minimize the damage to the lungs, thereby improving overall outcomes. Although patients with ARDS are placed on mechanical ventilators, early research demonstrated that, in fact, the mechanical ventilator may have exacerbated an already injured lung. A number of studies were done to show the effects of various ventilator parameters on lung tissue. In 1994, the ARDS Clinical Research Network (ARDSnet) of the National Heart, Lung, and Blood Institute (NHLBI), part of the National Institutes of Health (NIH), conducted a clinical trial comparing various lung protective strategies.10,11 Low tidal volume (6 ml/kg) was compared to conventional tidal volume or high tidal volume (12 ml/kg). They hypothesized that those in the low tidal volume group would have better outcomes than those in the high tidal volume group. The study showed a significant reduction in mortality for the low tidal volume group. ARDSnet further demonstrated that with the low tidal volume group, there were fewer ventilator days, less multiple organ failure, and less circulating inflammatory markers frequently seen in patients with ARDS.10,11 Whereas the ARDSnet showed success, this was just the beginning of similar studies set out to either confirm or refute the ARDSnet findings. Although the ARDSnet population included mostly adults, Hanson and Flori agree that applying the low-tidal-volume strategy to children with acute lung injury was appropriate because the ARDSnet has proven a successful strategy in several large, multicenter clinical trials.12 A second very important study from the ARDSnet was the use of positive end-expiratory pressure (PEEP) as an alveoli recruitment maneuver.11 PEEP has been the gold standard used to recruit alveoli, decrease oxygen requirement, and improve lung compliance. In 80 of the patients assigned to the high-PEEP group, recruitment maneuvers were performed. These patients were placed on high PEEP of 35 to 40 cm H2O

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for 30-second periods. The researchers found only modest benefit to improving oxygenation while performing the recruitment maneuver. Thus recruitment maneuvers were stopped. Although the ARDSnet did not include high PEEP as a part of their protocol, the researchers cautioned that high PEEP should be reserved as a recruitment maneuver for those patients with a serious oxygen defect that is not responding to current oxygen therapy. Whereas the ARDSnet found only modest benefit, Meade et al. successfully conducted a clinical trial in which they studied 983 ALI/ARDS patients from 2000 to 2006.13 Their protocol, although similar to the protocol used in ARDSnet, used low tidal volumes, recruitment maneuvers, and high PEEP to recruit and open the lung. Unlike the ARDSnet, their recruitment maneuver was started with PEEP of 20 cm H2O, routinely done 4 times a day until the patient was weaned to an FiO2 of 40% or less.13 This group maintained a control group, which followed the ARDSnet protocol, and the experimental group, which was subject to the higher PEEP levels. Their results suggest that there was more hypoxemia and increased FiO2 in the control group, similar tidal volumes in both groups, and higher plateau pressures in the experimental group. Overall, they found more similarities than differences between the groups because the open lung ventilation strategy resulted in no greater mortality than that of the control group. The authors acknowledged there were limitations to this clinical trial: it was difficult to tell whether it was the effect of the higher PEEP, the recruitment maneuvers, or higher plateau pressure that made an impact on mortality. They concluded their findings with the observation of using a multifaceted open lung-protective ventilation strategy as an alternative to the current established low-tidal-volume ventilation strategy.11 Based on their findings, they support the use of higher PEEP levels. The authors readily admit that success of the protocol was owed in part to those clinicians “increasingly comfortable with higher levels of PEEP.” Currently, there are more than 100 clinical trials at various stages funded by the NHLBI to answer these four basic questions about ARDS: (1) What initiated the lung injury? (2) What mediates progression of ongoing lung injury? (3) What causes persistent fibrosis and pulmonary hypertension? (4) What mediates the propagation of injury from the

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lung to other organs.”5,10 Much of the research has focused on ventilator care; however, a few studies worth noting have directed our attention to nonventilator strategies for managing ARDS: (1) surfactant replacement therapy, (2) prone position, and (3) inhaled nitric oxide. The research is clear regarding the benefit of surfactant replacement therapy (SRT) in the neonate, an infant born before 37 weeks, who lack mature surfactant. Moller et al. suggest in their research that the use of bovine surfactant administered intratracheally with continuous mechanical ventilation showed improvement in oxygenation in older children; however, this study found improvement in patients who did not have pneumonia and already had a P/F ratio that was greater than 65.14 Although surfactant therapy has proven successful for the neonate with infant respiratory distress syndrome, meconium aspiration syndrome, and other conditions comparable to ARDS, there is a need for randomized clinical trials in the pediatric age group evaluating administration of SRT for the treatment of refractory hypoxemia. Prone position has been shown in the adult population to improve lung compliance and promote better gas exchange. Relvas and colleagues report that in pediatric patients with ARDS, prone position for 18 to 24 hours a day showed significant improvement in oxygenation compared to prone position for less than 12 hours per day.15 Prone position has been shown to promote oxygenation in the following ways: • Better diaphragmatic movement • Recruitment of formerly collapsed dependent lung regions • Rerouting pulmonary blood flow, enhanced drainage of airway secretions • Increased negative pleural pressure15 Finally, the use of inhaled nitric oxide in children with ARDS may show promise in the treatment of refractory hypoxemia. Inhaled nitric oxide is an endogenous endothelial-derived mediator that causes smooth muscle relaxation.16 Baldauf et al. were not convinced of the benefits of iNO because studies of its use were small and not clinically impressive. The aim of their study was to develop an analytic tool that would validate the responsiveness to the use of iNO in children. Nineteen children were enrolled in their study. Controlling for known variables, they

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observed the change in mean pulmonary arterial pressure and P/F ratio as a measurement of significance. They report an improvement in both parameters.16 This study concludes that when clinicians report observable improvement in oxygenation with the administration of iNO, it is reported using an instrument that would validate their findings and these are not purely speculative or anecdotal comments. Although there are more unanswered questions than answered ones, it is comforting to know that research is ongoing and that soon answers may be forthcoming. But until then, we concentrate on supportive care. There are a number of treatment options that are used for ALI/ARDS patients. The next section will discuss how respiratory therapists play an integral role in the management of patients with ARDS. TREATMENT

The key to improved mortality and reducing morbidity is early recognition of a child with ALI or ARDS. Early recognition results in early treatment geared toward improving outcomes. The role of the respiratory therapist will be many: from the emergency room to the pediatric intensive care unit. Because ventilation and oxygenation are overriding factors in the management of ARDS patient, the job of the respiratory therapist will be to help develop a plan that will promote adequate ventilation while improving oxygenation. Believe me, this is no small feat. A well-thought-out management plan for patients with ARDS includes the entire medical team. There are a number of approved therapies for the treatment of ARDS. Table 1-2 highlights some of the approved modalities that a respiratory therapist would use to manage a child with ARDS. Following this chart is a detailed discussion of the modalities and illustrations of the actual equipment setup. Discussion of Each Treatment Modality Conventional Mechanical Ventilation Recommendations from the ARDSnet for mechanical ventilation suggest a lung-protective strategy that employs low tidal volumes, higher rates, and an FiO2/PEEP combination that will facilitate adequate oxygenation. Although there is ongoing debate with regard to the ARDSnet findings, it remains the standard of

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Table 1-2 Treatment Options for the ARDS

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Type of Therapy

Application

Conventional ventilation Mode of ventilation Assist control

ARDSnet suggests tidal volume between 5 to 7 ml per kg of ideal body weight.7,8 It might be appropriate in your PICU to use 4 to 6 ml/kg. The protocol established in your PICU will dictate. Assist control FiO2 to keep SaO2 greater than 92% Optimal PEEP: see next section. Ventilator rate 12–20 using your arterial blood gas as your guide. Some ventilators are equipped with end tidal CO2 manometer, which is useful in evaluating exhaled CO2.

Optimal level of PEEP

Titrate PEEP levels to maintain the lowest PEEP level to keep lungs open at the end of exhalation while assuring an acceptable PaO2.

Pressure control ventilation (PCV): consider this mode if you are unable to control the peak inspiratory pressure using volume control mode as described above.

Maximum peak inspiratory pressure: a starting point should be the plateau pressure from previous mode. The goal is to remain below 30 cm H20; however, 30 to 35 cm H2O may be required to maintain adequate ventilation. Caution: monitor closely for changes in hemodynamic stability because the higher the peak pressure, the more likely to impede venous return.

Airway pressure release ventilation (APRV)

Used most often in adult ventilation when either assist control or pressure control has failed. This mode of ventilation requires the patient to breathe spontaneously at two different pressure levels: a high pressure and a low pressure. Frequency is set by setting the high time and low time.

High-frequency oscillatory ventilation (HFOV)

HFOV uses smaller tidal volumes (less than 5 ml/kg), fewer variable airway pressures, and rates up to 300 breaths per minute.

Prone positioning

Placing a patient on his or her stomach in a head-down position has been shown to improve the ventilation perfusion mismatch so often seen in ARDS patients.

Extracorporeal membrane oxygenation (ECMO)

This is a technique developed that is similar to the heart-lung bypass machine used in adults. In children it has been used as a rescue therapy in the early phase of ARDS. This therapy is used most often with patients who have life-threatening ARDS when other therapies designed to improve oxygenation have failed.

Inhaled nitric oxide (iNO)

Nitric oxide is a colorless, odorless gas that was found to be a selective pulmonary vasodilator in patients with pulmonary hypertension.

Heliox administration

The literature has demonstrated that heliox has shown to improve oxygenation when used in combination with HFOV for patients with ARDS.

Partial liquid ventilation (PLV)

Perfluorocarbon has the ability to dissolve large volumes of oxygen and CO2 at atmospheric pressure, thereby reducing surface tension in lungs that are surfactantdeficient.

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care at this time. The pinnacle of the ARDSnet protocol is the use of low tidal volumes (6 ml/kg of predicted body weight). The selection of the tidal volume can be done based on the patient’s actual weight.7,8 The selection of your ventilator setting is not under debate: the ultimate goal is to choose a volume that is appropriate, delivers adequate chest rise, avoids alveolar overdistention, and allows a chest x-ray that demonstrates no further harm to the lung tissue based on your ventilator settings. Keep in mind that although the use of the low tidal volume strategy is a lung protective strategy, some patients’ arterial blood gas will inevitably show a respiratory acidosis. The use of this strategy is called permissive hypercapnia, and in some patients pH levels as low as 7.10 to 7.20 have been tolerated.17 Permissive hypercapnia is tolerated well in young people and those with few cardiovascular abnormalities. As a subset to conventional ventilation, airway pressure release ventilation (APRV) has been suggested as a mode of ventilation that has promise in the treatment of patients with ALI/ARDS. This mode allows a patient to breathe spontaneously at two separate pressure levels. Some authors suggest that APRV is similar to breathing at two continuous positive airway pressures (CPAP) in which the higher level of CPAP helps support the tidal volume while the subsequent drop to the lower CPAP level acts to reduce the mean airway pressure. The frequency is controlled by time: the expiratory time is short, which aids improved functional residual capacity while promoting an inverse inspiratory and expiratory ratio. One thing to keep in mind—this mode is pressure augmentation, and so as with all pressure generated ventilation, similar hazards exist. The advantages of this mode are decreased need for sedation, patient ability to control spontaneous ventilation, and overall better patient-ventilator synchrony. Figure 1-2 shows two different types of conventional mechanical ventilator with APRV capabilities. Although pressure breathing has significant benefits in ALI/ARDS ventilator management, PEEP therapy has made the most gains. This was evident in the ARDSnet study and continues to this day in clinical practice, so a word about the importance of PEEP is in order. Although PEEP

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Figure 1-2 Conventional ventilator with APRV capabilities

has its drawbacks, the following are some of the benefits for ALI/ARDS patients using PEEP: • • • • •

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Improved intrapulmonary shunting Improved functional residual capacity Improved pulmonary compliance Improved dead-space ventilation ratio Improved work of breathing

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17

Understanding PEEP will crystallize the lung recruitment maneuver. Priestly and Helfaer describes a recruitment maneuver as a sustained increase in airway pressure with the goal of opening collapsed lung tissue.18 Recruitment is of particular importance when using low tidal volumes and low levels of PEEP. The ARDSnet proposed that very high levels of PEEP be used over 30 to 40 seconds, whereas other researchers proposed that slightly lower PEEP levels be used for lung recruitment. Facility-specific protocol on lung recruitment maneuver will be the best guide for the respiratory therapist when suggesting the need for lung recruitment. High-Frequency Oscillatory Ventilation (HFOV) High-frequency oscillatory ventilation (HFOV; see Figure 1-3) has been shown to reduce mortality and improve oxygenation in ARDS patients if used early in the disease process. The operative words here are “used early.” This mode has been demonstrated in the pediatric patient and is currently approved by the Food and Drug Administration (FDA) as an alternative to conventional ventilation. According to William Miles and his group, HFOV has been studied in infants comparing HFOV and conventional ventilation (CV), and results show improvement in oxygenation, reduced ventilaTable 1-3 PEEP/ FiO2 Combination Used in the ARDSnet Mechanical Ventilation Protocol FiO2

PEEP

0.3

5

0.4

5–8

0.5

8–10

0.6

10

0.7

10–14

0.8

14

0.9

14–18

1.0

18–24

Note: Settings are from the ARDSnet trial and indicate the required FiO2 to keep oxygen saturation above 90%. This table is important because it demonstrates titrating of PEEP and FiO2 up or down to get the desired PaO2. This is best done in connection with a PEEP trial in which the ideal PEEP will be one that has the best PaO2 in relation to PaCO2, compliance, cardiac output, mean arterial pressure, and mean pulmonary artery pressure.

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Figure 1-3 HFOV

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tor-associated lung injury, decrease in mortality, and fewer mechanical ventilator days.10 Although HFOV has been studied extensively in infants and children, it has not garnered the attention in the adult population with ARDS. In fact, there have been only a few randomized control studies as reported by Miles and others. The clinical trials that were reviewed did show that HFOV is a safe and effective mode of ventilation for the treatment of ARDS in adults.10 How Does HFOV Operate? HFOV uses smaller tidal volumes and less variable airway pressures. This prevents the constant opening and closing shearing forces of lung tissue as seen with conventional ventilation. HFOV is designed to keep the alveoli in an open state, so as alveoli are opened and remain open, the gas moves around the lung tissue seeking to open as many closed alveoli. The HFOV gas distribution mechanism ventilates at very fast rates and very small tidal volumes. Figure 1-3 illustrates the HFOV Sensormedic 3100B. When you look at the unit, you will notice that there are no traditional knobs that are most familiar to us as respiratory therapists, yet the principles of ventilation and oxygenation are very clear. If you understand oxygenation as a function of mean airway pressure, and ventilation as a function of amplitude, then you have got it. Unlike conventional ventilation, delivery of the gas happens in both inspiration and expiration. Where we understand exhalation to be passive in our conventional ventilator, it is active in HFOV. Higginson, used the words of Cairo and Pilbeam to describe HFOV:19 Such a system will incorporate an electronic control circuit, or square-wave driver, which powers a linear drive motor. This motor consists of an electrical coil within a magnet, similar to a permanent magnet speaker. When a positive polarity is applied to the square-wave driver, the coil is driven forward. The coil is attached to a rubber bellows, or diaphragm, to create a piston. When the coil moves forward, the piston moves toward the patient airway, creating the inspiratory phase. When the polarity becomes negative, the electrical coil and the attached piston are driven away from the patient, creating an active expiration.

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A good way to remember how HFOV works: the more the pistons are displaced that create the oscillations (called amplitude) the bigger the tidal volumes delivered to the patient. Now that we have an understanding of how the oscillator works on the inside, let’s discuss each component that simulates ventilator parameters. Oxygen 1. Oxygen Blenders—Most HFOV units are accessorized with oxygen

blenders, allowing you to control your fraction of inspired oxygen to the patient. 2. Mean Airway Pressure—This knob allows you to adjust the mean airway pressure in order to improve oxygenation. It is recommended to start your mean airway pressure 4 to 5 cm H2O higher than the MAP of the conventional ventilator settings. Example, if your MAP on conventional ventilation is 25 cm H2O, then you might start with 29 to 30 cm H2O to achieve an open lung. It goes without saying that if there is evidence of hemodynamic instability, then it is prudent to reduce the MAP by 2 to 3 cm H2O, or at least to the MAP on the conventional ventilator settings. 3. Bias Flow—As with all ventilators, there must be a knob that adjusts the flow of gas delivered to the patient. The MAP knob is dependent on the bias flow. In fact, you must adjust your bias flow to also adjust your MAP. Ventilation 1. Frequency—This is controlled by your hertz (Hz). One hertz is

equal to 60 breaths per minute, and 15 Hz equals 900 breaths per minute (pretty darn fast). Recommended starting Hz is as follows:

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Patient

Weight

Hz

Infant Infant/child Older child

Under 3 kg 3 kg or greater 30 kg or greater

15 Hz 10 Hz to 15 Hz 6 Hz to 10 Hz

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What you soon recognize is the bigger the child, the less the Hertz, and the more the expected delivered volume of gas. Remember: A big change in frequency will have a dramatic change on both your amplitude as well as your MAP—think carefully when making a big Hz change. 2. Power—This controls chest excursion, which we call “the wiggle factor.” A good rule of thumb is to see the wiggle all the way to the belly button: that’s a good chest wiggle. If you lose the wiggle, it could mean that you have a displaced the endotracheal tube or there is an obstruction to gas flow. Your ability to hear breath sounds will be replaced with the sound of the piston on the ventilator, so you must adjust your hearing to the sound, the depth, and the pitch of the HFOV. If any of those change, then you can determine that there has been a change in breath sound. Increase the power and you increase the wiggle; decrease the power and you decrease the wiggle. Some centers recommend a starting setting of “2.” Your PICU may have an established protocol, but if not, start with “2.” A change in power will affect your MAP, so you will have to re adjust your MAP to keep it at the setting that is ordered. 3. Inspiratory time—This control is typically set at 33%, which means that 33% of the total time is spent in inspiration: 33% would give you an I:E ratio of 1:2. 50% would give you an I:E ratio of 1:1. When a patient is placed on the oscillator, it is a big deal. Here are some things to consider: 1. The HFOV circuit is an elongated tubing made of highly inflexible

material designed not to bend easily. The tubing should remain in a straight line to assure that the frequency of the sound waves has a clear path to the chest wall. 2. When initiating HFOV, make sure that the child is on a hard surface—avoid beds designed to minimize pressure sores because it is difficult to produce oscillation on such a bed. 3. Before starting HFOV, it is strongly recommended to suction the patient thoroughly; breaking the circuit for routine suctioning is discouraged.

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The literature supports the use of in-line suction catheters as the standard of care as it minimizes the amount of derecruitment required. Very Important: If you must suction, get help. It is better to have two caregivers than just one. 4. Most patients on HFOV will have a properly placed and working arterial line, so monitoring arterial blood gases should never be a problem. If, on the other hand, the arterial line is not available, then noninvasive monitoring with pulse oximetry, and either an end-tidal CO2 monitor or transcutaneous monitor will work perfectly. Inhaled Nitric Oxide In 1987, nitric oxide was found to have some useful benefits in human. Nitric oxide is a colorless, odorless gas that is relatively insoluble in water.20 Researchers discovered that nitric oxide, once considered a toxic pollutant, had some vasodilation properties on lung tissue.20 By 1991, researchers were able to prove that inhaled nitric oxide was a selective pulmonary vasodilator in patients with pulmonary hypertension.20,21,22 Within 2 years, nitric oxide became available to treat patients with acute respiratory distress syndrome; however, its therapeutic use was limited to the pediatric population—or, more precisely, babies with persistent pulmonary hypertension of the newborn (PPHN). At present, inhaled nitric oxide is still the treatment option for PPHN; however, in the case of ARDS, inhaled nitric oxide is used primarily to improve oxygenation for children outside the NICU who do not have PPHN. There have been several studies on the use of nitric oxide in pediatric patients, and the results confirm inhaled nitric oxide’s safety and efficacy in treating PPHN;21,22 however, results from a limited number of studies in the adult population have been inconclusive as to the benefit of nitric oxide for patients with ARDS. Research shows that inhaled nitric oxide can be given in line with the following mechanical devices: high-frequency jet ventilation (HFJV) with iNO (Figure 1-4), conventional ventilation with iNO (Figure 1-5), HFOV with iNO in line with circuit (Figure 1-6), and HFJV with iNO in line with circuit (Figure 1-7). Recently, inhaled nitric oxide has been used

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in medical transport for children suffering from PPHN or potential candidates for extracorporeal membrane oxygenation (ECMO). Griffith et al. in their review found animal studies that suggest inhaling nitric oxide at a concentration of 40 ppm for up to 6 months had minimal pulmonary toxicity.20 Although your PICU/NICU may use its own established protocol, a good starting point for inhaled nitric oxide has been 20 ppm. Because use of inhaled nitric oxide is primarily used for PPHN, similar to what is stated in the literature, iNO has demonstrated immediate results of relaxation to the pulmonary vascular bed for patients other than

Figure 1-4 HFJV

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Ventilator inspiratory port 15 mm 1.0. to 3/8 inch tubing adapter

Ventilator expiratory port

9 mm 1.0. Patient

22 mm/15 mm 15 mm adapter with gas sample tee Patient gas sample line to iNOvent

15 mm 0.0. to 3/8 inch tubing adapter

Heated wire

22 mm/15 mm 22 mm/15 mm adapter To iNOvent delivery system 22 mm/15 mm adapter

Humidifier

Figure 1-5 Conventional ventilator with iNO

PPHN. iNO can be safely used with your conventional adult ventilators, HFOV and HFJV units. The following are respiratory therapist initial recommendation for iNO: • Starting setting for iNO: 20 ppm • Fi02 on the conventional ventilator should be the same for the iNO unit.

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25

22 mm 15 mm

iNO injector module 22 mm 15 mm

iNO patient gas sample line

Humidifier

Figure 1-6 HFOV with iNO

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HFJV

Humidifier

Injector module

Patient jet box

CV Ventilator circuit

iNOvent

Sampling line

Sampling site for iNO

Patient ET tube Life port adapter

Figure 1-7 HFJV with iNO

• Monitor NO2—keep at less than 3 ppm • Routinely check patient methemoglobin every 12 to 24 hours depending on your institution Prone Patient Positioning Placing the patient on his or her belly to improve oxygenation has been heavily touted in the adult intensive care units for the treatment of ARDS for many years. Our PICU prone positioning experience has been limited; however, prone positioning in the NICU is done routinely. Understanding gas exchange and the implication of ventilation to perfusion mismatch will make this point clear. The lungs have more ventilation to the apices, varying amount of ventilation to the middle of the lungs, and less ventilation to the lower regions where perfusion is greatest. So if you turn the patient on his or her belly, and more specifically head down, the

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apices of the lungs will become gravity dependent, which will allow more blood to this area for better perfusion, thus better oxygenation. In 1974, Bryan suggested prone positioning patients on mechanical ventilators; however, his idea was not met with any measurable success. Thirty years later, prone positioning has become one of the treatments for patients with ARDS patients, and, in fact, some medical centers use prone positioning as a routine part of the protocol for ARDS patients.23,24,25,26 Relvas and colleagues conducted a 3-year retrospective chart review of patients admitted to a pediatric ICU with ARDS and placed in a prone position.15 Their objectives were to show that placing pediatric patients in the prone position for more than 12 hours would improve their oxygenation index. In fact, those patients who were placed in a prone position for 18 to 24 hours showed the most improvement in their oxygenation index. This group of researchers recommends the use of prone position, provided the patient does not have any contraindications to the prone position. Relvas and colleagues suggest the following procedures for prone position of a patient: Preparing the Patient • Obtain chest x-ray to assure endotracheal tube placement. • Adequately secure endotracheal tube, pulse oximeter probes, and indwelling catheters. • Move ECG leads to upper arms and hips. • Consider capping nonessential vascular catheters and nasogastric tube. • Suction the oropharynx. • Apply spongy dressing to pressure point area like knees. • Assess the need for a special care bed. • Assign responsibilities to each member of the team responsible for prone positioning of the patient. Placing the Patient in Prone Position • Turn the head and body in unison; patient’s head should face the ventilator. • Assess endotracheal tube and indwelling catheters.

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• Assess the need to suction. • Insert pillows or pads under the shoulders and pelvis. • Flex the arms and position the knees and feet off the bed—use pillow rolls. • Cushion the forehead. • Assure that the patient is adequately sedated and pain controlled. • Assess the need for chest x-ray to reconfirm. • Slightly reposition every 2 hours. • Leave the patient in prone position for at least 20 hours. Contraindication for Prone Position • • • • • •

Increased intracranial pressure Hemodynamic instability despite the administration of vasopressors Unstable spinal cord injuries Recent abdominal or thoracic surgery Open thorax or flail chest Inability to tolerate prone position (modified from Relvas et al.13)

Extracorporeal Membrane Oxygenation Extracorporeal Membrane Oxygenation (ECMO), most often referred in the literature as extracorporeal life support (see Figure 1-8), is a technique developed that is similar to the heart-lung bypass machine used in adults. In children it has been used as a rescue therapy in the early phase of ARDS.27,28 This therapy is used most often with patients with life-threatening ARDS who have failed other therapies designed to improve oxygenation. Most of the clinical trials involving pediatric ARDS exclude patients if they have been on conventional ventilation for more than 7 days.27,28 ECMO has been successfully used in the treatment of infant respiratory distress syndrome for postterm infants diagnosed with PPHN, and the condition is considered reversible. According to Philip Wolfson, the ECMO machine is a modified heart-lung machine that provides for gas exchange in a patient suffering from hypoxemic respiratory failure.27 ECMO has been used successfully since 1974, treating more than 17,000 infants, with a survival rate of 78%.18,27,28 During the last few decades,

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Heparin

Fluids

29

Oxygen tank

Membrane lung Pump Bridge

Heat exchanger

Blood return Blood drainage

Figure 1-8 ECMO diagram

with the introduction of surfactant replacement therapy, inhaled nitric oxide, and better conventional ventilators, ECMO has been reserved for the most severe cases of infants with refractory hypoxemia. ECMO criteria have been standardized in most ECMO centers. Avery et al. suggest that most ECMO centers base their decisions on one or more of the following established criteria:28

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Table 1-4 Inclusion Criteria for ECMO ECMO Inclusion Criteria

ECMO Oxygenation Criteria

Gestational age ≥ 34 weeks or birth weight ≥ 2000 grams No significant history of bleeding No major intracranial hemorrhage Mechanical ventilation provided less than 14 days Reversible lung disease No major cardiac lesion

AaDO2 605–620 torr for 4–12 hours Oxygen index 35–60 for 0.5–6 hours PaO2 35–50 torr for 2–12 hours pH less than 7.25 for 2 hours with hypotension Acute deterioration PaO2 30–40 torr

Heliox Administration The literature has demonstrated that heliox has shown improvement in oxygenation when used in combination with HFOV for patients with ARDS.29 Helium is well understood in the treatment of asthma, RSV bronchiolitis, stridor, and other conditions affecting the upper airway.29 The benefit of helium is due to its low density and the ability to penetrate the narrowed airways. Heliox is commercially available in three mixtures: 70–30, 80–20, and 60–40. The difference between the three mixtures is the density. For example, the density of the 80–20 is 1.178, compared to 60–40, which is 0.678. Heliox has the unique ability to turn turbulent flow into laminar flow; however, in ALI/ARDS, airflow dynamic is less of an issue compared to lung compliance. Current literature supports the use of heliox in combination with other therapies; this is especially true in the treatment of asthma. There is not much research on the use of heliox as a stand-alone therapy in the treatment of ALI/ARDS. Figures 1-9 and 1-10 will illustrate heliox setup with a nebulizer and with a mechanical ventilator. Partial Liquid Ventilation There are several articles that discuss how partial liquid ventilation is used in patients on mechanical ventilation, and the concept seems simple enough, but further review shows that this therapy has not been used often in pediatric patients with ARDS in recent years. Partial liquid ventilation (PLV) is a process that takes the normal lung functional residual capacity and replaces it with perfluorocarbon liquid.30,31 Perfluorocarbon

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Figure 1-9 Heliox given with nebulizer

has the ability to dissolve large volumes of oxygen and CO2 at atmospheric pressure with the ability to reduce surface tension in lungs that are surfactant deficient.30 The major hurdle of perfluorocarbon is the ability to deliver the liquid to the airway. In this instance, a special ventilation device is needed to move the liquid tidal volume. Thus a modified technique was developed in which you fill the lungs with perfluorocarbon liquid to the functional residual capacity while the remaining gas comes from the conventional ventilator. Much of the research in animal models demonstrated an improvement in oxygenation and carbon dioxide elimination. Leach and her colleagues report that perfluorocarbon worked well in their study because perfluorocarbon was able to reduce surface tension in a diseased lung.30,31 Leach et al. reported similar findings in

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Conventional ventilator

Heliox regulator Heliox tank Air highpressure hose

Oxygen high-pressure hose Figure 1-10 Heliox in line with mechanical ventilator

their studies with premature infants with respiratory distress syndrome. They showed that within 1 hour after the administration of perflubron (market name for perfluorocarbon), gas exchange improved in the 10 infants in their study.31 The Cochrane Collaboration conducted a search of the literature on this subject from 1966 to 2003 and found one clinical trial with 182 patients enrolled in the study. This clinical trial was reportedly stopped prematurely and thus was unable to provide convincing results in support of partial liquid ventilation.32 The Cochrane authors suggest that more robust clinical trials are needed to support the efficacy of partial liquid ventilation in patients with ARDS. Summary

This chapter provided a reasonable overview of ALI/ARDS regarding the following:

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✔✔ What it is—a severe lung injury that can occur because of a number of causes and which results in poor oxygenation despite the high use of oxygen therapy ✔✔ How it presents—some research condenses it into three phases, although Whitaker divides it into four phases: • Phase 1: dyspneic, tachypneic, normal oxygenation, normal chest x-ray • Phase 2: bilateral infiltrates appear on chest x-ray • Phase 3: alveolar-capillary membrane becomes fluid filled in the distal airways and the alveoli, worsening respiratory distress, diffuse infiltrates appear on chest x-ray • Phase 4: progressive respiratory failure, lungs become fibrotic, recurrent and resistant pneumonias6 ✔✔ The importance of PEEP in the treatment of ALI/ARDS ✔✔ How it differs from other conditions like congestive heart failure ✔✔ What the research says about ALI/ARDS ✔✔ And finally, what the available supportive treatment options are ALI/ARDS is a very complex syndrome that has been well researched, yet its cure is still elusive. Continued research on ALI/ARDS holds promise that one day a cure to this most devastating condition will be available. This author suggests that although research to find a cure is ongoing, the area of supportive care has made significant strides, and as such, respiratory therapists have a number of treatment options that can be recommended for the treatment of ALI/ARDS. This is of particular importance when recommending appropriate modes of ventilation. References 1. Scanlan, C., Spearman, C., & Sheldon R. (2003). Egan’s fundamentals of respiratory care. St. Louis, MO: Mosby-Yearbook. 2. Pilbeam, S., & Cairo, J. M. (2006). Mechanical ventilation (4th ed.). St. Louis, MO: Mosby Elsevier. 3. American Lung Association. (2006, November). Fact sheet: Diseases A-Z. Adult (acute) respiratory distress syndrome (ARDS). Retrieved March 20, 2008, from http://www.lungusa.org/site/apps/nlnet/content3 4. Khemani, R.G., Patel, N. R., Bart, R. D., & Newth, C. J. (2008, November). Comparison of the pulse oximetric saturation/ fraction of inspired oxygen ratio and the Pa02/fraction of inspired oxygen ratio in children. Chest. Published online DOI: 10.1378/chest.08–2239. 5. Rubenfeld, G., Caldwell, E., Peabody, E., Weaver, J., Martin, D., Neff, M., et al. (2005, October 20). Incidence and outcomes of acute lung injury. New England Journal of Medicine, 353 (16), 1685–1693.

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6. Whitaker, K. (2001). Comprehensive perinatal and pediatric respiratory Care (3rd ed.). Albany, NY: Delmar Thomson. 7. Brower, R., Matthay, M., Morris, A., Schoenfeld, D., Thompson, T., & Wheerler, A. (2000). Ventilation with lower tidal volumes as compared with traditional tidal volumes for acute lung injury and the acute respiratory distress syndrome. New England Journal of Medicine, 342 (18), 1301–1308. Retrieved March 10, 2008, from http://content.nejm.org/cgi/ content/full/342/18/1301 8. Malhotra, A. (2007). Low-tidal volume ventilation in the acute respiratory distress syndrome. New England Journal of Medicine, 357, 1113–1120. Retrieved May 25, 2008, from http://nejm.org 9. Bernard, G. (2005). Acute respiratory distress syndrome: A historical perspective. American Journal of Respiratory and Critical Care Medicine, 172, 798–806. 10. Miles, W., & Hylton, J. (2005, August). The challenges of high frequency oscillatory ventilation. RT For Decision Makers in Respiratory Care. Retrieved March 21, 2008, from http://www.rtmagazine.com/issues/articles/2005–08_03.asp 11. The National Heart, Lung, and Blood Institute ARDS Clinical Trials Network. (2004). Higher versus lower positive endexpiratory pressures in patients with the acute respiratory distress syndrome. New England Journal of Medicine, 351, 327–336. Retrieved March 21, 2008, from http://content.nejm.org/cgi/content/full/351/4/327 12. Hanson, J. H., & Flori, H. (2006). Application of the acute respiratory distress syndrome network low-tidal volume strategy to pediatric acute lung injury. Respiratory Care Clinical North America, 12 (3), 349–357. 13. Meade, M., Cook, D., Guyatt, G., Slutsky, A., Arabi, Y., Cooper, et al. for the Lung Open Ventilation Study Investigators. (2008, February). Ventilation strategy using low tidal volumes, recruitment maneuvers, and high positive end-expiratory pressure for acute lung injury and acute respiratory distress. Journal of American Medical Association, 299 (6), 637–645. 14. Moller, J. C., Schaible, T., Roll, C., Schiffmann, J., Bindl, L., Schrod, L., et al. with the Surfactant ARDS Study Group. (2003). Treatment with bovine surfactant in severe acute respiratory distress syndrome in children: a randomized multicenter study. Intensive Care Medicine, 29, 437–446. 15. Relvas, M. S., Silver, P. C., & Sagy, M. (2003). Prone positioning of pediatric patients with ARDS results in improvement in oxygenation if maintained > 12 h daily. Chest, 124, 269–274. Retrieved January 2, 2009, from http://www.chestjournal. org/cgi/content/abstract/124/1/269 16. Baldauf, M., Silver, P., & Sagy, M. (2001). Evaluating the validity of responsiveness to inhaled nitric oxide in pediatric patients with ARDS: An analytic tool. Chest, 119, 1166–1172. Retrieved January 2, 2009, from http://www. Chestjournal. org/cgi/content/full/119/4/1166 17. MacIntyre, N., & Branson, R. (2001). Mechanical ventilation. Philadelphia: Saunders. 18. Priestly, M. & Helfaer, M. (2004). Approaches in the management of acute respiratory failure in children. Current Opinion Pediatric, 16, 293–298. 19. Higginson, R. (n.d.). High frequency oscillatory ventilation. The Internet Journal of Emergency and Intensive Care Medicine. Retrieved March 10, 2008, from http://www.ispub.com/ostia/index.php?xmlFilePath=journals/ijeicm/vol6n2/ hfov.xml 20. Griffiths, M., & Evans, T. (2005). Inhaled nitric oxide therapy in adults. New England Journal of Medicine, 353, 2683–2695. Retrieved March 23, 2008 from http://content.nejm.org/cgi/content/full/353/25/2683 21. Schreiber, M., Gin-Mestan, K., Marks, J., Huo, D., Lee, G., & Srisuparp, P. (2003). Inhaled nitric oxide in premature infants with the respiratory distress syndrome. New England Journal of Medicine, 349, 2099–2107. Retrieved March 23, 2008, from http://content.nejm.org/cgi/content/full/349/22/2099 22. Platt, D., Swanton, D., & Blackney, D. (2003). Inhaled nitric oxide (iNO) delivery with high-frequency jet ventilation (HFJV). Journal of Perinatology, 23, 387–391.

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23. Laux, L., McGonigal, M., Thieret, T., & Weatherby, L. (2008). Use of prone positioning in a patient with acute respiratory distress syndrome: A case review. Critical Care Nursing Quarterly, 31(2), 178–183. 24. Davis, J., Lemaster, D., Moore, E., Eghbalieh, B., Bilello, J., Townsend, R., et al. (2007). Prone ventilation in trauma or surgical patients with acute lung injury and adult respiratory distress syndrome: Is it beneficial? Journal of Trauma Injury, Infection and Critical Care, 62 (5), 1201–1206. 25. Alsaghir, A., & Martin, C. (2008). Effect of prone positioning in patients with acute respiratory distress syndrome: A meta-analysis. Critical Care Medicine, 36 (2), 603–609. 26. Langer, M., Mascheroni, D., Marcolin, R., & Gattinoni, L. (1988). The prone position in ARDS patients: A clinical study. Chest, 94, 103–107. Retrieved March 23, 2008, from http://www.chestjournal.org/cgi/content/abstract/94/1/103 27. Wolfson, P. J. (2003). The development and use of extracorporeal membrane oxygenation in neonates. The Annals of Thoracic Surgery, 76, 2224–2229. 28. Avery, G., Fletcher, M., & Macdonald, M. (1994). Neonatology pathophysiology and management of the newborn (4th ed.). Philadelphia: Lippincott. 29. Gupta, V., Grayck, E., & Cheifetz, I. (2004, September). Heliox administration during high-frequency jet ventilation augments carbon dioxide clearance. Respiratory Care, 49 (9), 1038–1044. 30. Leach, C., Fuhrman, B., Morin, F., & Rath, M. (1993). Perfluorocarbon-associated gas exchange (partial liquid ventilation) in respiratory distress syndrome: A prospective, randomized controlled study. Critical Care Medicine, 21, 1270–1278. 31. Leach, C., Greenspan, J., Rubenstein, D., Shaffer, T., Wolfson, M., Jackson, et al. (1996). Partial liquid ventilation with perflubron in premature infants with severe respiratory distress syndrome. New England Journal of Medicine, 335 (11), 761–767. 32. Davies M. W., & Sargent, P. H. (2004). Partial liquid ventilation for the prevention of mortality and morbidity in paediatric acute lung injury and acute respiratory distress syndrome. Cochrane Database of Systematic Reviews, 4 (CD003845), DOI: 10.1002/14651858.

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Chapter

2

Infant Respiratory Distress Syndrome (IRDS) Jacqueline Haymon Smith, BS, RRT-NPS

Chapter Outline DEFINE Prematurity • Define infant respiratory distress syndrome (IRDS) Postmaturity • Define transient tachypnea of the newborn (TTN) • Define meconium aspiration syndrome (MAS) • Define congenital diaphragmatic hernia (CDH) • Define persistent pulmonary hypertension of the newborn (PPHN) • Define surfactant replacement therapy (SRT) DESCRIBE • Describe the clinical presentation of IRDS • Describe the etiology of IRDS • Discuss whom IRDS affects • Describe the benefit of surfactant replacement therapy in preterm infants DISTINGUISH • Neonatal pneumonia with group B streptococcus (GBS) • Neuromuscular disease • Mechanical restrictive problems

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RESEARCH • Relevant research on IRDS • Relevant research on surfactant replacement therapy (SRT) TREATMENT • Treatment options in the care of IRDS patients • Respiratory therapist role in the management of IRDS

Key Terms Acute lung injury Acute respiratory distress syndrome Extracorporeal membrane oxygenation (ECMO) High-frequency oscillatory ventilation (HFOV) Infant respiratory distress syndrome Inhaled nitric oxide Lung protective strategy Mechanical ventilator

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Chapter 2 Infant Respiratory Distress Syndrome (IRDS)

INTRODUCTION

When first asked by the author to write a chapter in this book, I was elated; it was the highest compliment that anyone could afford me. I thought, finally I can put to paper my various experiences as a neonatal pediatric specialist in respiratory care. I can recall some hair-raising stories that really challenged me and brought every bit of my respiratory knowledge, experience, and education into play. I could not wait to have a venue to share these experiences, and hopefully help other healthcare professionals avoid some of the pitfalls and embarrassing moments that, through trial and error, I have had to endure. As an experienced respiratory therapist in a neonatal intensive care unit, I have seen the hope and hopelessness of many parents who were told that their child had one of the manifestations of infant respiratory distress syndrome (IRDS). The prognosis for these infants can be dismal and depends on so many influences before, during, and after the delivery. There is always hope, and as the compassionate clinician, you find yourself hoping right along with the parents. Although modern medicine has improved the mortality and morbidity of these children, there are many treatment procedural possibilities that you, the bedside clinician, might recommend. These treatment options can bring about a positive change. This chapter will focus on the most prominent life-threatening entities that result in IRDS: prematurity of the newborn, transient tachypnea of the newborn (TTN), congenital diaphragmatic hernia (CDH), meconium aspiration syndrome (MAS), and persistent pulmonary hypertension of the newborn (PPHN). Research has shown that preterm and term infants are more likely to suffer from any one of these conditions soon after birth. The key to successful management for these babies is early recognition and early action. DEFINE

By definition, the word syndrome means a certain set of established signs and symptoms occurring concurrently to indicate a disease process to an organ or system. The National Institutes of Health and the U.S. National Library of Medicine define infant respiratory distress syndrome

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(IRDS) as a complication that can make it difficult for the premature infant to breathe.1,2,3 Infant respiratory distress syndrome that is called hyaline membrane disease (HMD) or respiratory distress syndrome (RDS) is a condition that affects the terminal bronchioles and alveolar ducts in which the hyaline membrane is a fibrinous material composed of blood and cellular debris.3 The lining of the lungs are ruddy in appearance and airless, and the main feature of this condition is widespread diffuse atelectasis.3 IRDS is caused by the absence of proper surfactant production due to an immature or poorly developed lung, such as that seen in the premature infant.4,5 In the postmature lungs, IRDS is the result of disruption of airflow with subsequent atelectasis causing an acute lung injury.3 Other causes of IRDS can be categorized as genetic deficiencies that affect lung development, lung structural defects, diaphragmatic abnormalities, phrenic nerve abnormalities, and/or rib cage defects. The main cause of IRDS is a lack of surfactant, which prohibits the lungs from expanding and recoiling. The inability of the lungs to expand creates a ventilation perfusion mismatch or shunt, which leads to poor oxygenation of the blood, or hypoxemia. The lack of perfusion to the poorly developed lungs prevents circulation of oxygen to vital organs. Although IRDS is seen predominantly in the premature infant, the respiratory therapist is often asked to see infants who display signs and symptoms of respiratory distress several hours after birth. Consider the following conditions. Transient tachypnea of the newborn is the increase in respiratory rate, greater than 60, of a newly born infant. Historically, it was believed that TTN happened most often in babies born through cesarean section, but this belief is still controversial. Avery et al. conclude that TTN is the delayed reabsorption of lung fluid at the time of birth.6 It is believed that TTN is the result of an immature surfactant system, which showed a lack of phosphatidylglycerol in amniotic fluid.6 Risk factors include prematurity, maternal sedation, maternal bronchodilator therapy for asthma during pregnancy, maternal increase in fluids during pregnancy, and fetal asphyxia. Meconium aspiration syndrome occurs when the fetus passes fecal material that has accumulated during gestation (usually due to fetal stress) into the amniotic fluid and the fecal material is aspirated into

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the fetus’s lungs. Interestingly, the term meconium comes from the Greek word mekoni, meaning poppy juice or opium. Meconium-stained infants admitted to the nursery tend to reflect an infant who is under the influence of the same drugs that the mother has received. The word mekoni refers to the subdued response shown by these infants, similar to how one would act under the influence of opium.7 Meconium is a viscous green liquid material composed of gastrointestinal secretions, cellular debris, bile and pancreatic juice, mucus, blood, lanugo, and vernix.6 Meconium aspiration contributes to fetal asphyxiation and very low venous PaO2 prior to birth of the infant. Fetal asphyxiation occurs as a result of the infant’s gasping respiratory efforts that allow meconium into the respiratory tract. Meconium that is detected below the vocal cords is indicative of meconium aspiration syndrome. Congenital diaphragmatic hernia is a hole in the wall of the diaphragm that permits abdominal content to migrate into the chest cavity. This migration results in poorly developed lungs, a heart that has shifted, and profound cyanosis and respiratory distress at birth.3 Persistent pulmonary hypertension of the newborn, formally known as persistent fetal circulation (PFC), is the persistent elevation of pulmonary vascular pressure in a newborn in the absence of any other recognizable conditions. Avery and colleagues refer to this condition as the “failure to make the transition from high pulmonary vascular resistance (PVR) and low pulmonary blood flow, characteristic of the fetus, to the relatively low PVR and high pulmonary blood flow of the postnatal infant.”6 Clinical Note A newborn’s grunt, the sound produced when breathing against a closed glottis, is the equivalent of the amazing concept of PEEP (positive end-expiratory pressure). Observation reveals that at the end of each inspiration, an infant grunts. The infant will actually hold his or her breath for a second, bear down, and grunt just before exhalation. The infant may be observed using accessory muscles, tachypneic, and nasal flaring. This simple maneuver builds pressure in the lungs, forcing oxygen across the alveolar capillary membrane. It also helps to maintain patency of the alveolar sacs. Although grunting is somewhat effective at keeping the patient’s oxygen level up, the infant’s work of breathing is also increased, which makes it less likely that the infant is able to continue this effort for very long.

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Depending on the effort the infant is exerting, the respiratory therapist may be asked to provide supplemental oxygen and/or pressure to the patient who is grunting to relieve some of the work of breathing. This can be provided via nasal CPAP or the more recent and friendlier method of a high humidity nasal cannula. The infant is watched carefully for signs of tiring. At the first sign of the infant becoming tired, usually a decrease in oxygen saturation as displayed on a pulse oximeter, it may become necessary to utilize additional interventions. It is extremely important for the clinician to keep a careful eye on this type of patient. There should be frequent monitoring of the respiratory rate and the patient’s oxygen saturation. If the patient deteriorates, intervention has to happen quickly. DESCRIBE

Infant respiratory distress syndrome, or hyaline membrane disease (HMD), is described in low or extremely low birth-weight babies who present with respiratory distress within the first minutes to hours following birth. This condition manifests itself when there is a lack of surfactant production in the lungs. The infant’s lungs become lined with damaged lung cells and protein, which leaks into the alveoli-capillary bed, causing the alveoli to be lined with hyaline cartilage. Hyaline membranes form in response to the damaged lung.3,4,5,6,8 These membranes make it difficult for the lung to expand and, more important, for oxygen to cross the alveolar capillary membrane into the bloodstream, which prevents vital organs from being oxygenated. The following are some of the symptoms of infants with respiratory distress: • • • • • • • • • •

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Cyanosis Apnea Decreased urine output Nasal flaring Puffy or swollen arms or legs Rapid breathing Shallow breathing Shortness of breath and grunting sounds while breathing Paradoxical chest wall movement with breathing Increased oxygen requirement

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Breath sounds that include rales Poor lung aeration Accessory muscle usage Chest x-ray showing atelectasis, air bronchograms, and granular infiltrates

The clinical course of an infant with respiratory distress syndrome depends on the size and maturity of the infant. The more profound clinical symptoms appear in the extremely low birthweight and early gestational age babies: those who weigh less than 1000 grams and are born at gestational age of less than 25 weeks. Transient tachypnea of the newborn is described as a sudden increase in respiratory rate shortly after birth that usually continues for 2 to 5 days. Symptoms of TTN include grunting and retractions. This condition is self-limiting and usually subsides within a few days. If the infant displays moderate to severe symptoms of distress, consideration must be given to maintaining adequate oxygenation and ventilation. Meconium aspiration syndrome occurs in about 10%–15% of all births.8 The infant’s skin may be stained with the yellowish-green meconium, his or her nail beds may have the meconium caked under them and be blue, and often you can visualize meconium in the oropharynx. The infant’s respiratory efforts are directed toward getting oxygen to the lungs and tissue. Aspiration of meconium causes a mechanical obstruction in the lungs, further preventing effective oxygenation. Avery et al. indicated that MAS produces decreased lung tissue compliance and parenchymal lung damage.6 Additionally, MAS produce a ball-valve mechanism that partially closes the airway and contributes significantly to air trapping, increased expiratory lung resistance, and increased functional residual capacities.6,7 In complete closure of the airway, the result of widespread atelectasis and significant perfusion ventilation mismatch will occur. In babies with severe MAS, this leads to pulmonary hypertension with right-to-left shunting.6,7 The following are typical signs of MAS: • Tachypneic • Nasal flaring

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• Retractions • Cyanosis Congenital diaphragmatic hernia usually involves profound cyanosis with severe respiratory distress at birth. There is urgency in this infant to reverse the hypoxia, hypercarbia, and metabolic acidosis that is evident at birth.3,6 Historically, this was an operative condition that required immediate surgery; however, this condition now requires aggressive presurgery treatment to manage oxygenation and ventilation to avoid the devastation associated with persistent pulmonary hypertension of the newborn. Poor oxygenation is secondary to poorly oxygenated blood being shunted through the foramen ovale and the ductus arteriosus causing a right-to-left shunt. Failure to reverse these sequences of events could result in the infant’s death. Persistent pulmonary hypertension of the newborn is the delay of the fetal circulation to transition from the prebirth systemic circulation to the postbirth systemic circulation. Avery et al. describes the transition in four phases: • In utero phase—immediate phase that occurs in the first minutes after birth and is characterized as PVR that exceeds systemic vascular resistance. In utero blood bypasses the lung. • Immediate phase—fluid-filled fetal lungs are distended with the first breath. PVR is decreased with the rapid entry of air into the alveoli. • Fast phase—accounts for the greatest reduction in PVR, which occurs 12 to 24 hours after birth. A drop in PVR has been associated with an increase in the production of prostacyclin and nitric oxide, which are vasodilators. • Final phase—results in the remodeling of the pulmonary vascular musculature. In a normal fetal and term lung, fully muscularized, thick-walled preacinar arteries extend to the level of the terminal bronchioles. Hypoxia at birth prevents this remodeling of smooth muscle.6 PPHN usually affects full-term babies who are born with a continuation of hypoxemia despite the lack of significant lung disease. Typical signs of respiratory distress are indistinguishable from many other conditions

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that affect infants; however, a careful maternal history often reveals signs of perinatal asphyxia. PPHN must be distinguished so that appropriate treatment is implemented. Causes of PPHN, such as MAS, IRDS, and congenital diaphragmatic hernia, are discussed elsewhere in this chapter. NICU Respiratory Therapist Factoids I recall an extremely busy shift, and at the end of my shift I did not have time to replace the equipment I had used during the shift. I relayed this situation in report, and the oncoming therapist was appalled. I was reminded that failure to replace equipment used was unacceptable. This seemingly innocent oversight could cost time and energy to find and set up equipment, which ultimately would hinder the ability to provide the necessary clinical expertise that would be needed at that very moment. At first glance, I was offended; however, as I thought more about the situation, I realized that the oncoming respiratory therapist was right. NICU and pediatric intensive care units (PICU) tend to be fast paced, and because of time limitations, the urgency with which the patient needs intervention, there is an expectation that different types of equipment be set up and ready to go. Nowhere is this more important than in a NICU or PICU. If this means that the person on the off-going shift needs to stay a little longer to set things up and restock supplies, then so be it. When called upon to set up equipment to manage a very unstable patient with PPHN, there are no moments for hesitation. In the future, you and your colleagues will learn to appreciate this more than you will ever know. In reality, this is just a level of respect and professionalism that every clinician should have.

DISTINGUISH

There are several conditions that mimic IRDS at birth. The three most common conditions are neonatal pneumonia with group B streptococcus (GBS), neuromuscular diseases, and mechanical restrictive disorders. There are many more conditions that would easily fit into this category; however, this chapter will highlight the above mentioned, because they are more likely to be seen in a NICU or PICU setting. Neonatal pneumonia with group B streptococcus (GBS) occurs quite often in the neonate. It can be acquired transplacentally, during the birth process, or postnally.6 GBS is the most common bacteria that affect neonate in the first week of life, occurring from 1.3 to 3 per 1000 live births.6 GBS is found in the genital and intestinal flora of pregnant women, and the bacteria are easily able to pass from mother to baby. A chest x-ray is

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Table 2-1 At-a-Glance Conditions that Affect Premature and Postmature Infants with RDS Disease

Common Symptoms

Chest X-Ray

Respiratory distress syndrome or hyaline membrane disease

Cyanosis, apnea, nasal flaring, grunting, rapid shallow breathing pattern, accessory muscle usage

Atelectasis, air bronchograms, granular infiltrates

Transient tachypnea of the newborn

A sudden increase in respiratory rate; occurs shortly after birth and continues for 2 to 5 days; grunting and retractions

Hyperexpansion of the lungs perihilar and interstitial streaky infiltrates flattening of the diaphragm, mild to moderate enlarged heart and increased pulmonary vascular markings

Meconium aspiration syndrome

Tachypneic, nasal flaring, retractions, and cyanosis

Bilateral, patchy, coarse infiltrates, hyperinflation of the lung

Congenital diaphragmatic hernia

Profound cyanosis at birth, flat stomach

Bowel gas pattern in one hemithorax with a shift of mediastinal structures to the other side and compromise of the opposite lung

Persistent pulmonary hypertension of the newborn

Profound cyanosis, severe ventilation, and perfusion mismatch, insignificant lung disease

Cardiomegaly or normal size heart; if there is no associate pulmonary disease, chest x-ray may show normal or diminished pulmonary vascularity; if there is lung disease, hypoxemia may be disproportion to the radiographic measure of pulmonary disease severity

Data from: Gomella, T. L. (2004). Neonatology: Management, procedures, on-call problems, diseases, and drugs (5th ed., pp. 110–111, 366, 547, and 578). New York: McGraw-Hill.

helpful in distinguishing GBS from infant respiratory distress syndrome. It may show pleural effusion, increased vascular markings, or patchy infiltrates.6 Werdnig-Hoffman disease, also known as infantile spinal muscular atrophy type I, is a degenerative neuromuscular disease of the spinal motor plate (see Chapter 10 for a full discussion). Often this is detected in utero: the mother notices that there has been a cessation of movement in an otherwise active fetus. At birth, the infant will show signs of

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respiratory distress with profound weakness, retractions, and abdominal distention.3 Myasthenia gravis can occur in newborn, although it is thought to be rare. Faranoff and Martin discuss two forms: (1) neonatal myasthenia gravis, which occurs only in mothers with myasthenia gravis, and (2) congenital myasthenia gravis, which occurs in mothers without a history of myasthenia gravis. In both forms of myasthenia gravis, the infant displays respiratory difficulty immediately after birth, with signs of generalized weakness, feeble cry, poor sucking, facial weakness, and ptosis.3 Maternal history is the key to distinguishing this form of infant respiratory distress. There are a number of neonatal upper airway obstructions that often present immediately after birth and cause significant respiratory distress. Of these mechanical restrictive problems, choanal atresia, Pierre Robin syndrome, and tracheoesophageal fistula are the more common airway obstructions observed in the NICU. Choanal atresia is a malformation of the nasopharynx area. Newborns are considered obligate nose breathers and must learn to breathe through their mouth immediately. Signs of cyanosis are present at birth. Establishment of an airway is required followed by corrective surgery. Pierre Robin syndrome is a combination of undersized jaw, cleft of the soft palate, and a tongue that falls toward the back of the throat, causing airway obstruction. Infants with this condition have respiratory difficulty, with cyanosis, poor feeding, and failure to thrive. Tracheoesophageal fistula is a communication between the stomach and the esophagus that may lead to aspiration pneumonia. Children with this condition produce copious amounts of secretions that lead to choking. Careful monitoring of these infants is necessary because in severe circumstances respiratory distress may progress to respiratory failure. RESEARCH

Advances in medical management of infant respiratory distress syndrome have changed the natural course of this condition. Improvement in antenatal corticosteroid administration to mothers at risk for premature delivery, surfactant replacement therapy, and much more sophisticated

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conventional ventilator used in the delivery room play a role in reducing the incidence of IRDS. Geoffrey Argons et al. reported in 2002 that the number of infants born before 37 weeks’ gestation in the United States was 487,000, which represented 12.1% of all live births and a 14% increase from 1990.9 Their report attributes this rise in preterm birth to the increase number of multiple births secondary to fertility therapy. Medical management of the preterm infant has improved significantly, resulting in the management of preterm infants as young as 23–24 weeks’ gestational age. Historically, infants this young would not survive extrauterine life, due to their pulmonary immaturity, which leads to severe tissue damage and poor gas exchange. The introduction of surfactant replacement therapy has dramatically improved the mortality of these infants and subsequently has lowered morbidity. Instillation of surfactant in the preterm infant before the first breath has been shown to decrease the incidence of respiratory distress syndrome. There are a number of surfactant preparations that have been approved by the U.S. Food and Drug Administration, including the synthetic preparations Exosurf, Survanta, and Infasurf, and the natural surfactant Curosurf. Both synthetic and natural surfactants have been shown to improve the incidence of respiratory distress syndrome by lessening the need for aggressive mechanical ventilation, less frequent pneumothorax, and decreased mortality.4,5,9 The use of continuous positive airway pressure (CPAP) has been shown to improve oxygenation and ventilation of the preterm infant while minimizing ventilator associated lung injuries.10,11 Although many preterm infants will need continuous ventilator support, some studies show that the use of high-frequency oscillatory ventilation (HFOV) has shown some success in optimizing gas exchange in these preterm babies.12,13,14 Infants under 34 weeks’ gestational age in most neonatal centers are not candidates for extracorporeal membrane oxygenation (ECMO) secondary to intracranial hemorrhage. ECMO is reserved for children weighing more than 2000 grams and older than 34 weeks’ gestational age.3 High-frequency jet ventilation (HFJV) is another type of high-frequency ventilation that is very different than HFOV in that it delivers gases from a high-pressure source through a small bore cannula.15,16 It delivers rates from 150 to 600 and has demonstrated well in

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CO2 elimination. It has become a standard in treating IRDS patients with pulmonary interstitial emphysema (PIE). TREATMENT

Treatment of IRDS is still controversial, but listed below are several methods that are shown to be beneficial: • • • • • •

Surfactant replacement therapy (SRT) Continuous positive airway pressure (CPAP) High-frequency oscillatory ventilation (HFOV) High-frequency jet ventilation (HFJV) Administration of inhaled nitric oxide (iNO) Extracorporeal membrane oxygenation (ECMO)

Surfactant replacement therapy is the first line of defense in the treatment of IRDS. The amount of surfactant is determined by the patient’s weight; it is then warmed to body temperature and prepared for administration to the lungs via an endotracheal tube. The patient is intubated with an appropriate size endotracheal tube. Surfactant is delivered down either the endotracheal tube or through a side port attached to the endotracheal tube. The patient is manually resuscitated for several positive pressure breaths to get the surfactant to the periphery of the lung, or the patient is placed on the ventilator to provide positive pressure breaths; the latter is preferable because it provides consistent positive pressure breaths. The ventilator pressure is closely monitored so that it does not further damage the lungs. The respiratory therapist typically stays at the bedside to monitor the pressure being delivered by the ventilator. As lung compliance improves, the pressure is decreased in small increments, usually between 2 and 5 centimeters of water pressure. Some infant ventilators can now indicate compliance changes by monitoring volume changes. Care should be taken to not decrease the pressure too quickly. Once the optimal pressure is determined, the infant may be maintained on the ventilator; in some instances, the infant is extubated after a predetermined time and is transitioned to nasal CPAP. Nasal CPAP is pressure, flow, and oxygen delivered continuously to the airway to maintain expansion of the alveoli and promote oxygen.

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It can be delivered via a mechanical ventilator, the Infant Flow device made by Viasys Healthcare, or a heated, high-humidity nasal cannula (HHHNC; see Figure 2-1). High-humidity nasal cannula has been gaining ground in many nurseries as the alternative to mechanical ventilation. Some studies have shown that it is not comparable to the traditional CPAP and does not generate any increase in pressure for the infant while the infant’s mouth is opened;11 however, any device that delivers pressure to an infant with its mouth open will be inadequate. Additionally, the use of Vapotherm (see Figure 2-2) has also seen increased use in NICU. Other studies show that there is little to no difference in overall mortality between a group of infants with gestational age of 25 to 28 weeks ran-

Figure 2-1 High heated humidity nasal cannula

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Figure 2-2 Vapotherm

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domized to CPAP or intubation and ventilation. My personal experience with HHHNC has been successful, and in most instances I was able to prevent mechanical ventilation. A word of caution: The respiratory therapist will need to closely monitor the infant and be creative to prevent pressure and/or flows from escaping through the infant’s mouth. High-frequency oscillatory ventilation uses a ventilator that operates with principles different from the conventional ventilators. A mean airway pressure (Paw) is created by delivering a bias flow past a resistance.12,14 This maneuver virtually creates CPAP, through a closed system via the endotracheal tube and the ventilator circuit, and is delivered to the lungs to help maintain lung volume. This pressure inflates the lung, minimizes the ventilation perfusion mismatch, and increases the alveolar surface area for gas exchange. This results in better oxygenation for the patient. There are lots of controversies surrounding high-frequency ventilation in the treatment of IRDS: some authors say that high-frequency ventilation is just as effective as conventional ventilation.10,17 Inhaled nitric oxide administration is a selective pulmonary vasodilator and produces increased systemic oxygenation, with minimal side effects to the patient.18 It is beneficial in treating IRDS for those infants with PPHN. There is an increase in pulmonary vascular resistance, causing blood to shunt away from the lungs. Inhaled nitric oxide helps to lower pulmonary vascular resistance by promoting pulmonary vasodilation. ECMO has been used in the treatment of IRDS when it manifests itself as PPHN and the condition is considered reversible. According to Philip Wolfson, the ECMO machine is a modified heart-lung machine that provides for gas exchange in a patient who is suffering from hypoxemic respiratory failure.19 ECMO has been used successfully since 1974, treating more than 17,000 infants, with a survival rate of 78%.19 During the last few decades with the introduction of surfactant replacement therapy, inhaled nitric oxide, and better conventional ventilators, ECMO has been reserved for the most severe cases of infants with refractory hypoxemia.

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Table 2-2 At-a-Glance Treatment Options for Patients Diagnosed with RDS Disease

Treatment Option

Respiratory distress syndrome or hyaline membrane disease

Antenatal corticosteroids, surfactant replacement therapy

Transient tachypnea of the newborn

Supplemental oxygenation, antibiotics, fluid, electrolytes, and diuretics

Meconium aspiration syndrome

Prevention of meconium during the prenatal period, intubation and suction below the vocal cords using a meconium trap aspirator, supplemental oxygen therapy, mechanical ventilation, high-frequency jet ventilation or high-frequency oscillator ventilation, or extracorporeal membrane oxygenation (ECMO)

Congenital diaphragmatic hernia

Indwelling arterial catheter, possible use of surfactant replacement therapy, nasogastric tube, surgical correction, or ECMO

Persistent pulmonary hypertension of the newborn

Prevention of the cause of PPHN, mechanical ventilation, surfactant may be helpful, vasopressor may be helpful to improve blood pressure, sedation, inhaled nitric oxide: 20 ppm to start, and ECMO

Data from: Gomella, T. L. (2004). Neonatology: Management, procedures, on-call problems, diseases, and drugs (5th ed., pp. 367–370 and 541–549). New York: McGraw-Hill.

Summary

In spite of the advances in medical management, infant respiratory distress syndrome still occurs in 20,000 to 30,000 infants born each year in the United States. The introduction of surfactant therapy and better ventilator management strategy has significantly improved the mortality and morbidity of these infants. This chapter highlighted the following: ✔✔ Infants born before 37 weeks are at increase risk of infant respiratory distress syndrome, because of lack of surfactant production. Administration of surfactant prior to the infant’s first breath has been shown to be beneficial. ✔✔ Infants displaying meconium below the vocal cord are at risk for respiratory distress secondary to meconium aspiration syndrome. Aggressive suctioning below the vocal cords is the first line of therapy. ✔✔ Infants who are postterm, 24 hours to 48 hours postbirth, and display signs of grunting and retractions with respirations greater

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✔✔

✔✔

✔✔ ✔✔

53

than 60 are diagnosed with transient tachypnea of the newborn. This condition is self-limiting and is usually supported by oxygen therapy and careful monitoring. The condition in which an infant is born with a hole in his or her diaphragm that allows abdominal content into his or her chest wall is called congenital diaphragmatic hernia. This condition requires quick action to support the child’s oxygenation needs first. Postterm infants whose pulmonary vascular pressure remains high after birth are identified as having persistent pulmonary hypertension of the newborn. Infants born with meconium aspiration, transient tachypnea of the newborn, or congenital diaphragmatic hernia are at increased risk for PPHN due to the hypoxia insult to the lung tissue. Treatment of choice for preterm infants is surfactant therapy along with gentle positive pressure ventilation. Treatment of choice for postterm infants could be as simple as gentle positive pressure ventilation, inhaled nitric oxide, or highfrequency ventilation, and/or ECMO for the very severe case of IRDS.

References 1. Neonatal respiratory distress syndrome. In: Medline Plus Medical Encyclopedia. Retrieved March 23, 2008, from http:// www.nlm.nih.gov/medlineplus/encyclopedia.html 2. Cloherty, J., Stark, A., & Eichenwald, E. (2003). Manual of neonatal care (5th ed.). Philadelphia: Lippincott, Wilkins and Williams. 3. Fanaroff, A. A., & Martin, R. J. (2002). Neonatal-perinatal medicine: Diseases of the fetus and infant (Vol. 2, 7th ed.). St. Louis, MO: Mosby. 4. Coles, F. S. (2006, October). Defects in surfactant synthesis: clinical implications. Pediatric Clinical North America, 53 (5), 911–927. 5. Stevens, T. P. (2007, May). Surfactant replacement therapy. Chest, 131(5), 1577–1582. Retrieved July 7, 2007, from http://www.chestjournal.org/cgi/content/full/131/5/1577 6. Avery, G., Fletcher, M., & Macdonald, M. (1994). Neonatology pathophysiology and management of the newborn (4th ed.). Philadelphia: Lippincott. 7. Ross, M. G. (2005). Meconium aspiration syndrome—More than intrapartum meconium. New England Journal of Medicine, 353 (9), 946–948. Retrieved March 23, 2008, from http://content.nejm.org/cgi/content/extract/353/9/946 8. Pramanik, A. K. (2006, October). Respiratory distress syndrome. eMedicine. Retrieved July 7, 2007, from http://www. emedicine.medscape.com/article/976034-overview

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9. Agrons, G. A., Courtney, S. E., Stocker, J. T., & Markowitz, R. I. (2005). Lung disease in premature neonates: Radiologicpathologic correlation. RadioGraphics, 25, 1047–1073. 10. Courtney, S. E. (2007, March). Continuous positive airway pressure and noninvasive ventilation. Clinical Perinatology, 34 (1), 73–92. 11. Ahluwalia, J. S., White, D. K., & Morley, C. J. (1998). Infant flow driver or single prong nasal continuous positive airway pressure: Short-term physiological effects. Acta Paediatrica, 87 (3), 325–327. 12. Lampland, A. L. (2007, March). The role of high-frequency ventilation in neonates: Evidence-based recommendations. Clinical Perinatology, 34 (1), 129–144. 13. Henderson-Smart, D. J., Cools, F., Bhuta, T., & Offringa, M. (2007). Elective high frequency oscillatory ventilation versus conventional ventilation for acute pulmonary dysfunction in preterm infants. Cochrane Database of Systematic Reviews, 3. Art. No.: CD000104. DOI: 10.1002/14651858.CD000104.pub2. 14. Courtney, S.E, Durand, D.J., Asselin, J.M., Hadah, M. L., Aschner, J.L., & Shoemaker, C. T. (2002). High-frequency oscillatory ventilation versus conventional mechanical ventilation for very-low-birth-weight infants. New England Journal of Medicine, 347 (9), 633–642. Retrieved July 7, 2007, from http://content.nejm.org/cgi/content/abstract/347/9/643 15. Keszler, M., Donn, S., & Bucciaerelli, R. (1991). Multicenter controlled trial comparing high-frequency jet ventilation and conventional mechanical ventilation in newborn infants with pulmonary interstitial emphysema. Journal of Pediatrics, 119, 85–93. 16. Bunnell, B. (1994, December 8). Life Pulse high-frequency jet ventilator reference manual. Salt Lake City, UT: Author. 17. Boggs, W. (2006). Ventilation mode does not influence every preterm infant outcome. Archives of Diseases in Childhood: Fetal and Neonatal Edition, 91, F315–F316, F320–F326. 18. Kinsella, J.P., & Abman, S.H. (2007). Inhaled nitric oxide in the premature newborn. Journal of Pediatrics, 151(1), 10–15. 19. Wolfson, P. J. (2003). The development and use of extracorporeal membrane oxygenation in neonates. Annals of Thoracic Surgery, 76, 2224–2229. Accessed March 23, 2008, from http://www.ats.ctsnetjournals.org/cgi/content/ full/76/6/S2224

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Asthma Chapter Outline DEFINE • Define asthma • Define severe asthma exacerbation • Discuss who is affected by asthma DESCRIBE • Describe the clinical presentation of asthma • Describe the difference between asthma and severe asthma exacerbation • Describe asthma severity according to the national guidelines DISTINGUISH • Distinguish asthma from other conditions RESEARCH • Relevant research on asthma TREATMENT • Treatment options in the care of asthmatic patients • Respiratory therapist role in the management of asthmatic patients

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Key Terms Anticholinergic Asthma Asthmaticus Arterial blood gas Artificial airway Bronchodilators Corticosteroids Endotracheal intubation Heliox Ketamine Magnesium sulfate

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Introduction

Early in my practice as a respiratory therapist, I recall working with a young boy who was diagnosed with severe asthma. Every 3 months he would come to the emergency room to be treated for his asthma symptoms. We knew this child all too well. One day he came to the emergency room with what seemed to be his routine asthma needs, but this time the asthma therapy was not working. It became obvious to me that this would be my last time to treat this child. Our team worked hard to save this child, yet in the end he slipped away. My heart lay heavy for many months trying to make sense of it all, only to be reminded of this very thing: “Asthma kills.” DEFINE

Asthma is a chronic inflammation of the airways with reversible episodes of obstruction, caused by an increased reaction of the airways to various stimuli. Asthma breathing problems usually happen in “episodes” or attacks, but the inflammation underlying asthma is continuous.1,2 Figure 3-1 depicts a normal and an abnormal airway. In a nutshell, asthma is a chronic inflammation of the airway with two distinctive components: (1) the squeezing of the muscles around the airway, followed by (2) the production of mucus that clogs the airway. The formal definition, as presented in the National Asthma Education and Prevention Program (NAEPP)’s Expert Panel Report 3 (EPR3; 2007) is as follows: Asthma is a chronic inflammatory disorder of the airways in which many cells and cellular elements play a role: in particular, mast cells, eosinophils, neutrophils (especially in sudden onset, fatal exacerbation, occupational asthma, and patients who smoke), T lymphocytes, macrophages, and epithelial cells. In susceptible individuals, this inflammation causes recurrent episodes of coughing (particularly at night or early in the morning), wheezing, breathlessness, and chest tightness. These episodes are usually associated with widespread but variable airflow obstruction that is often reversible either spontaneously or with treatment.3

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Normal Narrowed Mucus obstructing bronchiole

Figure 3-1 Normal and abnormal airway

Severe Asthma Exacerbation Although the NAEPP guidelines offer an excellent definition of asthma, patients who are admitted to the pediatric intensive care unit (PICU) with the severe form of asthma are commonly diagnosed with severe asthma exacerbation. According to Andrew Schwarz, MD, severe asthma exacerbation is a severe asthma attack that does not respond to the initial treatment with bronchodilators.4 It is characterized by persistent wheezing with retractions and can result in high carbon dioxide levels and low oxygen levels. Heinrich Weiner, MD, reports in his review that severe asthma exacerbation, “is the condition of a patient in progressive respiratory failure due to asthma, in which conventional forms of therapy have failed.”5 Whom Does Asthma Affect? Asthma is among the 10 leading chronic conditions causing restricted activity and is the most common cause of chronic illness in children.6 Asthma statistics are alarming. Data from the 2005 CDC National Health

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Interview Survey reveals the following. An estimated 7.7% of people in the United States (22.2 million) currently have asthma. The rate for children was 8.9% (6.5 million).7 The Environmental Protection Agency (EPA) notes that 17% of all households with children have at least one child diagnosed with asthma and that people from low-income, low-education households were more likely to have asthma.8 Although asthma is a pervasive problem, it does not affect all groups of children equally. Reports indicate that asthma has become a leading public health concern particularly in minority populations. Poor children are at especially high risk of hospitalization for asthma. The emergency department (ED) visit rate for African Americans was 350% higher than that for white people, and asthma hospitalization rate for African Americans was 240% higher.8 It has been recognized that African Americans are four times more likely to be hospitalized and five times more likely to die of asthma than non-African Americans.9,10 CDC’s report Healthy Youth!—Asthma cites a study that finds that children living in inner city areas experience more emergency department visits, hospitalizations, and deaths due to asthma than the general population. Similarly, these children have more missed school days and their families have a greater number of missed workdays due to asthma.10 Direct healthcare costs for asthma in the United States total more than $10 billion annually and indirect costs (lost productivity) add another $8 billion (2007).11 DESCRIBE

Clinical Presentation The hallmark of asthma is periodic recurrent of symptoms such as wheezing, shortness of breath, chest tightness, and coughing. Either internal or external triggers stimulate the hypersensitivity of the airway, causing what we know as an “asthma attack.” There are a number of changes in the airway that promote airway hyperresponsiveness: • Bronchoconstriction—smooth muscles narrow in response to either internal or external stimulus • Hypersensitivity—an exaggerated response to a stimulus • Airway edema—formation of mucus in the airway, which further limits airflow3

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Causes of Asthma Although the research is not conclusive as to the cause of asthma, there are three theories that have been discussed: • Low immunity during childhood—according to the “hygiene hypothesis,” exposure to infections early in childhood helps to build the immune system, which then becomes a defense mechanism against childhood illnesses. It is believed that children who were not exposed to diseases early in life may have increased risk of developing asthma or asthma-like symptoms. • Genetics—there is ongoing research to determine the link between genetics and asthma. There is a notion that asthma is passed along in families from one generation to the next. • Exposure to house dust mites and viral respiratory infections—the NAEPP has identified exposure to dust mites and viruses as the two most important environmental factors in the development of asthma.3

Table 3-1 Asthma Triggers External Triggers

Internal Triggers

Tobacco smoke

Viral infection

Dust mites

Stress

Animal dander

Strong emotional expression

Cockroach

Menstrual cycles

Vacuum cleaning

Exercise

Indoor mold Pollen and outdoor mold Smoke strong odors and spray Sulfites in food Cold air Other medicines Source: National Asthma Education and Prevention Program Expert Panel Report 3, Guidelines for the Diagnosis and Management of Asthma. US Department of Health and Human Services, National Institutes of Health, National Heart, Lung, and Blood Institute, NIH Publication Number 08-5846, October, 2007

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The Difference Between Asthma and Severe Asthma Exacerbation Tables 3-2 and 3-3 describe signs and symptoms of both asthma and severe asthma exacerbation. Table 3-2 NAEPP Classification of Signs and Symptoms of Asthma Medical History Cough (worse particularly at night) • Recurrent wheeze • Recurrent difficulty in breathing • Recurrent chest tightness Aggravating Factors • Exercise • Viral infection • Inhalant allergens (e.g., animals with fur or hair, house dust mites, mold, pollen) • Irritants (tobacco or wood smoke, airborne chemicals) • Changes in weather • Strong emotional expression (laughing or crying hard) • Stress • Menstrual cycles Symptoms occur or worsen at night, awakening the patient. Note: The presence of multiple key indicators increases the probability of asthma, but spirometry is needed to establish a diagnosis. Wheezing is a high-pitched whistling sound that is noticeable when breathing out, especially in children. A lack of wheezing and a normal chest examination do not exclude asthma. Source: National Asthma Education and Prevention Program Expert Panel Report 3, Guidelines for the Diagnosis and Management of Asthma. US Department of Health and Human Services, National Institutes of Health, National Heart, Lung, and Blood Institute, NIH Publication Number 08-5846, October, 2007

Table 3-3 NAEPP Classification of Severe Asthma • • • • • • • •

Previous severe exacerbation (e.g., intubation or ICU admission for asthma) Two or more hospitalizations or greater than three emergency department visits in the past year Use of greater than two canisters of short-acting bronchodilators per month Difficulty perceiving airway obstruction or the severity of worsening asthma Low socioeconomic status or inner-city residence Illicit drug use Major psychosocial problems or psychiatric disease Comorbidities, such as cardiovascular disease or other chronic lung disease3

Source: National Asthma Education and Prevention Program Expert Panel Report 3, Guidelines for the Diagnosis and Management of Asthma. US Department of Health and Human Services, National Institutes of Health, National Heart, Lung, and Blood Institute, NIH Publication Number 08-5846, October, 2007

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Respiratory Clinical Pearls Interestingly, the triggers that cause the most trouble are dust mites and the dreaded cockroach. How so? It has been shown that dust mites are microscopic creatures that live quite nicely in a moist and warm environment. They tend to thrive in carpets, upholstery, stuffed animals, bedding, and curtains. It is easy to see why symptoms become worse at night when dust mites may be the contributing factor. On the other hand, the cockroach is known for roaming the house at night, looking for food and water to survive. It is the cockroach droppings that are of most concern. Once cockroach droppings dry, they become a powder-like substance that is easily inhaled. Consider a 9-month-old toddler who is still crawling: the area between the child’s breathing distance and the cockroach dropping is significant compared to the adult who is standing upright and at a distance from the floor. Our respiratory message should be clear about the importance of reducing cockroach inhabitation, particularly in homes where young children live. When sharing this message, we can point out tips to a family that will help reduce the food and water sources of cockroaches. This could be as simple as making sure that the house is cleaned routinely, particularly the kitchen and bathroom. Food should be put away in airtight storage containers (this decreases cockroaches’ source of food), food crumbs are cleaned promptly, and the home is vacuumed or dust mopped daily. In many instances, these very basic steps are just enough to decrease asthma triggers, which allow a child to go symptomfree for years.

Inasmuch as asthma and severe asthma exacerbation are the same disease, severe asthma exacerbation is the severe form of asthma. Patients who have previous history of intensive care unit (ICU) admission with or without intubation, peak flow less than 10% from baseline despite treatment, and recent or current use of inhaled corticosteroids are at increased risk for developing severe or persistent severe asthma exacerbation.4 Asthma Severity The NAEPP classifies asthma severity when the patient is well controlled. The guidelines uses a stepwise approach to managing asthma. This will be discussed in detail in the section on treatment. There are four prongs to this classification system:

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Intermittent Asthma

Persistent Asthma

Intermittent

Mild

Moderate

Severe

Step 1

Step 2

Step 3 or step 4

Step 5 or step 6

If this system is to work well, it recognizes that severity and control are similar. The goal is to initiate therapy based on asthma severity and to either step up therapy to control symptoms or step down therapy when symptoms are under control.2 Figures 3-2 and 3-3 illustrate the stepwise chart for managing asthma in children 0–4 years, 5–11 years, and 12 years to adult. DISTINGUISH

Some conditions mimic the signs and symptoms of asthma. Care must be taken to differentiate these conditions from asthma:

Allergic rhinitis and sinusitis Foreign body in trachea or bronchus Vocal cord dysfunction Vascular rings or laryngeal webs Laryngotracheomalacia, tracheal stenosis, or bronchostenosis Viral bronchiolitis or obliterative bronchiolitis Cystic fibrosis Bronchopulmonary dysplasia Heart disease Recurrent cough not due to asthma Swallowing defect or gastroesophageal reflux (GERD)3

NAEPP guidelines point out the following when distinguishing the difference between asthma and other diagnosis: • Vocal cord dysfunction can present like asthma and can coexist with asthma; however, asthma medication cannot treat this condition. To make a conclusive diagnosis of asthma, spirometry measurements should be done. If spirometry shows evidence of suspected vocal cord dysfunction, then either an indirect or direct visualization of the vocal cords during an attack should be done.

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• Gastroesophageal reflux disease (GERD) may coexist with asthma, and, similarly to vocal cord dysfunction, there must be clear evidence to distinguish GERD from asthma. The guidelines further note that although spirometry is the gold standard for diagnosing a patient with asthma, this becomes a challenge in children ages 0–4 years because it is difficult to obtain objective pulmonary function measurements. The guidelines also caution against prolonging asthma therapy in this group as well as underdiagnosing asthma in this group.3 Asthma guidelines recommend that children are referred to an asthma specialist when it becomes difficult to confirm asthma as the diagnosis. RESEARCH

Environmental exposures to allergens and irritants may cause or exacerbate asthma,12 and controlling these exposures is an important component in managing asthma.13,14,15 Yet a national survey of parents found that over half (51%) of the environmental actions the parents initiated to control their child’s asthma triggers were unlikely to be beneficial based on current NAEPP guidelines, suggesting a need to improve awareness about recognized methods to address triggers.16 Moreover, parents of children with asthma often overlooked key measures like banning smoking from the home and shutting windows to keep pollen out. The EPA’s first-ever National Survey on Environmental Management of Asthma and Children’s Exposure to Environmental Tobacco Smoke also indicates that much more work needs to be done to improve individual awareness, knowledge, and action on environmental management of triggers. Eliminating smoking and exposure to tobacco smoke (ETS) are critical for controlling asthma. Compared with nonsmokers who have asthma, active smokers have more severe asthma symptoms, accelerated decline in lung function, and impaired short-term therapeutic responses to corticosteroids. Adolescents who smoke have four times the risk of developing asthma as nonsmoking youth. ETS exposure can trigger asthma attacks and make asthma symptoms more severe. Moreover, ETS exposure can cause asthma in children who have not previously exhibited symptoms.

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s

Chapter 3 Asthma

Step up if needed (first check inhaler technique, adherence, environmental control, and comorbid conditions)

Access control

Step down if possible (and asthma is well controlled at least 3 months)

Step 4 Step 3 Step 2 Step 1

Children 0–4 Years of Age

Intermittent Asthma Preferred

SABA PRN

Alternative

Persistent Asthma: Daily Medication Consult with asthma specialist if step 3 care or higher Low-dose ICS

Medium-dose ICS

is

Medium-dose ICS + LABA or Montelukast

H L

Cromolyn or Montelukast Each Step: Patient Education and Environmental Control

Quick-Relief Medication

• SABA as needed for symptoms. Intensity of treatment depends on severity of symptoms. • With viral respiratory symptoms: SABA q 4–6 hours up to 24 hours (longer with physician consult). Consider short course of oral systemic corticosteroids if exacerbation is severe or patient has history of previous severe exacerbations. Caution: Frequent use of SABA may indicate the need to step up treatment. See text for recommendations on initiating daily long-term-control therapy.

Children 5–11 Years of Age

Intermittent Asthma Preferred

Alternative

SABA PRN

Persistent Asthma: Daily Medication Consult with asthma specialist if step 4 care or higher Low-dose ICS

Cromolyn, LTRA, Nedocromil, or Theophylline

Low-dose ICS + LABA, LTRA, or Theophyline OR Medium-dose ICS

is

Medium-dose ICS + LABA

H L

Medium-dose ICS + LTRA or Theophylline

H L

Each Step: Patient Education, Environmental Control, and Management of Comorbidities Steps 2–4: Consider subcutaneous allergen immunotherapy for patients who have persistent, allergic asthma. Quick-Relief Medication

• SABA as needed for symptoms. Intensity of treatment depends on severity of symptoms: up to 3 treatments at 20-minute intervals as needed. Short course of oral systemic corticosteroids may be needed. Caution: Increasing use of SABA or use >2 days a week for symptom relief (not preventin of EIB) generally indicates inadequate control and the need to step up treatment.

Figure 3-2 NAEPP Stepwise Chart: 0–4 Years and 5–11 Years Adapted from: National Asthma Education and Prevention Program Expert Panel Report 3, Guidelines for the Diagnosis and Management of Asthma. US Department of Health and Human Services, National Institutes of Health, National Heart, Lung, and Blood Institute, NIH Publication Number 08-5846, October, 2007

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ions)

65

g Step 6 Notes

Step 5

Step 4

n r

is required. Consider consultation at step 2. High-dose ICS + LABA or Montelukast

High-dose ICS + Oral corticosteroids ICS + LABA or Montelukast

ult).

on

n r

is required. Consider consultation at step 3.

ma.

nts at

High-dose ICS + LABA or Montelukast

High-dose ICS + LABA + oral corticosteroids

High-dose ICS + LTRA or Theophylline

High-dose ICS + LTRA or Theophylline + oral corticosteroids

• The stepwise approach is meant to assist, not replace, the clinical decisionmaking required to meet individual patient needs. • If an alternative treatment is used and response is inadequate, discontinue it and use the preferred treatment before stepping up. • If clear benefit is not observed within 4–6 weeks, and patient’s/family’s medication technique and adherence are satisfactory, consider adjusting therapy or an alternative diagnosis. • Studies on children 0–4 years are limited. Step 2 preferred therapy is based on Evidence A. All other recommendations are based on expert opinion and extrapolation from studies in older children. • Clinicians who administer immunotherapy should be prepared and equipped to identify and treat anaphylaxis that may occur. Key: Alphabetical listing is used when more than one treatment option is listed within either preferred or alternative therapy. ICS, inhaled corticosteroid; LABA, inhaled long-acting beta2-agonist; LTRA, leukotriene receptor antagonist, oral corticosteroids, oral systemic corticosteroids; SABA, inhaled short-acting beta2-agonist. • The stepwise approach is meant to assist, not replace, the clinical decisionmaking required to meet individual patient needs. • If an alternative treatment is used and response is inadequate, discontinue it and use the preferred treatment before stepping up. • Theophylline is a less desirable alternative due to the need to monitor serum concentration levels. • Steps 1 and 2 medications are based on Evidence A. Step 3 ICS and ICS plus adjunctive therapy are based on Evidence B for efficacy of each treatment and extrapolation from comparator trials in older children and adults—comparator trials are not available for this age group; steps 4–6 are based on expert opinion and extrapolation from studies in older children and adults. • Immunotherapy for steps 2–4 is based on Evidence B for house-dust mites, animal danders, and pollens; evidence is weak or lacking for molds and cockroaches. Evidence is strongest for immunotherapy with single allergens. The role of allergy in asthma is greater in children than adults. • Clinicians who administer immunotherapy should be prepared and equipped to identify and treat anaphylaxis that may occur. Key: Alphabetical listing is used when more than one treatment option is listed within either preferred or alternative therapy. ICS, inhaled corticosteroid; LABA, inhaled long-acting beta2-agonist; LTRA, leukotriene receptor antagonist; SABA, inhaled short-acting beta2-agonist.

.

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Assessing severity and initiating treatment for patients who are not currently taking long-term control medications Classification of Asthma Severity ≥ 12 years of age Persistent Components of Severity Impairment Normal FEV1/FVC: 8–19 yr 85% 20–39 yr 80% 40–59 yr 75% 60–80 yr 70%

Intermittent

Mild

Moderate

Severe

Symptoms

£ 2 days/week

> 2 days/week but not daily

Daily

Throughout the day

Nighttime awakenings

£ 2¥/month

3–4¥/month

> 1¥/week but not nightly

Often 7¥/week

Short-acting beta2agonist use for symptom control (not prevention of EIB)

£ 2 days/week

> 2 days/week but not daily, and not more than 1¥ on any day

Daily

Several times per day

Interference with normal activity

None

Minor limitation

Some limitation

Extremely limited

Lung function

Normal FEV1 between exacerbations FEV1 > 80% predicted FEV1/FVC normal

FEV1 > 80% predicted FEV1/FVC normal

FEV1 > 60% but < 80% predicted FEV1/FVC reduced 5%

FEV1 < 60% predicted FEV1/FVC reduced > 5%

Risk

Exacerbations requiring oral systemic corticosteroids

Recommended Step for Initiating Treatment (See “Stepwise Approach for Managing Asthma” for treatment steps.)

0–1/year (see note)

≥ 2/year (see note)

Consider severity and interval since last exacerbation. Frequency and severity may fluctuate over time for patients in any severity category. Relative annual risk of exacerbations may be related to FEV1. Step 1

Step 2

Step 3

Step 4 or 5

and consider short course of oral systemic corticosteroids In 2–6 weeks, evaluate level of asthma control that is achieved and adjust therapy accordingly.

Figure 3-3 NAEPP Stepwise Chart: 12 Years to Adult Adapted from: National Asthma Education and Prevention Program Expert Panel Report 3, Guidelines for the Diagnosis and Management of Asthma. US Department of Health and Human Services, National Institutes of Health, National Heart, Lung, and Blood Institute, NIH Publication Number 08-5846, October, 2007

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Key: EIB, exercise-induced bronchospasm; FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity; ICU, intensive care unit Notes: • the stepwise approach is meant to assist, not replace, the clinical decisionmaking required to meet individual patient needs. • Level of severity is determined by assessment of both impairment and risk. Assess impairment domain by patient’s/ caregiver’s recall of previous 2–4 weeks and spirometry. Assign severity to the most severe category in which any feature occurs. • At present, there are inadequate data to correspond frequencies of exacerbations with different levels of asthma severity. In general, more frequent and intense exacerbations (e.g., requiring urgent, unscheduled care, hospitalization, or ICU admission) indicate greater underlying disease severity. For treatment purposes, patients who had ≥ 2 exacerbations requiring oral systemic corticosteroids in the past year may be considered the same as patients who have persistent asthma, even in the absence of impairment levels consistent with persistent asthma.

.

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Finally, a study was released in May 2007 by the National Center for Healthy Housing (NCHH) of 67 Phoenix, Arizona, families who received help from a research team that included the Phoenix Children’s Hospital, the City of Phoenix, and the NCHH to follow simple steps to reduce asthma triggers in the home. The measures included vacuuming often using a HEPA filter; using zippered, allergen-resistant mattresses and pillow covers; and keeping food stored in tightly sealed containers. They found that 96% of the parents reported that the health of their children with asthma had improved. The researchers observed at the start of the project that 52% to 69% of the homes had dust in carpets, bedding, and in the heating and cooling system; poor general housekeeping; musty smell; and cockroach infestation.17 NAEPP’s guidelines, Expert Panel Report 3 (2007), made recommendations on how to improve asthma care in the United States. Asthma is the third leading cause of hospitalization in the United States and accounts for almost 500,000 emergency room visits, of which roughly 10% result in death each year. The guidelines reaffirm the recommendations of the previous expert panel reports. The 2007 report highlights some of the recommended key clinical activities for the diagnosis and management of asthma. This report places heavy emphasis on patient education, control of environmental factors, and recognition of comorbid conditions that affect asthma. It further addresses particular concerns of children ages 5 years through 11 years that were not adequately addressed in previous reports. As in previous reports, a stepwise approach is still the current thinking for managing asthma. As discussed earlier in the section that describes it, asthma severity and control go hand in hand. Accordingly, the NAEPP’s goal is asthma control, which aims to do the following: Reduce Impairment • • • •

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Prevent chronic symptoms Reduce use of short-acting bronchodilators Maintain near-normal pulmonary function Meet patient and families’ expectations of and satisfaction with asthma care

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Reduce Risk • Prevent future asthma attacks • Prevent loss of lung function • Provide optimal medication with minimal drug side effects TREATMENT

Managing asthma is an ongoing skill that all respiratory therapists will possess throughout their career. Patients with severe asthma exacerbation typically will be admitted to the hospital for further asthma management. As the NAEPP guidelines suggest, the same four components used in long-term asthma management will also be used to manage a child with severe asthma exacerbation with or without intubation. Children who arrive in the emergency room and are diagnosed with asthma exacerbation require our heightend attention. As respiratory therapists, we are interested in any history of intubation, intensive care admission, two or more recent hospitalizations in the past 12 months, or 3 or more emergency room visits within the past year. The NAEPP guideline reminds us that we should never underestimate the severity of an exacerbation because it could be life threatening. See Figure 3-4 for the NAEPP algorithm on Management of Asthma Exacerbations: Emergency Department and Hospital-Based Care. Delivery Devices Discussed in the NAEPP Guidelines • Arterial blood gas collection • An arterial blood gas is the standard to establish both ventilation and oxygenation. Patients with asthma exacerbation must be managed early in the course of their condition. • Oxygen therapy for a nonintubated patient with mild to moderate hypoxemia • 100% non-rebreather mask (see Figure 3-5) • The literature suggests the use of noninvasive ventilation has been shown to relieve acute hypoxemia. With this therapy the patient must be breathing spontaneously and have no evidence of impending respiratory failure (see Figure 3-6 for a picture of a noninvasive ventilator).

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Note: Patients are instructed to use quick-relief medications if symptoms occur or if PEF drops below 80 percent predicted or personal best. If PEF is 50–79 percent, the patient should monitor response to quick-relief medication carefully and consider a clinician. If PEF is below 50 percent, immediate care is usually required. In the urgent or emergency care setting, the following parameters describe the severity and likely clinical course of an exacerbation. Symptoms and Signs

Initial PEF (or FEV1)

Clinical Course

Mild

Dyspnea only with activity (assess tachypnea in young children)

PEF ≥ 70 percent predicted or personal best

Usually cared for at home Prompt relief with inhaled SABA Possible short course of oral systemic corticosteroids

Moderate

Dyspnea interferes with or limits usual activity

PEF 40–69 percent predicted or personal best

Usually requires office or ED visit Relief from frequent inhaled SABA Oral systemic corticosteroids; some symptoms last for 1–2 days after treatment is begun

Severe

Dyspnea at rest; interferes with conversation

PEF < 40 percent predicted or personal best

Usually requires ED visit and likely hospitalization Partial relief from frequent inhaled SABA Oral systemic corticosteroids; some symptoms last for > 3 days after treatment is begun Adjunctive therapies are helpful

Subset: Life threatening

Too dyspneic to speak; perspiring

PEF < 25 percent predicted or personal best

Requires ED/hospitalization; possible ICU Minimal or no relief from frequent inhaled SABA Intravenous corticosteroids Adjunctive therapies are helpful

Key: ED, emergency department; FEV1, forced expiratory volume in 1 second; ICU, intensive care unit; PEF, peak expiratory flow; SABA, short-acting beta2-agonist. Figure 3-4 NAEPP Guidelines for Severe Asthma Exacerbations: Emergency Department and Hospital-Based Care Adapted from: National Asthma Education and Prevention Program Expert Panel Report 3, Guidelines for the Diagnosis and Management of Asthma. US Department of Health and Human Services, National Institutes of Health, National Heart, Lung, and Blood Institute, NIH Publication Number 08-5846, October, 2007

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Figure 3-5 Child nonrebreather mask

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Figure 3-6 Noninvasive positive pressure ventilator

• Short-acting beta2-agonist (SABA) • Figure 3-7 shows the NAEPP recommended dosages of drugs for asthma exacerbations • SABA can be given with a small volume nebulizer (SVN; see Figure 3-8) • SABA can be given with a metered dose inhaler (MDI; see Figure 3-9) with a holding chamber—this is highly recommended even for adult patients.

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Dosage Medication

Child Dose*

Adult Dose

Comments (not all inclusive)

Inhaled Short-Acting Beta2-Agonists (SABA) Albuterol Nebulizer solution (0.63 mg/3 mL, 1.25 mg/3 mL, 2.5 mg/3 mL. 5.0 mg/mL)

0.15 mg/kg (minimum dose 2.5 mg) every 20 minutes for 3 doses than 0.15–0.3 mg/kg up to 10 mg every 1–4 hours as needed, or 0.5 mg/kg/hour by continuous nebulization.

2.5–5 mg every 20 minutes for 3 doses, then 2.5–10 mg every 1–4 hours as needed, or 10–15 mg/hour continuously.

Only selective beta2-agonists are recommended. For optimal delivery, dilute aerosols to minimum of 3 mL at gas flow of 6–8 L/min. Use large volume nebulizers for continuous administration. May mix with ipratropium nebulizer solution.

MDI (90 mcg/puff)

4–8 puffs every 20 minutes for 3 doses, then every 1–4 hours inhalation maneuver as needed. Use VHC, add mask in children < 4 years.

4–8 puffs every 20 minutes up to 4 hours, then every 1–4 hours as needed.

In mild-to-moderate exacerbations, MDI plus VHC is as effective as nebulized therapy with appropriate administration technique and coaching by trained personnel.

See albuterol dose; thought to be half as potent as albuterol on mg basis.

See albuterol dose.

Has not been studied in severe asthma exacerbations. Do not mix with other drugs.

See albuterol MDI dose.


Has not been studied in severe asthma exacerbations.

0.075 mg/kg (minimum dose 1.25 mg) every 20 minutes for 3 doses, then 0.075–0.15 mg every 1–4 hours as needed.

1.25–2.5 mg every 20 minutes for 3 doses, then 1.25–5 mg every 1–4 hours as needed.

Levalbuterol administered in one-half the mg dose of albuterol provides comparable efficacy and safety. Has not been evaluated by continuous nebulization.

MDI 945 mcg/puff)



Pirbuterol MDI (200 mcg/puff)

See albuterol MDI dose; thought to be half as potent as albuterol on a mg basis.


Has not been studied in severe asthma exacerbations.

Bitolterol Nebulizer solution 92 mg/mL) MDI (370 mcg/puff) Levalbuterol (R-albuterol) Nebulizer solution (0.63 mg/3 mL, 1.25 mg/0.5 mL, 1.25 mg/3 mL)

Systemic (Injected) Beta2-Agonists Epinephrine 1:1,000 (1 mg/mL)

0.01 mg/kg up to 0.3–0.5 mg every 20 minutes for 3 doses sq.

0.3–0.5 mg every 20 minutes for 3 doses sq.

No proven advantage of systemic therapy over aerosol.

Terbutaline (1 mg/mL)

0.01 mg/kg every 20 minutes for 3 doses then every 2–6 hours as needed sq.

0.25 mg every 20 minutes for 3 doses sq.

No proven advantage of systemic therapy over aerosol.

Figure 3-7 NAEPP Drug Dosages for Asthma Management Adapted from: National Asthma Education and Prevention Program Expert Panel Report 3, Guidelines for the Diagnosis and Management of Asthma. US Department of Health and Human Services, National Institutes of Health, National Heart, Lung, and Blood Institute, NIH Publication Number 08-5846, October, 2007 (continues)

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Dosage

Medication

Child Dose*

Adult Dose

Comments (not all inclusive)

Anticholinergics Ipratropium bromide Nebulizer solution (0.25 mg/mL)

0.25–0.5 mg every 20 minutes for 3 doses, then as needed

0.5 mg every 20 minutes for 3 doses, then as needed

May mix in same nebulizer with albuterol. Should not be used as first-line therapy; should be added to SABA therapy for severe exacerbations. The addition of ipratropium has not been shown to provide further benefit once the patient is hospitalized.

MDI (18 mcg/puff)

4–8 puffs every 20 minutes as needed up to 3 hours

8 puffs every 20 minutes as needed up to 3 hours

Should use with VHC and face mask for children < 4 years. Studies have examined ipratropium bromide MDI for up to 3 hours.

Ipratropium with albuterol Nebulizer solution (each 3 mL vial contains 0.5 mg ipratropium bromide and 2.5 mg albuterol.)

1.5 mL every 20 minutes for doses, then as needed

3 mL every 20 minutes for doses, then as needed

May be used for up to 3 hours in the initial management of severe exacerbations. The addition of ipratropium to albuterol has not been shown to provide further benefit once the patient is hospitalized.

MDI (Each puff contains 18 mcg ipratropium bromide and 90 mcg of albuterol.)

4–8 puffs every 20 minutes as needed up to 3 hours

8 puffs every 20 minutes as needed up to 3 hours

Should use with VHC and face mask for children < 4 years.

Systemic Corticosteriods (Apply to all three corticosteriods.) Prednisone Methylprednisolone Prednisolone

1 mg/kg in divided doses (maximum = 60 mg/day) until PEF is 70 percent of predicted or personal best

40–80 mg/day in 1 or 2 divided doses until PEF is 70 percent of predicted or personal best

For outpatient “burst,” use 40–60 mg in single or 2 divided doses for a total of 5–10 days in adults (children: 1–2 mg/kg/day maximum 60 mg/day for 3–10 days).

* Children £ 12 years of age Key: ED, emergency department; MDI, metered-dose inhaler; PEF, peak expiratory flow; VHC, valved holding chamber Notes: • There is no known advantage for higher doses of corticosteroids in severe asthma exacerbations, nor is there any advantage for intravenous administration over oral therapy provided gastrointestinal transit time or absorption is not impaired. • The total course of systemic corticosteroids for an asthma exacerbation requiring an ED visit of hospitalization may last from 3 to 10 days. For corticosteroid courses of less than 1 week, there is no need to taper the dose. For slightly longer courses (e.g., up to 10 days), there probably is no need to taper, especially if patients are concurrently taking ICSs. • ICSs can be started at any point in the treatment of an asthma exacerbation. Figure 3-7 (continued)

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Figure 3-8 Small volume nebulizer with pediatric mask

• Either SABA with SVN or MDI can be given to patients through the ventilator circuit. Figure 3-10 depicts SVN and MDI in line with a ventilator. • Continuous nebulizer therapy with SABA • The literature supports the use of continuous nebulization versus intermittent nebulization. Heinrich Werner reports in his findings that continuous nebulization seems to be superior to that of intermittent nebulization.6 He further states that according to the study results, children respond better when they are allowed to

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Figure 3-9 MDI with pediatric mask and holding chamber

sleep during the treatment.6 Additionally, Dr. Werner indicates that the use of continuous nebulization may also be more cost effective than intermittent nebulization. Figure 3-11 shows continuous nebulization setup for a nonintubated patient. • The NAEPP recommended dosage for continuous nebulization is 0.5 mg/kg per hour.2 • Continuous nebulization with SABA and anticholinergics can be given in line with the ventilator circuit to a patient on mechanical

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Figure 3-10 Small volume nebulizer in-line with ventilator circuit

ventilators (Figure 3-12). Keep in mind some mechanical ventilators have flow sensors, so care must be made to assure a properly functioning mechanical ventilator while administering medication in the ventilator circuit. • Remember: Each of these units may vary slightly in how you calculate the dosage needed per hour to administer the SABA—keep this in mind. Figure 3-13 shows a variety of nebulizers that can be used to give continuous nebulizer therapy.

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Figure 3-11 Continuous nebulizer setup for nonintubated patient

• Helium-oxygen therapy (heliox therapy) • Heliox has been well researched in the treatment of asthma. Heliox promotes laminar flow across narrowed airways. Recall in earlier discussions, there is an element of bronchoconstriction that causes this squeezing sensation of the muscles surrounding the airway. As the airway narrows, there is a subsequent decrease in airflow through the airway. According to Gupta et al., helium has been shown to improve gas exchange in patients with asthma by lowering airway resistance, improving gas flow, and improving gas exchange.18 Further, Gupta et al. report that helium has been shown to convert areas of turbulent flow within the airway to areas of laminar flow. This conversion is what supports the improved gas exchange seen in patients using helium therapy.

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Figure 3-12 Continuous nebulizer setup for intubated patient

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Figure 3-13 Several different nebulizer units

• Commercially, helium and oxygen are available in mixtures of 80% helium and 20% oxygen (80–20), 70% helium and 30% oxygen (70–30), and 60% helium and 40% oxygen (60–40).19 • When administering heliox, it must be provided in a closed environment. The following are examples of heliox delivery devices: • Heliox can be provided with a nonrebreather mask. Recently, a mask was designed specifically for the delivery of heliox. Figure 3-14 shows a specific type of heliox mask used to deliver heliox. • Heliox can be given in line with a mechanical ventilator— although very few ventilators are calibrated to accept heliox as a source gas. • Avoid entraining room air because this will dilute your heliox mixture.

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O2 tubing oxygen blender

81

3-way adapter

O2 tubing to adapter Tubing to Heliox tank

Figure 3-14 Heliox mask

• Remember: Check the ventilator specification to determine whether heliox can be administered through the ventilator. Historically, the Servo 300 had been one of the very few ventilators that would accept heliox as a source gas.

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• At the time of this writing, the Servo 300 is no longer being manufactured and has been replaced with the Servo i. • When placing heliox in line with a mechanical ventilator, replace the air hose with the hose connected to your heliox tank. Additionally, there should be at least two heliox tanks connected together at the bedside so that when it is time to change the tank, one is readily available. • Remember: There is a limitation on using either mixture for the treatment of severe asthma exacerbation when there is a requirement for oxygen greater than 40%. Food for Thought Now that you understand that helium is a very light gas and has the ability to rise to the top, consider this clinical situation. A respiratory therapist received an order to provide heliox to a baby in a mist tent. He attempted to convince the new physician that heliox is to be given in a closed environment, but the physician insisted that heliox be set up in this manner. The end result was that the baby required more aggressive therapy. Heliox is a light gas that rises to the top while the baby lies at the bottom of the mist tent. During this brief period, the baby did not receive the care due; in fact, attempting this ill-conceived therapy may have delayed appropriate care. As a respiratory therapist, it is important to understand the effects of the therapy being recommended and to always be in a position to educate the medical team regarding treatment options in your area of expertise.

• Anticholinergic • NAEPP guidelines recommend ipratropium bromide (Atrovent) in the treatment of asthma exacerbation (see Figure 3-7). • Corticosteroids • NAEPP guidelines recommend systemic corticosteroids along with SABA to speed up the recovery process (see Figure 3-7). • Other drugs that provide bronchodilator effects • Intravenous magnesium sulfate has been shown to relax smooth muscles, causing bronchodilation. Magnesium sulfate does not compete with calcium at the site where calcium would bind with smooth muscles. • Ketamine has been shown to be a short-acting pentachlorophenol derivative that causes bronchodilation through an increase in

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catecholamine levels. This increase has been seen at the beta receptor sites and thus causes bronchial relaxation. • Mechanical ventilators • Patients with severe asthma exacerbation can be difficult to ventilate due to poor chest wall compliance, high airway resistance, increased secretions, and mucosal edema.19,20 • Air trapping and auto-PEEP are routinely seen in patients with severe asthma exacerbation and should be avoided when possible. Summary

✔✔ Asthma is a chronic, inflammatory condition characterized by increased mucus production, increased swelling of mucosa tissue, and bronchial smooth muscle constriction. ✔✔ Asthma varies in its level of severity: it can be intermittent, mild persistent, moderate persistent, and severe persistent. ✔✔ Asthma affects almost 22 million Americans. ✔✔ Asthma affects almost 6 million children. ✔✔ Asthma causes about 2 million people to seek emergency room care annually. ✔✔ Asthma costs the United States nearly $6 billion a year in healthcare expenditures. ✔✔ Asthma is the main cause of school absenteeism and missed work in the United States. ✔✔ Asthma still causes nearly 5000 deaths each year. ✔✔ Asthma management requires controlling symptoms, decreasing triggers, and improving lung function. ✔✔ Asthma triggers can be grouped into three types: allergens (e.g., pet dander, cockroaches, mold, grass, tree pollen), irritants (e.g., perfumes, tobacco smoke, cleaning products), and physical conditions (e.g., strong emotions, exercise, weather, viral infections). ✔✔ Asthma is often associated with rhinitis, sinusitis, and dermatologic eczema. ✔✔ Asthma’s number one symptom in children is coughing. Other classic symptoms include shortness of breath, chest tightness, and wheezing.

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Respiratory Clinical Pearls Patient Presentation

Action

2-month-old with mild expiratory wheezes

• Provide oxygen via nasal cannula. • Provide bronchodilator with 2.5 mg albuterol via face mask held close to the child’s face. This may have to be given 3 times at least 20 minutes apart. • Provide close observation.

Respiratory rate = 75 Heart rate = 160 SpO2 = 92% Labored breathing Retractions noted 8-year-old with fine crackles (some say fine rales) with harsh expiratory wheezes Respiratory rate = 35 Heart rate = 120 Choppy sentences while speaking

• Provide oxygen via pediatric nonrebreather mask. • Recommend an arterial blood gas at this time to determine adequate ventilation and oxygenation. • Recommend a chest x-ray. • Prepare for possible intubation if patient begins to fatigue.

Very labored breathing Sternal retractions SpO2 = 85% FEV1 of less than 70% 17-year-old known asthmatic who has received 3

• Recommend a meter dose inhaler with a spacer with 2 puffs of albuterol as needed. • Recommend a long-acting bronchodilator/steroid of corticosteroids and is preparing for discharge. Patient combination: Advair 100 mcg/50 mcg, 2 puffs twice had been noncompliant with respiratory medications. You daily. • Seek reasons for noncompliance. are asked to do a respiratory consult prior to discharge. • Review MDI/DPI technique • Review peak flowmeter use. • Educate patient again on the causes of asthma, asthma triggers, and ways to reduce emergency room visits. nebulizer treatments with 2.5 mg albuterol and 1 dose

References 1. American Lung Association. (2007, December). Fact sheet: Diseases A–Z. Retrieved February 20, 2008, from http:// www.lungusa.org/site/apps/nlnet/content3 2. American Academy of Pediatrics and American College of Emergency Physicians. (2004). The pediatric emergency medicine resource (4th ed.) Sudbury, MA: Jones and Bartlett Publishers.

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3. National Asthma Education and Prevention Program (NAEPP). (2007). Expert panel report 3: Guidelines for the diagnosis and management of asthma. Bethesda, MD: National Institutes of Health (NIH Pub. No. 08-5846). Updates available at http://www.nhlbi.nih.gov/guidelines/asthma/asthsumm.htm 4. Schwarz, A. (2007, December). Severe asthma exacerbation. Retrieved February 20, 2008, at http://www.emedicine. com/specialties.htm 5. Werner, H. (2001). Severe asthma exacerbation in children. Chest, 119, 1913–1929. 6. U.S. Department of Health and Human Services. (2000, November). Healthy people 2010. Washington, DC: U.S. Government Printing Office. 7. Akinbami, L. (2006, November). Asthma prevalence, health care use and mortality: United States. 2003–05. Retrieved June 1, 2007, from http://www.cdc.gov/nchs/products/pubs/pubd/hestats/ashtma03-05/asthma03-05.htm 8. United States Environmental Protection Agency. (2003). Fact sheet: National survey on environmental management of asthma and children’s exposure to environmental tobacco smoke. Retrieved May 30, 2007, from http://www.epa.gov/ smokefree/pdfs/survey_fact_sheet.pdf 9. Joseph, C., Williams, L., Ownby, D., Saltzgaber, J., & Johnson, C. (2006). Applying epidemiologic concepts of primary, secondary, and tertiary prevention to the elimination of racial disparities in asthma. Journal of Allergy Clinical Immunology, 117 (2), 233–240. 10. Lieu, T., Lozano, P., Finkelstein, J., Chi, F., Jensvold, N., & Capra, A. (2002). Racial/ethnic variation in asthma status and management practices among children in managed Medicaid. Pediatrics, 109, 857–865. 11. American Academy of Allergy Asthma & Immunology. (n.d.). Asthma statistics. Retrieved June 1, 2007, from http:// www.aaaai.org/media/resources/media_kit/asthma_statistics.stm 12. Institute of Medicine. (2000). Clearing the air: Asthma and indoor air exposures. Washington, DC: Institute of Medicine, National Academy Press. 13. Crain, E., Walter, M., O’Connor, G., Mitchell, H., Gruchalla, R., Kattan, M., et al. (2002). Home and allergic characteristics of children with asthma in seven U.S. urban communities and design of an environmental intervention: The inner-city asthma study. Environmental Health Perspectives, 110 (1), 939–945. 14. Morgan, W., Crain, E., Gruchalla, R., O’Connor, G., Kattan, M., Evans, R., III, et al. (2004). Results of a home-based environmental intervention among urban children with asthma. New England Journal of Medicine, 351(11), 1068–1080. 15. Takaro, T., Krieger, J., & Song, L. (2004). Effect of environmental interventions to reduce exposure to asthma triggers in homes of low-income children in Seattle. Journal of Exposure Analysis and Environmental Epidemiology, 14 (Suppl. 1), S133–S143. 16. Cabana, M. D., Slish, K. K., Lewis, T. C., Brown, R. W., Nan, B., Lin, X., et al. (2004, August). Parental management of asthma triggers within a child’s environment. Journal of Allergy and Clinical Immunology, 114 (2), 352–357. 17. National Center for Healthy Housing. (n.d.). Phoenix healthy homes demonstration project. Retrieved March 28, 2008, from http://www.centerforhealthyhousing.org/html/projects_research.htm#Phoenix2 18. Gupta, V., Grayck, E., & Cheifetz, I. (2004). Heliox administration during high-frequency jet ventilation augments carbon dioxide clearance. Respiratory Care, 49 (9), 1038–1044. 19. Pilbeam, S., & Cairo, J. (2006). Mechanical ventilation: Physiological and clinical applications (4th ed.). St. Louis, MO: Mosby Elsevier. 20. MacIntyre, N., & Branson, R. (2001). Mechanical ventilation. Philadelphia: Saunders.

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4

Chronic Lung Disease of the Newborn Chapter Outline DEFINE • Define chronic lung disease of the newborn (CLD) • Discuss who is affected by chronic lung disease of the newborn DESCRIBE • Describe the clinical presentation of chronic lung disease of the newborn • Describe the difference stages of chronic lung disease of the newborn DISTINGUISH • Distinguish chronic lung disease of the newborn from other conditions RESEARCH • Relevant research on chronic lung disease of the newborn

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TREATMENT • Treatment options in the care of chronic lung disease of the newborn patients • Respiratory therapist’s role in the management of chronic lung disease of the newborn patients

Key Terms Bronchodilator Chronic lung disease Chronic lung disease of the newborn (CLD) Chronic obstructive pulmonary disease Corticosteroids Nebulizer therapy Obstructive sleep apnea Oxygen therapy Saturations Surfactant

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INTRODUCTION

You have now acquired 2 years of experience as a respiratory therapist, and during this time, you have spent much of it with adult patients who have probably been diagnosed with chronic obstructive pulmonary disease (COPD). In the time that you will spend understanding neonatal/ pediatric respiratory care, you will encounter a little patient that reminds you of a COPD patient. DEFINE

Chronic lung disease of the newborn (CLD), also historically known as bronchopulmonary dysplasia (BPD), was first described by Northway et al. in 1967 as “a chronic respiratory disease that developed in premature infants exposed to mechanical ventilation and oxygen supplementation.”1 In 2001, a workshop conducted by the National, Heart, Lung, and Blood Institute (NHLBI) proposed a severity-based definition for infants younger than 32 weeks.2 This definition more accurately defined CLD:4 Mild BPD was defined as a need for supplemental oxygen for greater than or equal to 28 days but not at 36 weeks postmenstrual age or discharge; moderate BPD was defined as oxygen for greater than or equal to 28 days plus treatment with less than 30% oxygen at 36 weeks postmenstrual, and severe BPD was defined as oxygen for greater than or equal to 28 days plus greater than or equal 30% oxygen and/or positive pressure at 36 weeks postmenstrual. Who Is Affected by CLD? NHLBI reports that between 5,000 to 10,000 babies born each year will develop, CLD.3 Additionally, Eugenio Baraldi and Marco Filippone suggest that there are nearly 60,000 infants born each year in the United States under 1500 grams (about 3.5 pounds), and about 20% of them will develop CLD.1 DESCRIBE

Chronic lung disease of the newborn can be described as a significant lung change in a premature infant who is diagnosed with respiratory

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distress syndrome (RDS), requiring mechanical ventilation and/or high concentrations of inspired oxygen. This change results in the potential for impaired gas exchange, lung collapse, inflammation to the lung tissue, and overall pulmonary dysfunction. The following are classic signs of CLD:5 • History of prematurity that required the use of mechanical ventilation or the inability to wean from the ventilator • Oxygen dependency • Tachypnea, retractions, nasal flaring • Feeding intolerance • Poor tolerance to being touched • Breath sounds that indicate crackles and diminished air entry • More susceptible to lung infections, especially respiratory syncytial virus (RSV) • Respiratory syncytial virus itself is a medium-sized RNA virus and is classified as a paramyxovirus.5,6 RSV begins in the nasal epithelial cells and then replicates itself in the host cell, ultimately destroying the host cell, giving it the ability to reproduce in uninfected cells. • Frequent visits to the hospital before the age of 2 years CLD, as described by Kacmarek et al. (2005), can be categorized in stages based on the infant’s age and the severity of the condition:5 • Stage 1 • Occurs during the first 3 days of life • Chest x-ray shows a ground-glass appearance and air bronchograms • Stage 2 • Occurs at about 4 days up to 10 days of life • Formation of hyaline membrane • Granular opacification of the lungs, which makes it difficult to distinguish the heart borders • Stage 3 • Occurs at 10 to 20 days of life • Transition from acute to the chronic phase of CLD

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• Lung “whiteout” with multiple small cysts on chest x-ray • Alveolar emphysema and interstitial fibrosis • Evidence of congestive heart failure • Stage 4 • Occurs after 28 days of life • Large, irregular cysts on chest x-ray • Hyperinflation, flattened diaphragm, and evidence of atelectasis • Thickened alveolar walls and increased diffusion gradient • Prominent ventilation and perfusion mismatching • Slow wean from mechanical ventilation DISTINGUISH

Care must be made to distinguish CLD from other chronic respiratory illnesses. Asthma and bronchiolitis can present with similar clinical symptoms in children under 2 years. In children over two years, gastric esophageal reflux is another condition that mimics asthma. A careful medical history with concurrent physical examination and required laboratory testing will help to determine the appropriate diagnosis. CLD must be distinguished from the following: • Asthma—a chronic inflammation of the airways with reversible episodes of obstruction caused by an increased reaction of the airways to various stimuli.7 • Bronchiolitis—an acute, highly infectious lower respiratory tract infection caused mainly by the respiratory syncytial virus (RSV).5 • Gastric esophageal reflux disease (GERD)—the regurgitation of stomach contents into the esophagus. This condition is more prevalent in children with a diagnosis of asthma. This condition worsens asthma symptoms. Children with CLD have difficulty with eating and are often placed on GERD precautions to monitor the potential for aspiration pneumonia. RESEARCH

Since Norway and his colleagues described CLD in 1967, there has been a plethora of research on CLD. Although Norway and his research team

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proposed that CLD was caused by the initiation of mechanical ventilation and the use of oxygen therapy in the preterm infant, this development occurred prior to the development and implementation of surfactant in the clinical setting. Current research suggests that there is a distinction between “new CLD” and “old CLD.”1,3 The pathophysiology of old CLD demonstrates significant airway injury, inflammation, and lung tissue fibrosis compared to the new CLD, in which there is less lung tissue fibrosis, less airway injury, less inflammation, and more uniform inflation.1,3 CLD is not as common as it once was, due in part to the use of better ventilator techniques, the use of steroids before birth, and the use of surfactant therapy.3 Infants who develop CLD tend to be premature, lack surfactant, have very low birth weight, and exhibit little to no lung injury at birth; however, they subsequently develop oxygen dependency over the course of their stay in the nursery. The goals of the workshop sponsored by NHLBI were to develop an accurate definition of CLD, review the literature, and make recommendations for future research. With respect to future research, the members of the NHLBI workshop suggest the following research priorities:3,6 • Understand the development biology of the lung structure • Understand how inflammation and injury are expressed by the developing lung • Establish a resource tissue bank • Develop new clinical tests for lung function in infants and children • Study genetic contribution to the development of CLD • Develop standards of care as a basis of clinical trials • Evaluate delivery room procedures and ventilation techniques • Evaluate nutrition, antioxidant, and anti-inflammatory interventions • Train physicians and physiologists with expertise in evaluating lung function in infants and children Although CLD is occurring less frequently, it continues to develop in 20% of low birth weight infants born in the United States. Infants with CLD utilize a considerable amount of healthcare services, making CLD one of the most chronic respiratory illnesses in children younger than 2 years old.3 Research suggests that the best method of treating children

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with CLD is to prevent it from occurring; however, if prevention fails, supportive therapy can help to diminish lung damage and improve overall pulmonary health in children with CLD. TREATMENT

Supportive therapy has been shown to be an effective means of treating patients with CLD. Therapeutics used to treat CLD includes oxygen therapy, nutritional support, pharmacology therapy, bronchopulmonary hygiene, and positive pressure ventilation. CLD is such a complex condition that it requires multiple treatment regimens in order to manage the chronic respiratory symptoms. The research states that treating CLD should be multifocused.8 Table 4-1 illustrates the various CLD treatment options that are available. One or more therapeutics may be used in the treatment of children with CLD. Proposed strategies for managing children with CLD will fall into the following categories: I. Prevention A. High risk birth—Research indicates that prevention of CLD is the ultimate goal; Walsh et al. conclude that there is a clear evidence that the use of betamethasone in high-risk mothers has been beneficial in the survival of very low birth weight infants.9 B. Antenatal steroids—Early administration of surfactant and gentle modes of mechanical ventilation have been shown to minimize lung injury.8 II. Ventilator and Oxygen Strategy A. Oxygen therapy—For severe CLD patients who remain on supplemental oxygen for more than 30 days. • Keep oxygen saturation in the range of 88% to 92% and a partial pressure of oxygen (PaO2) of 50–70 mm Hg. This is considered a conservative use of oxygen in which you strike a delicate balance between promoting adequate oxygenation and decreasing the potential for retinopathy of prematurity.8 • Nasal cannula at flows of ¼ liter per minute up to 2 liters per minute on a blender, keeping FiO2 between 22% and 40% to keep SpO2 between 88% and 92%.

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Table 4-1 CLD Treatment Options

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Type of Therapy

Application

Oxygen therapy Nasal cannula Low flow nasal cannula

Goal is to maintain oxygen as low as possible. Keep SpO2 greater than 92%. Given with a blender to control precise FiO2 Given with a low flow flowmeter if a blender is not available Regular neonatal and pediatric nasal cannulas are available in varying sizes. Figure 4-1 illustrates a small neonatal nasal cannula. Figure 4-2 illustrates a pediatric nasal cannula.

Heated, humidified high flow nasal cannula10,11,12

Used to avoid mechanical ventilation Used to wean patients from mechanical ventilation High flow nasal cannula has been compared to the use of nasal CPAP; although the mechanics of delivery is known, the actual amount of pressure to the airway is not fully understood10, 11, 12, 13 Figure 4-3 is an illustration of a high flow nasal cannula.

High flow oxygen and aerosol therapy

Tracheostomy collar Goal is to provide oxygen and humidity to the airway. Keep FiO2 as low as possible. Given with a blender in most nurseries. Close attention must be paid to CLD patients with tracheostomy tubes. Potential for respiratory infection Potential for mucus plugging Need for frequent suctioning Figure 4-4 is an illustration of a tracheostomy collar on an infant

Mechanical ventilation7 Ventilator strategy includes settings that would maintain adequate PaCO2 and PaO2.

Keep PaCO2 between 40 to 50 mm Hg; may be higher for CLD. Keep PaO2 between 60 to 80 mm Hg. Keep SpO2 between 90% to 95% with low oxygen requirements.

Weaning from mechanical ventilation13

The use of nasal CPAP The use of high flow nasal cannula

Nutritional support

Adequate nutrition aids in the healing of damaged lung tissue.

Pharmacology therapy

Bronchodilator therapy with beta agonist has been shown to help in managing bronchoconstriction. Inhaled steroids help manage airway inflammation. Cromolyn sodium is used to prevent mast cell rupture. Antibiotics for respiratory infections Diuretics for fluid management

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Figure 4-1 Neonatal nasal cannula

Figure 4-2 Pediatric nasal cannula

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Figure 4-3 High humidity nasal cannula

Figure 4-4 Tracheostomy collar

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• High flow nasal cannula at flows of greater than 2 liters per minute, up to 6 liters per minute on a blender, keeping FiO2 between 22% to 40% to keep PaO2 of 50–70 mm Hg and SpO2 88% to 92%. • Although high flow nasal cannulas have become routine therapy in many neonatal and pediatric units, it is necessary to describe how the high flow nasal cannula gained its usefulness. By definition, high flow therapy is the delivery of high inspired gas flow that generally exceeds peak inspiratory demand. It is accomplished by warming and humidifying the dry gas at body temperature. Although this concept is not new, the use of high flows with a nasal cannula is new.14 Waugh et al. evaluated two devices for use in providing high flow therapy through a nasal cannula. Both the Salter lab device and the Vapotherm device met the minimum standards for humidification at the high flows. The goal of using high flow nasal cannula is to provide oxygen liter flows greater the conventional 6 liters per minute. In the clinical setting, we conveniently compare high flow nasal cannula to the use of nasal CPAP; however, a word of caution: the research has not yet established conclusive evidence of measured flow rates in relation to actual pressures to the airway. Additional research is necessary to demonstrate adequate comparison of the high flow nasal cannula to nasal CPAP units. B. Ventilator management—for severe CLD patients who require ventilatory support post extubation. • Nasal CPAP settings—initial settings 4 to 5 cm H2O. Adjust pressures in increments of 1 to 2 cm H2O to keep PaCO2 less than 50 mm Hg. FiO2 to keep saturations between 88% and 92%. There may be instances in which the PaCO2 will be allowed to be higher than 50 mm Hg (called permissive hypercapnia). • Mechanical ventilation—initial settings

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• Common modes available on new generation ventilators include SIMV, assist/control, pressure support ventilation (PSV), and volume guarantee (VG). The choice of mode will depend on the clinician’s experience and clinical judgment. • Ventilator frequency—adjusted to keep PaCO2 40 to 50 mm Hg; in CLD, PaCO2 may be higher than 50 mm Hg in an effort to protect the lungs from ventilator-associated injury. • Frequency of 40 to 50 breaths/min for infants • Frequency of 12 to 20 breaths/min for pediatric • Ventilator tidal volume—6 to 8 mL/kg for pediatric • Ventilator tidal volume—4 to 6 mL/kg for infants • Ventilator PEEP—5 to 8 cm H2O • Ventilator FiO2—to keep saturation greater than 92%; PaO2 between 50 and 70 mm Hg • Keep peak airway pressure (PAP) less than 25 cm H2O if able to maintain PaCO2 between 40 and 50 mm Hg • Goal is adequate chest rise. • Avoid overdistention of the lungs. • Ventilator inspiratory time—ranges from 0.3 sec to 1 sec depending on the size of the child and the results of the arterial blood gas. III. Pharmacology Strategy A. Short-acting bronchodilator—has been shown to help manage bronchospasms. Albuterol and levalbuterol (Xopenex) are the two most common short-acting bronchodilators. Both have been shown to be safe when used in both infants and children. These medications are available in a nebulizer or a metered dose inhaler. Metered dose inhalers are used most often in the treatment of CLD when patients are discharged from either the NICU or PICU. This is of particular importance because medications like fluticasone (Flovent) are often prescribed for ongoing use. Currently, budesonide (Pulmicort) has been prescribed more often for children with CLD, which can be given as a nebulized treatment or metered dose inhaled treatment. Treatment given

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as a metered dose inhaler should be given with a holding chamber for better deposition. B. Corticosteroids—Research indicates that steroids have demonstrated a decrease in the incidence of CLD; however, the American Academy of Pediatrics (AAP) has issued a recommendation that corticosteroids should not be used in preterm infants.15 Despite this warning, clinicians continue to use steroids in patients with severe lung injury and those considered ventilator dependent.16 Early research shows that dexamethasone8,9,17 has been used in the treatment of CLD despite the warning by the AAP. C. Nonsteroidal anti-inflammatory medications—Drugs such as cromolyn sodium and nedocromil sodium have demonstrated some benefits in preventing mast cell rupture; however, these medications are associated more often with children who have chronic asthma. D. Diuretics—Lasix has been well documented in the management of fluid-overload.8 In the long-term treatment of children with CLD, thiazide diuretics such as Aldactone have been shown to increase urine output and improve pulmonary functions.8 E. Antibiotics—It has been documented that during the first few years of life, CLD infants tend to have an increased number of respiratory infections, resulting in the need for good pulmonary toiletry and good hydration. Studies show that Ureaplasma urealyticum has been an indicator of CLD and promotes tissue inflammation and early stages of pulmonary fibrosis.8 F. Table 4-2 illustrates the more common medications used in the treatment of CLD. IV. Nutrition Strategy A. Nutritional support—The literature states that nutritional support improves CLD outcomes by reducing the need for supplemental oxygen and the ability to wean quickly from the ventilator. Children with CLD require an increase in caloric intake. A diet with adequate proteins, fats, carbohydrates, vitamins, and trace minerals helps prevent continued lung injury.8 According to William Driscoll and colleagues, several studies have shown that

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Table 4-2 Typical Dosages for Drugs Commonly Used in the Treatment of CLD Short-Acting Bronchodilators MDI Albuterol

Xopenex

Under 5 kg

Albuterol 1.25 mg

1–2 puffs

.31 mg

Over 5 kg

2.5 mg

1–2 puffs

.63 mg or 1.25 mg (weight dependent)

Anticholinergic Atrovent (ipratropium bromide) can be given as either nebulizer or MDI Nebulizer

MDI 18 mcg/puff

Under 5 kg

0.25 mg

2 puffs

Over 5 kg

0.50 mg

2 puffs

Diuretics—prescribed based on weight Lasix (furosemide) 0.5–2 mg/kg/dose PO or IV BID or QOD (QD in infants less than 31 weeks postconceptual age) Aldactone (Your unit most likely has established guidelines on the dose of this medication.) Antibiotics Tobramycin—it is recommended to be given after the short-acting bronchodilator to prevent bronchospasms. Under 5 kg

1 mL or 40 mg with nebulizer

Over 5 kg


Inhaled steroids Decadron (dexamethasone) 0.15–0.25 mg/kg/dose by mouth or IV divided BID; wean over 5–7 days.17 Pulmicort (budesonide)—given in a nebulizer—this medication should not be mixed with other medications in the nebulizer. Under 5 kg

0.25 mg ampule

Over 5 kg

0.50 mg ampule

Nonsteroidal anti-inflammatory Intal (cromolyn sodium) Under 5 kg


Over 5 kg


Note: This is not an all-inclusive list of the medications that are used for children with CLD. This list represents typical drugs that have been documented as having some benefits in treating the respiratory symptoms in CLD. It is recommended that you refer to a pharmacology book that describes pediatric and infant medications for an in-depth discussion of the various types of medications.

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a vitamin A supplement may speed up lung repair mechanism and thereby decrease the incidence of CLD.10 Summary

To summarize, this chapter covered the following facts about chronic lung disease of the newborn: ✔✔ It is a chronic respiratory disease that affects premature infants exposed to mechanical ventilation and oxygen therapy. ✔✔ It affects mainly premature infants who lack surfactant and/or who have very low birth weight. ✔✔ It results in impaired gas exchange, lung collapse, and inflammation. ✔✔ It is categorized in four stages based on infant’s age and severity. ✔✔ It requires a multidisciplinary team approach to manage this chronic condition. Although CLD is a very complex condition, a child with CLD can be managed well with the right type of therapy. Our expertise as respiratory therapists in the NICU and PICU can make a big difference in helping shape the long-term care plan of these children. Given that we interact with these patients from the delivery room to discharge, our role as experts in ventilator management and oxygen therapy can and should make a difference in the lives of children with CLD and their families. References 1. Baraldi, E., & Filippone, M. (2007). Chronic lung disease after premature birth. New England Journal of Medicine, 357 (19), 1946–1955. 2. National Institute of Child Health and Human Development/National Heart, Lung, and Blood Institute/Office of Rare Diseases. (2000, June 1–2). Workshop on bronchopulmonary dysplasia, Bethesda, MD. 3. Jobe, A., & Bancalari, E. (2001). Chronic lung disease of the newborn. American Journal of Respiratory and Critical Care Medicine, 163 (7), 1723–1729. 4. Ehrenkranz, R., Walsh, M., Vohr, B., Jobe, A., Wright, L., Fanaroff, A., et al. (2005, December). Validation of the National Institutes of Health consensus definition of chronic lung disease of the newborn. Pediatrics, 116 (6), 1353–1360. 5. Kacmarek, R., Dimas, S., Mack, C. (2005). The essentials of respiratory care (4th ed.). St. Louis, MO: Mosby Elsevier. 6. Walsh, M., Szefler, S., Davis, J., Allen, M., Van Marter, L., Abman, S., et al. (2006). Summary proceedings from the Bronchopulmonary Dysplasia Group. Pediatrics, 117, S52–S56. Retrieved February 22, 2008, from http://www.pediatrics. org/cgi/content/full/117/3/S1/S52

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7. National Asthma Education and Prevention Program (NAEPP). (2007). Expert panel report 3: Guidelines for the diagnosis and management of asthma. Bethesda, MD: National Institutes of Health (NIH Pub. No. 08-5846). Retrieved February 22, 2008, from http://www.nhlbi.nih.gov/guidelines/asthma/asthsumm.htm 8. Driscoll, W., & Davis, J. (2007, April 23). Chronic lung disease of the newborn. Retrieved July 13, 2008, from http:// www.emedicine.com/PED/topic 289.htm 9. Walsh, M., Yao, Q., Horbar, J., Carpenter, J., Lee, S., & Ohlsson, A. (2006). Changes in the use of postnatal steroids for chronic lung disease of the newborn in 3 large neonatal networks. Pediatrics, 118, e1328–e1335. Retrieved on June 7, 2008, from http://www.pediatrics.org/cgi/content/full/118/5/e1328 10. Saslow, J., Aghai, Z., Nakhla, T., Hart, J., Lawrysh, R., Stahl, G., et al. (2006). Work of breathing using high-flow nasal cannula in preterm infants. Journal of Perinatology, 26, 476–480. 11. Holleman-Duray, D., Kauris, D., & Weiss, M. (2007). Heated humidified high-flow nasal cannula: Use and a neonatal early extubation protocol. Journal of Perinatology, 27, 776–781. 12. Woodhead, D., Lambert, D., Clark, J., & Christensen, R. (2006). Comparing two methods of delivering high-flow gas therapy by nasal cannula following endotracheal extubation: A prospective, randomized, masked, crossover trial. Journal of Perinatology, 26, 481–485. 13. Spence, K., Murphy, D., Kilian, C., McGonigle, R., & Kilani, R. (2007). High-flow nasal cannula as a device to provide continuous positive airway pressure in infants. Journal of Perinatology, 27, 772–775. 14. Waugh, J., & Granger, W. (2004, August). An evaluation of 2 new devices for nasal high-flow gas therapy. Respiratory Care, 49 (8), 902–906. 15. Jobe, A. (2004, March). Postnatal corticosteroids for preterm infants—Do what we say, not what we do. New England Journal of Medicine, 350 (13), 1349–1351. Retrieved June 21, 2008, from http://content.nejm.org/cgi/content/ full/350/13/1349 16. Eichenwald, E., & and Stark, A. (2008, April). Management and outcomes of very low birth weight. New England Journal of Medicine, 358 (16), 1700–1711. Retrieved June 21, 2008, from http://content.nejm.org/cgi/content/full/358/16/1700 17. Shenai, J., Mellen, B., & Chytil, F. (2000). Vitamin A status and postnatal dexamethasone treatment in chronic lung disease of the newborn. Pediatrics, 106 (3), 547–553. Retrieved on June 7, 2008, from http://www.pediatrics.org/cgi/ content/full/106/3/547

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Chapter

5

Cystic Fibrosis Chapter Outline DEFINE • Define cystic fibrosis (CF) • Discuss who is affected by cystic fibrosis DESCRIBE • Describe the pulmonary clinical presentation of cystic fibrosis • Describe the nonpulmonary clinical presentation of cystic fibrosis DISTINGUISH • Distinguish cystic fibrosis from other conditions RESEARCH • Relevant research on cystic fibrosis

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TREATMENT • Treatment options in the care of cystic fibrosis patients • Respiratory therapist’s role in the management of cystic fibrosis patients

Key Terms Bronchodilator Chronic lung disease Chronic obstructive pulmonary disease Corticosteroids Cystic fibrosis Nebulizer therapy Oxygen therapy

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Chapter 5 Cystic Fibrosis

INTRODUCTION

Although this chapter contains an overall discussion of CF, the main points of this chapter will highlight children seen either on the general pediatric unit or those seen in the pediatric intensive care units. Historical Facts Dr. Dorothy Andersen’s landmark medical report identifying cystic fibrosis (CF) as a separate disease was published in 1938.1 Eighteen years later, in 1953, Dr. Paul di Sant’Agnese and his colleagues connected the loss of extra salt in patients with CF as the primary defect in cystic fibrosis.1,2 In 1955, the Cystic Fibrosis Foundation was created, and its primary mission is to spur growth in CF research that will lead to a possible cure. In 1962, the average survival age was 10 years; in 2005, the average survival age was nearly 37 years.2 CF centers of excellence have provided comprehensive care to patients with cystic fibrosis, and this has contributed significantly to the survival rate of patients afflicted by this condition.

DEFINE

Cystic fibrosis is an autoimmune hereditary genetic disorder located on chromosome 7. This gene has been known to have over 1500 mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene.1 According to Dr. Michael Knowles (2002), there are two types of cystic fibrosis: classic and nonclassic. Knowles points out that classic “reflects two loss-of-function mutations in the CFTR gene” and nonclassic has “partial function of the CFTR protein.”3 CF is a hereditary condition affecting the autonomic nervous system that causes an abnormal overproduction of secretions, which interferes with normal body function. This overproduction of secretions can lead to tissue and organ damage; this is especially true in the lungs and digestive tract. It is an autosomal hereditary condition, which means it can affect both male and female children. Who Is Affected by Cystic Fibrosis? It is documented that 30,000 people in the United States have CF, and more than 10 million Americans are carriers of the CF gene. Cystic fibrosis is most common among Caucasians, occurring in 1 in 3200 white births. It is less common in African Americans and Asians: 1 in 17,000

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and 1 in 25,500, respectively.4,5 Each year, at least 1000 new cases of CF are diagnosed in the United States, and 80% of these new cases are in children under 3.4,5 Both the American College of Obstetricians and Gynecologists and the Centers for Disease Control (CDC) recommend that all pregnant women be screened for the CF gene; however, in the United States only 20% of pregnant women are screened.4,5 By the year 2000, nearly 400,000 newborns were screened for cystic fibrosis.4 DESCRIBE

Cystic fibrosis transmembrane conductance regulator is the protein that is responsible for the regulation of salt and water in and out of the cells in the body. In the classic presentation of CF, the loss of the gene function to regulate salt and water causes a buildup of thick, sticky mucus, which leads to airway obstruction, bacterial infection, pancreatic insufficiency, and infertility in males. In the nonclassic presentation of CF, there are few if any signs of malabsorption. In this instance, much of the pancreatic exocrine function is preserved. The sweat chloride test is the standard in diagnosing cystic fibrosis. In classic CF, a sweat test value of 90 to 110 mmol per liter is conclusive of the diagnosis, whereas in nonclassic CF, a value of 60 to 90 mmol per liter is a high indicator.3 Because there are similarities between classic CF and nonclassic CF, Knowles et al. present a consensus statement to further define cystic fibrosis: “[Cystic fibrosis is] the presence of a coherent clinical syndrome, plus either evidence of CFTR dysfunction (an abnormal value for sweat chloride or nasal potential difference) or confirmation of cystic fibrosiscausing mutations on both alleles.”3 Food for Thought CF is generally suspected when a child presents in the emergency room with a persistent cough, thick sputum, signs of dehydration, and poor weight gain. Parents often describe a salty taste on the skin when they kiss their baby. The parents further describe normal eating habits but the inability to gain weight and more than usual amounts of coughs or respiratory infections. In clinical practice, these are typical signs of cystic fibrosis.

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Common signs and symptoms of CF include the following:* • • • • • • • •

Skin that tastes salty Increased mucus production with frequent coughing spells Frequent pulmonary infections leading to pneumonia and bronchitis Dehydration Infertility in men Diarrhea or bulky, foul-smelling, and greasy stools Poor weight gain and stunted growth in children Stomach pain secondary to obstruction of the liver, gallbladder, and/ or pancreas • Digital clubbing, hypoxemia, cyanosis, and dyspnea • Atelectasis • Pneumothorax Remember: Although these are common symptoms, not all CF patients will demonstrate all of these clinical manifestations. Recall that in nonclassic CF, patients may not demonstrate many of these clinical features. For example, the nonclassic CF patient may not have a problem with weight gain or evidence of diarrhea. DISTINGUISH

Cystic fibrosis is a condition that affects a number of bodily organs. It must be distinguished from other pulmonary and nonpulmonary illnesses that mimic cystic fibrosis, such as the following: • Bronchitis—chronic inflammation of the bronchus. Swollen bronchial tubes that are decreased in diameter and filled with mucus. • Bronchiectasis—chronic condition of the bronchial tubes or the large airway in which the airway or bronchial passages become enlarged and lose the ability to recoil back to their normal shape. This stretch is due to the collection of mucus in air sacs that is not removed by coughing. Mucus retention creates a moist environment for bacterial growth. • Sinusitis—chronic sinus infections that develop as a result of swollen sinuses that are blocked with mucus.

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• Pancreatitis—acute inflammation of the pancreas that causes severe abdominal pain. Although cystic fibrosis can lead to other medical conditions, often patients with CF have concurrent medical problems exacerbated by cystic fibrosis. Because CF is an overproduction of secretions, and because these secretions become thick due to low viscosity, the secretions have difficulty moving throughout the body and cause blockages of openings to many organs in the body, which results in subsequent damage to the organs. Care must be made to distinguish a diagnosis of cystic fibrosis from a non–cystic fibrosis condition. RESEARCH

Cystic fibrosis has an impressive history, beginning with its identification as a separate disease in 1938 by Dr. Andersen.2 Since this time, a number of milestones in CF research have been accomplished. The CF Foundation, one of the most active research foundations worldwide, is responsible for funding a majority of the research involving cystic fibrosis in the United States (http://www.cff.org/AboutCF/). Much of the research has revolved around treatment options for patients living with cystic fibrosis. From 1988 through 2007, there has been a proliferation of clinical trials aimed at bringing new drugs to the market that could treat the symptoms related to pulmonary infections.2 In 1994, the Federal Drug Administration (FDA) approved Pulmozyme—a medication designed to thin mucus in the lungs.2 CF patients suffer from numerous respiratory infections from various organisms. The most common is Pseudomonas aeruginosa (P. aeruginosa).6 P aeruginosa is a gram-negative, rod-shaped bacteria that occurs regularly on the surface of plants. It can also occur on the surface of animals. P aeruginosa is the most common opportunistic pathogen of humans affecting the respiratory system of immunosuppressed patients, and is considered a common hospital-acquired infection.7 Much of the research has been devoted to determining whether oral antipseudomonal antibiotics are beneficial to the CF patient in helping rid the body of P aeruginosa. Ryan et al. concluded that from the clinical trials they reviewed, nebulized antipseudomonal antibiotics

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have demonstrated improvement in lung function with fewer trips to the hospital and fewer respiratory exacerbations that are common among CF patients. The clinical trials reviewed by Wood and Smyth saw evidence of the benefits of antibiotic treatment in the short-term relief of P. aeruginosa; however, they could not determine whether short-term gains from the use of antibiotics would benefit the CF patient.8 Elkins et al. researched the use of inhaled hypertonic saline and its effects on mucociliary clearance. Their research demonstrated that inhaled hypertonic saline increased mucus clearance, was inexpensive, and was safe to use in patients with CF.9 Another study, by Scott Donaldson and his colleagues, concurs with the findings of Elkins et al. in that hypertonic saline solution is an effective solution to sustain mucus clearance.10 Although there is a lot of research on drug therapy, there are other modalities that would benefit CF patients. Bronchopulmonary hygiene is a mechanism used to clear the airway to prevent bacterial infections that often lead to acute exacerbations of CF symptoms.11 More than 40 years ago, manual chest physiotherapy (CPT) was the gold standard in the treatment of patients with CF. Currently there are improved techniques in the management of CF aimed at improving pulmonary function. In the treatment section of this book, many of these modalities will be described in detail. Respiratory therapists concentrate on keeping the lungs clear; however, proper nutrition is also a key component to successful treatment. The inability to absorb adequate calories will significantly impact weight gain and overall lung health. Nutritional support should not be minimized. Elissa Jelalian et al. suggest that nutritional status and malnutrition strongly correlate with the patient’s pulmonary health status.12 Jelalian et al. further suggest that the relationship between good nutrition and good health is gaining recognition. Another interesting study, done by Scott Powers et al., suggests that behavioral factors play a significant role in weight gain among toddlers and preschoolers with cystic fibrosis.13 Powers et al. concluded that negative behavioral reinforcements have been associated with negative weight gain. Although CF research is ongoing, there are a number of patients who are in the end-stage period of their pulmonary condition, in which

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medical therapies have failed and the patients may qualify for lung transplantation. According to Theodore Liou et al. of the University of Utah, “Lung transplantation is the most aggressive therapy for end-stage lung disease in cystic fibrosis.”14 Liou also reports that 80% of CF patients succumb to end-stage lung disease each year. The heart-lung transplant was the first such procedure; however, it has been supplanted by the bilateral sequential lung transplant.14 The first lung transplant on a CF patient was performed in 1983 by a team at the University of Pittsburgh.14 Since that time, the technique for lung transplantation has been refined, resulting in better surgical outcomes and longevity for the CF patient. Although there is reported success with lung transplantation, the main limitation to this procedure is the limited number of available organs. Most organ transplants are received from living organ donors; however, there is active research in the United States to consider the use of organs from donors after cardiac death.14 It is believed that using organs from donors who have succumbed to cardiac death may increase the availability of organs. TREATMENT

The cystic fibrosis treatment plan requires a multidisciplinary team approach, which may include medicine, nursing, respiratory therapy, nutrition, pharmacy, and social work. Each member works in tandem with the family to develop a comprehensive plan aimed at managing the longterm effects of CF. This section highlights the treatment options commonly used for CF patients. (Table 5-1 illustrates some of the various devices or therapies found under each of these options.) A comprehensive plan would include many of these therapies: • Respiratory therapy—There are a number of bronchopulmonary hygiene therapies designed to slow the effects of deteriorating lung functions. Manual CPT was the gold standard in the care of CF patients until early in the 21st century. In the last 5 years, researchers have measured the effect that CPT has on slowing the deterioration of lung function.15,16,17,18 Christopher Oermann et al. report that

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Table 5-1 Respiratory Treatment Nonpharmacological Options Treatment Option

Applications

Respiratory

Manual chest physiotherapy (CPT) Manual clapping or percussing of the chest wall with postural drainage, followed by inspiratory vibration. This therapy is done at least twice per day for as long as 30 to 45 minutes per session. Forced coughing follows CPT during and after each session. (See Chapter 10, pages 231–233, for illustrations of the various positions used to provide manual CPT.) High-frequency chest wall oscillation (chest vest) Application of a vest around the chest wall connected to an air pulsating generator that applies high frequency to the chest wall. Figure 5-1 illustrates a chest vest and the generator. Vibratory devices Flutter valve uses a metal ball into which you blow. The back pressure is transmitted to the chest wall, causing vibration. Figure 5-2 illustrates the flutter valve. PEP therapy is administered with a face mask from 5 to 20 cm H20 for a period of 15 to 30 minutes. This helps to either increase gas pressure behind secretion or prevent airway collapse.11 Figure 5-3 illustrates PEP therapy. Acapella uses a spring device in which you control the level of difficulty. The patient uses a mouthpiece to blow into the device, and it causes back pressure to be transmitted to the chest wall, causing a vibration to the airway. Figure 5-4 illustrates the Acapella. IPV-1 is used most often with children who have neuromuscular weakness to promote coughing. It has limited use in CF patients. IPV uses a small burst of air at 200 to 300 cycles per minute, while delivering aerosol medications to the airway. Figure 5-5 illustrates the IPV.

although manual CPT has been proven to be effective, there is poor compliance because patients report dissatisfaction with manual CPT. Oermann and his group further state that although newer therapies are available, the positive expiratory pressure (PEP) is the only modality that has been studied extensively. The other devices, such as the flutter and chest vest, have not been validated for the efficacy.15 McCool and Rosen of Memorial Hospital of Rhode Island recommend PEP therapy over manual CPT and indicate that PEP therapy has been found to be as effective as conventional CPT, and even though these newer devices have not been thoroughly tested for efficacy, patient satisfaction is quite high for the use of these alternate devices compared to manual CPT.16 The American College of Chest Physicians

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Figure 5-1 High-frequency chest wall oscillatory vest The Vest® Airway Clearance System is a registered trademark of Hill-Rom Services, Inc. © 2009 Hill-Rom Services, Inc. REPRINTED WITH PERMISSION-ALL RIGHTS RESERVED

Content removed due to copyright restrictions

Figure 5-2 Flutter Valve

Figure 5-3 PEP therapy

111

112


Figure 5-4 Acapella Valve

Figure 5-5 IPV

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made recommendations regarding the use of airway clearance devices. Table 5-2 highlights some of their recommendations. Vibratory devices such as the flutter valve, Acapella, intrapulmonary percussive ventilation (IPV), and high-frequency chest wall oscillation (chest vest) are options for self-administration of CPT. Each device causes a vibration action on the chest wall. For example, the high-frequency chest wall oscillation uses an inflatable vest to deliver very fast vibrations to the chest wall. A study done by Stites et al. at the University of Kansas Medical Center demonstrated that the chest vest allows for self-administration, lessens the need for caregivers to provide therapy, and is as effective as manual CPT.17 Stites and his group were actually studying the effects of aerosol deposition using the chest vest.16 Each of these devices has its advantages and disadvantages. Not much research has been done on some of the newer devices, yet these therapies have become common practice in the management of CF patients. Robert Kempainen and his group initiated a clinical Table 5-2 ACCP Recommendations for Airway Clearance Therapies The American College of Chest Physicians makes the following recommendations with regard to the use of airway clearance devices:11 1. In patients with CF, chest physiotherapy is recommended as an effective technique to increase mucus clearance, but the effects of each treatment are relatively modest and the long-term benefits unproven. 2. In patients with COPD and CF, huffing should be taught as an adjunct to other methods of sputum clearance. 3. In patients with CF, autogenic drainage should be taught as an adjunct to postural drainage as a method to clear sputum because it has the advantage of being performed without assistance and in one position. 4. In patients with CF, PEP is recommended over conventional chest physiotherapy because it is approximately as effective as chest physiotherapy and is inexpensive, safe, and can be self-administered. 5. In patients with CF, devices designed to oscillate gas in the airway, either directly or by compressing the chest wall, can be considered alternative to chest physiotherapy. 6. The effect of nonpharmacologic airway clearance techniques on long-term outcomes such as health-related quality of life and rates of exacerbations, hospitalizations, and mortality is not known at this time. The committee recommends that future investigations measure these outcomes in patients with CF, and in other populations with bronchiectasis, COPD, and neuromuscular diseases. Adapted from: McCool, F. D., & Rosen, M. J. (2006). Nonpharmacologic airway clearance therapies: ACCP evidence-based clinical practice. Chest, 129, 250–259.

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•

•

• • •


trial comparing the chest vest with differing waveforms for airway clearance. They found that the chest vest demonstrated only moderate changes in sputum production. The group suggested that patients favored the chest vest because it allowed them more independence.19 Chest physiotherapy • Manual percussion, postural drainage, and vibrations • High-frequency chest wall oscillation (chest vest therapy) • Positive expiratory therapy (PEP therapy) • Flutter valve therapy • Acapella therapy • Intrapulmonary percussive ventilation (IPV) Medications (see also Table 5-3) • Bronchodilators • Mucolytics • Antibiotics • Anti-inflammatory Nutritional support • Vitamin supplementation • Whole protein supplementation Pancreatic enzyme replacement therapy • Enzyme supplementation Surgical options

Table 5-3 Respiratory Treatment Pharmacological Options Medication

Route of Administration

Dosage

Onset of Action

Duration of Action

Albuterol—short-acting bronchodilator-Beta2 agonist

Nebulizer Pediatric dose MDI (90 mcg/puff)

2.5–5 mg Q4–6 hr 0.63 mg or 1.25 mg 1–3 puffs Q4–6 hr

Within 5 min Within 5 min Within 5 min

4 to 6 hours 4 to 6 hours 4 to 6 hours

Xopenex—short-acting bronchodilator-Beta2 agonist

Nebulizer

0.63–1.25 mg Within 5–10 min Q4–8 hr

Bronchodilator Therapy

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4 to 8 hours

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Table 5-3 Respiratory Treatment Pharmacological Options (Continues) Medication


Dosage

Onset of Action

Duration of Action

Atrovent—anticholinergic

Nebulizer MDI (18 mcg/puff)

0.5 mg Q6 or QID 2 puffs Q6 or QID

Within 20 min Within 20 min

4 to 8 hours 4 to 8 hours

Spiriva

DPI (18 mcg/capsule)

1 DPI capsule QDay

Within 20 min

24 hours

Duoneb Albuterol and Atrovent

Nebulizer

Within 5 min Within 20 min


2 puffs Q6 or QID Max of 12 puffs daily

Albuterol 5 min Atrovent 20 min


Serevent Flovent

10–20 min varies

12 hours varies

Combivent Albuterol and Atrovent

Advair—long-acting bronchodilator-Beta2 agonist with inhaled corticosteroid Serevent and Flovent Advair should not be used to relieve acute bronchospasm.

MDI (90 mcg/puff albuterol and 18 mcg/puff Atrovent) DPI—available in Flovent/Serevent 100/50 mcg 250/50 mcg 500/50 mcg

1 vial contains 2.5 mg Albuterol and 0.5 mg Atrovent Q6 hours or QID

Mucolytics Mucomyst

Nebulizer

3 ml of either 10% or 20% strength TID or QID

Currently not recommended for use as mucolytic agent19

N/A

Pulmozyme

Nebulizer

2.5 mg QDay

N/A

N/A (continues)

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Table 5-3 Respiratory Treatment Pharmacological Options (Continued) Medication


Dosage

Onset of Action

Duration of Action

Hypertonic Saline

Nebulizer

4 ml of 7%20

Research recommends administering a prebronchodilator 20

N/A

Antibiotic Therapy or Anti-Infective Medications Tobramycin (TOBI)

Nebulizer

300 mg BID every other 28 days

N/A

N/A

Pentamidine

Specialized nebulizer

300 mg once

N/A

N/A

N/A N/A

N/A N/A

N/A

N/A

every 28 days Corticosteroid Anti-Inflammatory Drugs Budesonide

DPI (200 mg)—children older than 6 Nebulizer—12 months to 8 years

Beclomethasone (QVAR)

MDI 40 μg puff 80 μg puff

1 puff BID 0.5 mg either QDay or BID 1 or 2 puffs BID 1 or 2 puffs BID

Aerobid

MDI 250 mg puff

2 puffs BID

N/A

N/A

Flovent

MDI 44 mg or 110 mg DPI 50 mg or 100 mg

2 puffs BID 2 puffs BID

N/A N/A

N/A N/A

1 or 2 puffs TID or QID

N/A

N/A

Azmacort

MDI 250 mg

Note: This represents some of the medications used in the treatment of patients with CF. It is recommended that the reader refer to a pharmacological book that lists all available drugs with dosage, route of administration, onset action, and time of duration.21

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Summary

To summarize, in this chapter we covered the basics on cystic fibrosis: ✔✔ It is an autoimmune recessive hereditary gene disorder characterized by an overproduction of abnormal secretions that interfere with normal body function. ✔✔ It affects white children more often than nonwhite children. ✔✔ It is autosomal. ✔✔ It affects many organs in the body, particularly those in the pulmonary system. ✔✔ It is categorized as either classic CF or nonclassic CF; classic is the more severe form of the disease. ✔✔ It requires a multidisciplinary team approach to manage this chronic condition. Although CF is a very complex condition, a child with CF can be managed well with the right type of therapy. It has been shown that patients with CF are living longer and enjoying better quality of life. This longevity has been attributed to the proliferation of research studies that have enabled the development of better drugs and therapies to slow the decline of the respiratory system. References 1. Mogayzel, P. (2007, December). Aggressive Treatment Strategies in the Fight Against cystic fibrosis. Johns Hopkins University Faulty Monograph Series, 7 (14). Retrieved February 20, 2008, from http://www.jhasim.com/template.cfm 2. Cystic Fibrosis Foundations. (n.d.). Research milestones. Retrieved November 30, 2007, from http://www.cff.org/ AboutCF/ 3. Knowles, M., & Durie, P. (2002, August). What is cystic fibrosis? New England Journal of Medicine, 347 (6), 439–442. 4. American Lung Association. (2006, November). Cystic fibrosis fact sheet: Diseases A–Z. Retrieved February 20, 2008, from http://www.lungusa.org/site/apps/nlnet/content3 5. National Heart Lung and Blood Institute. (n.d.). Diseases and conditions index: Cystic fibrosis fact sheet. Retrieved November 30, 2007, from http://nhlbi.nih.gov/health/dci/Diseases/cf/cf_what.html 6. Ryan, G., Mukhopadhyay, S., & Singh, M. (2000). Nebulised anti-pseudomonal antibiotics for cystic fibrosis. Cochrane Database System Review, (2), CD001021. 7. Todar, K. (2008). Todar’s online textbook of bacteriology. Retrieved July 4, 2009, from http://www. textbookofbacteriology.net/pseudomonas.html 8. Wood, D., & Smith, A. (2006, January 25). Antibiotic strategies for eradicating Pseudomonas aeruginosa in people with cystic fibrosis. Cochrane Database System Review, (1), CD004197.

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9. Elkins, M., Robinson, M., Rose, B., Harbour, C., Moriarty, C., Marks, et al. for the National Hypertonic Saline in Cystic Fibrosis (NHSCF) Study Group. (2006, January). A controlled trial of long-term inhaled hypertonic saline in patients with cystic fibrosis. New England Journal of Medicine, 354 (3), 229–240. 10. Donaldson, S., Bennett, W., Kirby, Z., Knowles, M., Tarran, R., & Boucher, R. (2006, January). Mucus clearance and lung function in cystic fibrosis with hypertonic saline. New England Journal of Medicine, 354 (3), 241–250. 11. Smyth, R. (2005). Diagnosis and management of cystic fibrosis. Archive Disease Childhood Education & Practice, 90, 1–6. Retrieved February 29, 2008, from http://ep-bmj.com/cgi/content/full/90/1/ep1 12. Jelalian, E., Stark, L., Reynolds, L., & Seifer, R. (1998, March). Nutrition intervention for weight gain in cystic fibrosis: A meta analysis. Journal of Pediatrics, 132 (3), 486–492. 13. Powers, S., Jones, J., Ferguson, K., Piazza-Waggoner, C., Daines, C., & Acton, J. (2005, December). Randomized clinical trial of behavioral and nutrition treatment to improve energy intake and growth in toddlers and preschoolers with cystic fibrosis. Pediatrics, 116 (6), 1442–1450. 14. Liou, T., Woo, M., & Cahill, B. (2006). Lung transplantation for cystic fibrosis. Current Opinion Pulmonary Medicine, 12, 459–463. 15. Oermann, C., Swank, P., & Sockrider, M. (2000). Validation of an instrument measuring patient satisfaction with chest physiotherapy techniques in cystic fibrosis. Chest, 118, 92–97. Retrieved February 26, 2008, from http://www. chestjournal.org/cgi/content/abstract/118/1/92 16. McCool, F., & Rosen, M. (2006). Nonpharmacologic airway clearance therapies: ACCP evidence-based clinical practice guidelines. Chest, 129, 250–259. Retrieved February 26, 2008, from http://www.chestjournal.org/cgi/content/ abstract/129/1_suppl/250S 17. Stites, S., Perry, G., Peddicord, T., Cox, G., McMillan, C., & Becker, B. (2006). Effect of high-frequency chest wall oscillation on the central and peripheral distribution of aerosolized diethylene triamine penta-acetic acid as compared to standard chest physiotherapy in cystic fibrosis. Chest, 129, 712–717. Retrieved February 26, 2008, from http://www. chestjournal.org/cgi/content/abstract/129/3/712 18. McCarren, B., & Alison, J. (2006). Physiological effects of vibration in subjects with cystic fibrosis. European Respiratory Journal, 27 (6), 1204–1209. 19. Kempainen, R., Williams, C., Hazelwood, A., Rubin, B., & Milla, C. (2007). Comparison of high-frequency chest wall oscillation with differing waveforms for airway clearance in cystic fibrosis. Chest, 132 (4), 1227–1232. 20. Cystic Fibrosis Foundations. (n.d.). Hypertonic saline therapy for CF: Is it right for you? Retrieved August 17, 2008, from http://www.cff.org/treatments/Therapies/Respiratory/HypertonicSaline/ 21. Gardenhire, D. (2008). Rau’s respiratory care pharmacology (7th ed.). St. Louis, MO: Mosby Elsevier.

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Chapter

6

Upper Airway Inflammatory Diseases Chapter Outline DEFINE • Define croup • Define epiglottitis DESCRIBE • Describe the clinical presentation of croup • Describe the clinical presentation of epiglottitis DISTINGUISH • Foreign body obstruction (FBO) • Bronchiolitis RESEARCH • Relevant research on croup and epiglottitis TREATMENT • Treatment options for patients with croup • Treatment options for patients with epiglottitis • Respiratory therapist role in the management of patients with airway inflammatory diseases

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Key Terms Budesonide (pulmicort) Cool mist tent Corticosteroids Croup Dexamethasone Epiglottitis Haemophilus influenzae type B vaccine Laryngeal edema Nebulized racemic epinephrine Respiratory syncytial virus (RSV)

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Chapter 6 Upper Airway Inflammatory Diseases

INTRODUCTION

Respiratory therapists working the emergency room during the winter are likely to hear a barky cough in between attempts to cry from young children. This barky cough is the most recognizable symptom of croup. November through March is croup season, and many children arrive in the emergency room needing medical attention. A barky cough is a clear indication of croup; however, it is necessary to distinguish between croup and epiglottitis. This chapter will define and compare each condition and discuss the role that respiratory therapists play in the treatment phase of each condition. DEFINE

Croup, also called laryngotracheitis, is viral condition that affects the subglottic tissue causing it to swell and obstruct the airway. Most often it is caused by the parainfluenza virus. According to Dr. James Cherry, (2008) croup is an illness that occurs in children under 6 years of age.1 It is more prevalent in boys and occurs most often between 7 months and 36 months of age.1 Table 6-1 illustrates the difference between croup and epiglottitis. Croup is either spasmodic croup or acute laryngotracheitis. Epiglottitis is a bacterial infection that causes the swelling of the supraglottic structures of the airway. The epiglottis is enlarged and has a cherry red coloration. In the majority of cases, epiglottitis is caused by Haemophilus influenzae type B. Epiglottitis can cause partial or complete blockage of the airway. Kent Whitaker, in his neonatal/pediatric book, describes epiglottitis as the inflammation of the epiglottis, vocal cords, the base of the tongue, and the aryepiglottic folds.2 Since the introduction of the Haemophilus influenzae type B vaccine, there have been very few cases of epiglottitis in children. Epiglottitis does occur in adults, but not necessarily due to Haemophilus influenzae type B: it is caused by other organisms found in older children or young adults who may not have received the Haemophilus influenzae vaccine. DESCRIBE

Historically, croup or croup-like illnesses were believed to be diphtheria.1 In modern medicine, viral croup is described as either laryngotracheitis

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Table 6-1 Highlights of the Differences Between Croup and Epiglottitis Epiglottitis

Croup

Age

3 to 6 years

6 months to 3 years

Rate of onset

Rapid, often within hours

Slow (2 to 3 days)

Infectious origin

Haemophilus influenzae type B

Parainfluenza virus or mycoplasma pneumoniae and respiratory syncytial virus

Clinical presentation

High fever, anxious leaning forward, drooling, low-pitch stridor, muffled voice, retractions and nasal flaring, sitting in a tripod position, and no barky cough.

May be afebrile or febrile. Hoarse barky cough, tight upper airway inspiratory stridor, runny nose, and retractions.

Chest radiograph

Swollen, edematous epiglottis (thumb sign, see Figure 6-1), and supraglottic structures seen on lateral neck film

Narrowing of the subglottic airway (hourglass or steeple sign, see Figure 6-2) seen on anterior-posterior (A-P) neck film

Occurrence

Any season

Usually winter

or spasmodic croup, characterized by the swelling of the lateral walls of the trachea below the vocal cords.1 Spasmodic croup typically occurs at night with no evidence of fever or inflammation. Acute laryngotracheitis is a more serious illness with evidence of inflammation of the larynx and tracheal and a low-grade fever. On the other hand, bacterial croup, more precisely known as laryngotracheobronchitis (LTB) or laryngotracheobronchopneumonitis (LTBP), is characterized by inflammatory cells in the tracheal wall.1 Both LTB and LTBP are described as inflammation of the larynx, trachea, and bronchi. Both conditions can lead to airway obstruction. Common symptoms of croup include inspiratory stridor, barking cough, hoarseness, retractions, use of accessory muscles, and low-grade fever. Epiglottitis is described as an inflammation of the soft tissue surrounding the epiglottis, which causes a blockage of the trachea, thus prevents breathing. This condition appears within 4 to 12 hours and is accompanied by high fever and muffled voice (see Table 6-1 for comparison of croup and epiglottitis). Patients with epiglottitis do not have the characteristic barky cough seen with croup, and this condition is not limited to seasonal occurrence. Common symptoms of epiglottitis include drooling, absence of a cough, sitting in a “tripod” position, inspiratory

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Figure 6-1 Thumb sign seen in epiglottis

stridor, and high fever. On chest x-rays, epiglottitis looks like a thumbsign (see Figure 6-1). DISTINGUISH

Although croup and epiglottitis are the main culprits of upper airway inflammatory conditions, care must be made to distinguish croup and epiglottitis from the following diagnoses: • Foreign-body airway obstruction (FBAO)—blockage of the airway caused by any innate item small enough to be swallowed. Foreignbody airway obstruction usually occurs suddenly, with no fever or other signs of infection.1 Lateral neck films may not be helpful in identifying the location of the object because most objects cannot be seen on chest x-rays. FBAO occurs more often in children from 7 months to 4 years and is the leading cause of death in children under 6 years.3 Common symptoms of FBAO are choking, retractions, struggling to breathe, gasping for air, and absent breath sounds.

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• Bronchiolitis—an inflammatory disease of the bronchioles caused by respiratory syncytial virus (RSV) or parainfluenza viruses. It is the most common cause of lower respiratory tract infections in children under 2 years.3 It occurs in the fall and winter and is highly contagious. Common symptoms of bronchiolitis are cough, increased respiratory rate, low-grade fever, retractions, wheezing, and cyanosis. RESEARCH

Kristine Rittichier et al. describe croup as an upper airway obstruction produced by subglottic edema.1 Croup is caused by a viral organism, the most common of which are parainfluenza types I and III and respiratory syncytial virus (RSV). The symptoms appear within 1 to 2 days after the presentation of the seal-like barky cough. Figure 6-2 shows a “steeple sign” representing a narrowing of the airway—a classic sign of croup. Most symptoms usually resolve over a period of 7 to 10 days. Perri Klass, MD, reports in the New England Journal of Medicine that when she hears the classic signs of croup over the telephone, she makes the following recommendations: “Children with respiratory distress go to the emergency room, and other children into a steamy bathroom to see whether the moisture helps.”4 Dr. Klass’s discussion of croup affirms our understanding in that croup is self-limiting, usually mild, and will resolve within 1 to 2 days. In moderate and severe cases, research shows that cool mist does little if any to resolve the symptoms,5 although the use of cool mist continues, particularly in mild croup. The treatment section will discuss how cool mist is administered for differing age groups. Steroid therapy is an area that researchers have focused on.6,7,8,9 For example, during the past 15 years, corticosteroids have been the treatment of choice to manage croup. The debate among clinicians is whether to give every symptomatic child steroids. Dr. Klass reports that not every child will need corticosteroids to manage his or her symptoms. However, if a physician believes that administering corticosteroids will shorten the length of the illness, ultimately speeding recovery, then he or she is likely to give rather than withhold. For moderate to severe symptoms of croup, research supports using steroids with the intent to decrease inflammation around the subglottic tissue, which will decrease the symptoms of

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Figure 6-2 Steeple sign or hourglass sign seen in croup

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moderate to severe croup. Dr. David Johnson et al. compared nebulized budesonide to intramuscular dexamethasone.7 The results showed that both budesonide (Pulmicort) and dexamethasone (Decadron) offered significant clinical improvement, with dexamethasone providing the greatest improvement.7 It is well documented that using steroids reduces the need for hospitalization. A review of three studies done by Dr. Geelhoed and his colleagues published in the British Medical Journal compared nebulized budesonide to oral dexamethasone.8,9 They found that nebulized budesonide and oral dexamethasone were significantly better than placebo in reducing hospital stay and reducing croup scores; however, they also found that oral dexamethasone was preferred over nebulized budesonide.8,9 Children who present with severe symptoms of croup are likely to be treated with nebulized racemic epinephrine (microNefrin or Vaponefrin). Racemic epinephrine, an alpha 1 adrenergic agent, causes vasoconstriction that is critical in decreasing the inflammation in patients who have been diagnosed with severe croup. Patients who receive this treatment are likely to be admitted to the hospital for a minimum of 24 hours. This is due in part to the risk of rebound edema, typically seen 30 to 90 minutes after racemic epinephrine is given.10 Racemic epinephrine helps smooth out the bronchial walls and reduces edema and swelling. Nebulized racemic epinephrine is given every 1 to 2 hours, with close monitoring to watch for signs and symptoms of impending respiratory failure. Historical Facts An interesting fact about epiglottitis was found in the monologue “Death of a President.” It was December 1799 and the first U.S. president, George Washington, was “preparing to die.” Three physicians waited at his bedside trying to determine how to save him, as he lay struggling to breathe.11 It was difficult to know at the time how to diagnose epiglottitis because it had not been defined in the medical literature. It was after Washington’s death that epiglottitis, known then as cynanche trachealis, which means “dog strangulation,” was determined to be the malady that killed George Washington. Elisha Cullen Dick, a physician at Washington’s death, identified epiglottitis as “inflammation of the glottis, larynx, or upper part of the trachea … a rare occurrence … [producing] such an obstruction of the passage of air, as suffocates, and thereby proves suddenly fatal.”11

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Although epiglottitis is less common than croup, it has not been totally eradicated in modern medicine. Since the introduction of the Haemophilus influenzae type B vaccine, epiglottitis is less common in young children, yet there are still cases of epiglottitis in older children and young adults. Epiglottitis is not as prevalent as it once was; however, two cases of pediatric acute epiglottitis are described in the literature by Low et al. at the National University Hospital in Singapore from 1992 to 2001.12 Both children were treated for epiglottitis and provided with the Haemophilus influenzae type B vaccine. Low et al. stated that acute epiglottitis is rare in Singapore, yet when it occurs it can be life-threatening. They further pointed out that because epiglottitis is less common, medical clinicians must remain abreast of the seriousness of this condition. TREATMENT

Supportive therapy has been shown to be an effective means of treating patients with croup. Most parents are quite anxious when having to care for a child with croup. Keeping a parent informed of their child’s condition lessens their anxiety. Therapeutics used to treat croup include cool mist, oxygen therapy, pharmacology therapy, and positive pressure ventilation in very severe cases of croup. Table 6-2 illustrates the various treatment options available for patients with croup. One or more therapeutics may be used in the treatment of children with croup. Treatment options for croup are as follows: 1. Humidity therapy—Cool mist through a face mask or as blow-by

to the face is recommended only in mild cases of croup. The use of mist tent is no longer recommended. 2. Corticosteroids—Nebulized budesonide (Pulmicort) has shown effectiveness in managing croup. The nebulized dose reported in the research study from Dr. Geelhoed was 2 mg,8 which is four times the typical dose of 0.5 mg Pulmicort commonly used on the general pediatric units. Dexamethasone (Decadron) can be given in nebulized form; however, it is usually given either orally or intramuscular. Most research shows that 0.6 mg/kg of Decadron is administered to manage symptoms of croup.

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Table 6-2 Treatment Options for Croup and Epiglottitis Type of Therapy

Croup

Epiglottitis

Humidity therapy

Cool aerosol mist Face mask Blow-by Oxygen therapy may be required. Figure 6-3 shows a mist tent used for cool mist. Figure 6-4A-B shows a blow-by for the administration of cool mist with and without a mask.

Cool aerosol mist Blow-by Oxygen therapy may be required.

Medication

Nebulized Pulmicort In the emergency room 2 mg as ordered On the general pediatric unit 0.5 mg BID Nebulized racemic epinephrine In the emergency room and general pediatric unit 0.05 ml of 2.25% solution Intravenous or intramuscular corticosteroids 0.6 mg per kg of dexamethasone

Nebulized racemic epinephrine In the emergency room and general pediatric unit 0.05 ml of 2.25% solution following extubation if necessary Antibiotic therapy Ceftriaxone 80 mg per kg per day

Positive pressure ventilation

In mild cases, not likely. In severe cases with evidence of pending respiratory failure, intubation and mechanical ventilation may be necessary.

In severe case with evidence of pending respiratory failure, intubation and mechanical ventilation may be necessary. Intubation should be done in the operating room with a skilled anesthesiologist. Tracheostomy may be necessary.

Figure 6-3 Mist tent with cool mist

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A

B Figure 6-4 Cool mist (A) with a mask and (B) without a mask

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3. Racemic epinephrine (microNefrin or Vaponefrin)—This is given in

nebulized form. Typical dose is 0.05 ml of 2.25% solution. It can be given as often as every 2 hours as needed. Children who receive racemic epinephrine are monitored for a longer period of time before being discharged to home or admitted to the hospital for overnight observation. 4. Positive pressure ventilation—It has been reported that 3% to 6% of children with croup require intubation.3 Severe croup that progresses to respiratory failure, as evidenced by an acute rise in PaCO2 greater than 50, a decreased pH less than 7.25, and decreased PaO2 less than 60 on more than 50% of oxygen, will need to be intubated. Treatment options for epiglottitis are as follows: 1. Keep the child calm. It is better for the child to remain with the

parents to lessen the anxiety.

2. Provide cool mist as blow-by. Cool mist with oxygen therapy may

3.

4.

5. 6. 7. 8.

be required. The one benefit to cool mist is that it helps to liquefy the mucus, which may prevent mucus plugging. Prepare for intubation and resuscitation. It is best to take a child to the operating room where a tracheostomy or cricothyroidotomy can be performed, if necessary. Prepare to ventilate with a mechanical ventilator in case the child requires intubation. If positive pressure ventilation is required, ventilate with the least amount of positive pressure. Obtain sputum and blood cultures. Provide required antibiotic therapy. Determine weaning readiness. Ensure there is an audible leak around the endotracheal tube. Monitor closely following extubation. Nebulized racemic epinephrine may be needed following extubation.

Summary

This chapter compared croup and epiglottitis—conditions that affect the upper airway, causing narrowing and the potential for complete blockage of the airway. Even though there are similarities, there are many more

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differences between the two. It is those differences that prompt clinicians to be particularly careful in rendering the correct diagnosis. Each condition requires quick action. Children with epiglottitis tend to exhibit worsening respiratory symptoms and require immediate relief, should severe airway obstruction ensue. Children with mild croup are not usually admitted to the hospital, although they tend to come to the emergency room more often. Croup tends to be seasonal, whereas epiglottitis is yearround. The role of the respiratory therapist becomes more evident when either condition worsens to the point of respiratory failure. This is made clearer when mechanical ventilation is required. Croup ✔✔ Croup is an airway inflammatory condition that can be categorized as mild, moderate, or severe. It can be caused by any number of viral organisms. ✔✔ It is the swelling of subglottic tissue causing airway obstruction. ✔✔ It is characterized with a seal-like barky cough. ✔✔ Symptoms get worse at night. ✔✔ Severe cases of croup are typically treated on the inpatient unit of the hospital. Epiglottitis ✔✔ Epiglottitis is swelling of the soft tissue surrounding the subglottic structure. ✔✔ It is characterized by its rapid onset and high-grade fever. ✔✔ It has no distinctive cough, and often the patient will sit in the characteristic tripod position. ✔✔ Epiglottitis cause complete blockage of the airway. ✔✔ This condition is considered a medical emergency. Although croup and epiglottitis have many similarities, they remain two very distinct conditions that require medical management unique to its symptoms. Respiratory therapists are quite familiar with the symptoms of croup because this condition is more prevalent. Epiglottitis is less common than croup since the introduction of the Haemophilus influenzae type

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B vaccine. Epiglottitis has not been terminally eradicated, but the incidence of epiglottitis in recent years of pediatric care is extremely low. References 1. Cherry, J. (2008). Croup. New England Journal of Medicine, 358, 384–391. 2. Whitaker, K. (2001). Comprehensive perinatal and pediatric respiratory care (3rd ed.). Albany, NY: Delmar Thomson. 3. Kacmarek, R., Dimas, S., & Mack, C. (2005). The essentials of respiratory care (4th ed.). St. Louis, MO: Mosby Elsevier. 4. Klass, P. (2004). Croup—The bark is worse than the bite. New England Journal of Medicine, 351, 1283–1284. 5. Scolnik, D., Coates, A., Stephens, D., Da Silva, Z., Lavine, E., & Schuh, S. (2006). Controlled delivery of high vs low humidity vs mist therapy for croup in emergency departments: A randomized controlled trial. Journal of the American Medical Association, 295, 1274–1280. 6. Rittichier, K., & Ledwith, C. (2000, December). Outpatient treatment of moderate croup with dexamethasone intramuscular versus oral dosing. Pediatrics, 106 (6), 1344–1348. 7. Johnson, D., Jacobson, S., Edney, P., Hadfield, P., Mundy, M., & Schuh, S. A. (1998). Comparison of nebulized budesonide, intramuscular dexamethasone, and placebo for moderately severe croup. New England Journal of Medicine, 339 (8), 498–503. 8. Geelhoed, G., Turner, J., & Macdonald, W. (1996). Efficacy of a small single dose of oral dexamethasone for outpatient croup: A double blind placebo controlled clinical trial. British Medical Journal, 313, 140–142. 9. Kermode-Scott, B. (2004). Corticosteroids may be effective for most cases of croup, study shows. British Medical Journal, 329, 762. 10. Wheeler, D., Kiefer, M. Poss, W. (2000, June 1). Pediatric emergency preparedness in the office. American Family Physician, 61(11), 3333–3342. 11. Morens, D. (1999). Death of a president. New England Journal of Medicine, 341(24), 1845–1850. 12. Low, Y., Leong, J., & Tan, K. (2003). Paediatric acute epiglottitis re-visited. Singapore Medical Journal, 44 (10), 539–541.

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Chapter

7

Bronchiolitis Chapter Outline DEFINE • Define bronchiolitis • Define respiratory syncytial virus (RSV) DESCRIBE • Describe the clinical presentation of bronchiolitis • Describe who RSV bronchiolitis affects DISTINGUISH • Asthma • Bacterial tracheitis • Croup RESEARCH • Relevant research on bronchiolitis • Relevant research on RSV

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TREATMENT • Treatment options for patients with bronchiolitis • Treatment options for patients with RSV • Respiratory therapist’s role in the management of patients with RSV bronchiolitis

Key Terms Bacteremia Bronchiolitis Bronchodilator Meningitis Respiratory syncytial virus (RSV) Ribavirin Small particle aerosol generator (SPAG) Synagis

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Chapter 7 Bronchiolitis

INTRODUCTION

Winter tends to be a busy time for a respiratory therapist working in the emergency room, particularly at a children’s hospital. This is especially true at night, when respiratory symptoms among babies appear to worsen. Typical symptoms such as high fever, runny nose, and wheezes are all evidence of a long night in the emergency room. Although some symptoms appear similar to children with croup and asthma, there are distinctions among the various conditions. It is not unusual for a respiratory therapist to be directly in the face of an infant who is coughing and sneezing. A good assessment of an infant requires direct contact. In many instances, the child’s symptoms may mimic asthma or asthma-like symptoms; however, a runny nose and thick mucus are usually the typical signs of respiratory syncytial virus (RSV). This virus masks itself with symptoms similar to that of the common cold. So be aware. DEFINE

Bronchiolitis is defined as an acute, highly infectious, lower respiratory tract infection.1 Deborah Levine et al., in their 3-year multicenter study, define it as “either wheezes alone or chest retractions in association with an upper respiratory infection.”2 Bronchiolitis is most often caused by the respiratory syncytial virus (RSV); however, it has been caused by other viruses such as human metapneumovirus, adenovirus, parainfluenza, rhinovirus, and influenza.3,4 Respiratory syncytial virus itself is a medium-sized RNA virus and is classified as a paramyxovirus.5,6 RSV begins in the nasal epithelial cells and then replicates itself in the host cell, ultimately destroying the host cell, giving it the ability to reproduce in other uninfected cells. The virus can travel from cell to cell and easily spread to the lower respiratory tract, where it does the most damage. Craig Black at the University of Toledo states that children with RSV are predisposed to hypersensitive airways and possibly asthma later in life.2,7 This chapter focuses on RSV as the cause of bronchiolitis because research suggests it seems to be the virus that is highly linked to recurrent wheezes.4 It is most problematic in children under 2 years old and occurs most often in the fall and winter months. This virus is transmitted by fomites (objects or substances other than food capable of trans-

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mitting an infection) through infected secretions. Although RSV is easily transferable, it is critical that respiratory therapists and all other healthcare providers practice good hand washing between patients. Most of these patients will be in isolated rooms that may require the respiratory therapist to also wear an isolation mask. This is an effective means of controlling the spread of RSV. DESCRIBE

Bronchiolitis has been described as an inflammation of the bronchioles that cause obstruction to the lower respiratory tract. Common symptoms include the following: • • • • • • • •

Low-grade fever Runny nose Cough High respiratory rate Retractions Nasal flaring Inability to eat Cyanosis

Definitive diagnosis for bronchiolitis is a nasopharyngeal culture; however, a good history of the illness and clinical symptoms is helpful in this determination.8 Bronchiolitis has been described as an acute inflammatory cell response around the bronchioli with the appearance of granulocytes and mononuclear cells. This mediated response causes an accumulation of neutrophils and the sloughing of epithelial cells into the peripheral airways. This sludge can cause obstruction of the airway and hyperinflation of the lungs, which translates into increased respiratory distress symptoms.9 Whom Does Bronchiolitis Affect? Bronchiolitis affects infants and very young children and occurs mainly during winter months, commonly known as the cold and flu season. It has caused millions of deaths to children under 5 worldwide.7,10 In the United States alone, research estimates that 100,000 to 125,000

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hospitalizations and up to 450 deaths are attributed to RSV annually, which further adds to an overburdened healthcare system.7,10 DISTINGUISH

RSV bronchiolitis has been an ongoing public health concern and has reached epidemic proportions; however, there is a need to distinguish the signs and symptoms of RSV bronchiolitis from other more menacing conditions. Some research suggests that infants who present in the emergency room with a fever of unknown source should complete a full sepsis workup to ensure that they are not at risk for a more serious illness like meningitis or bacteremia.2,11 Although this is common medical practice, the question of whether a full sepsis workup provides any more information is still being debated. Most doctors err on the side of safety and complete a full sepsis workup for a child with a fever of unknown origin. As mentioned, fever is a symptom of bronchiolitis, and as with other viral infections, the fever can get progressively worse. Given the nature of viral infections, an accurate diagnosis of RSV bronchiolitis is crucial because this will guide the medical team to begin therapy sooner and with the correct medications. Care must be made to distinguish bronchiolitis from the following: • Asthma—a chronic inflammation of the airways with reversible episodes of obstruction caused by an increased reaction of the airways to various stimuli.12 Similar to bronchiolitis, children with asthma can have wheezes, coughing, and retractions. Asthma symptoms can be classified as mild, moderate, or severe. Asthma differs from bronchiolitis in that asthma has no cure; however, with proper medical management, asthma can be managed with short-acting bronchodilators and inhaled corticosteroids. • Bacterial tracheitis—an uncommon upper respiratory infection that obstructs the airway. Symptoms of bacterial tracheitis are similar to those of croup and epiglottitis. Bacterial tracheitis onset is rapid, leading to acute respiratory distress and airway compromise much faster than either croup or epiglottitis.13 Although children with bacterial tracheitis exhibit signs of respiratory distress similar to bronchiolitis, the events precipitating the distress tend to be dif-

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ferent than those for bronchiolitis. Bacterial tracheitis is generally treated with antibiotics. • Croup—a viral condition that affects the subglottic tissue, causing it to swell and obstruct the airway. It is caused most often by the parainfluenza virus.13 Children with croup display signs of respiratory distress; however, in mild cases, rarely is it necessary to seek medical attention. Children with croup display the cardinal signs of a barky cough and inspiratory stridor. Moderate to severe cases of croup may require medical attention; however, the management of this condition is different than that of bronchiolitis. Croup is generally treated with intravenous steroids and/or racemic epinephrine in more moderate and severe cases. RESEARCH

RSV was recognized more than 140 years ago, but was first described in 1963 by Robert Chanock and his research team in the medical journals.5,7 Chanock and his team identified the characteristics of this virus and gave it the name of respiratory syncytial virus. His team exposed a group of chimpanzees in a medical laboratory to a respiratory virus and observed the chimpanzee illness. It was first believed that the illness was due to the chimpanzee coryza agent, but it was later discovered that the infection was related to the chimpanzees’ caretakers rather than the chimpanzees themselves.5,7 They discovered that when caretakers moved from one object to another object, they transferred the virus from one animal to another. Chanock’s research clarified the damage caused by the virus and its effect on the airway and lung tissue following an infection. 5,7 As recently as 2008, scientists continued to ponder the epidemiology of RSV bronchiolitis and its impact on early infancy. Jurgen Schwarze, MD, reports in Pediatric Infectious Disease Journal that there appears to be a link between the dendritic cells and the body’s adaptive immune response. Schwarze suggests that in murine models plasmacytoid dendrite cells seem to limit the viral replication, which ultimately decreases the inflammation commonly seen in bronchiolitis. He further points out that as research continues, it may be beneficial to target lung dendrite cells in the development of drugs for treatment or possibly a vaccination.9

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Bronchodilator therapy has been studied and has been found to be supportive therapy. Gadomski and Bhasale reviewed 22 clinical trials representing 1,428 infants who received bronchodilator therapy.1 In 8 of the trials, or 468 infants, there was no improvement in 43% of infants who received bronchodilator therapy versus 57% of infants who received the placebo.1 The results are not surprising because the research conducted by Black concluded similar findings.7 Research continues to show mixed results regarding the administration of bronchodilators via airway deposition. Less than 2% of the medication reaches the lungs, and less than 1% actually makes it to the lung tissue. It was shown that the majority of the drug is in the mouth and throat and the rest is in the patient’s face.5 Daniel Levin et al. studied the effects of bronchodilator therapy in mechanically ventilated patients with RSV bronchiolitis. They found clinical insignificance in the use of bronchodilators with these 22 mechanically ventilated children with RSV. In contrast, their study did show a significant increase in the side effects from the use of bronchodilators.14 There were similar findings in the study conducted by Totapally et al. who concluded that the use of bronchodilators, namely, racemic albuterol, did not appear to improve the management of ventilated patients; however, they did indicate that one limitation of this study was the small sample size.15 In moderate to severe RSV bronchiolitis, there may be evidence of wheezes due to narrowing of airways filled with mucus. Brian Kuzik, MD, and his colleagues conducted a study that showed that nebulized hypertonic saline may be efficacious in the treatment of infants with RSV bronchiolitis.16 Hydration and good pulmonary hygiene has been shown to improve clinical symptoms. Although bronchodilators may be helpful in the short term, research shows limited benefits in the improvement of symptoms associated with RSV bronchiolitis. The treatment section will highlight other therapeutic options in the treatment of bronchiolitis. TREATMENT

There are a number of treatment options, though the most common therapies used by respiratory therapists include bronchodilator medication, bronchopulmonary hygiene, and mechanical ventilation. Although

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these treatment modalities are quite familiar to respiratory therapists, there is a vaccine available that targets infants and children considered at high risk for RSV bronchiolitis. Synagis (Palivizumab) In the 1990s, the vaccine Synagis was developed for human use. Synagis was approved by the Food and Drug Administration (FDA) for use in infants considered high risk, such as those with prematurity and chronic lung disease who are admitted to the hospital.5 Synagis is a monoclonal antibody that has been shown to prevent the development of lower respiratory infections. This medication is injected intramuscularly over a period of 3 months prior to and during the RSV season. Bronchodilators Albuterol and Xopenex Although there are a number of treatment options, bronchodilator medications are the most common therapy used by respiratory therapists. It is important to determine the appropriate dosing regimen. To do so, it is best to use the age and weight of infants and children. The medication that is likely to be administered will be either albuterol or Xopenex. There is still a tendency to use albuterol over Xopenex, guided more by cost than the efficacy of the drug. The medications are similar in nature, and neither offers a significant benefit over the other. The decision to use albuterol versus Xopenex will depend entirely on the clinician’s judgment and the patient’s needs. An infant less than 3 months old will likely use a dose that is less than 2.5 mg for albuterol or 0.31 mg for Xopenex. Table 7-1 illustrates typical doses for infants and children based on weight.

Table 7-1 Typical Doses of Short-Acting Beta Agonists Used in the Treatment of Bronchiolitis

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Albuterol

MDI Albuterol

Xopenex

Under 5 kg

1.25 mg

1–2 puffs

0.31 mg

Over 5 kg

2.5 mg

1–2 puffs

0.63 mg or 1.25 mg (weight dependent)

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Figure 7-1 Albuterol and Xopenex packaging.

Remember, it is imperative to read the label carefully on every vial because packaging for these medications is similar (Figure 7-1), which can lead to administration of the wrong medication or the wrong dosage. This is SUPER important in the NICU and PICU areas. Racemic Epinephrine Black’s review of various research studies shows that some medical centers were using racemic epinephrine as a bronchodilator.7 Although it is true that racemic epinephrine does have bronchodilation properties, the disadvantages of this drug may outweigh the advantages, so care should be made when recommending its use, especially because other more proven drugs are available. One advantage of racemic epinephrine is that it is a quick-acting beta agonist to the bronchial smooth muscles of the pulmonary system; one disadvantage is its cardiovascular side effects, including tachycardia and increased blood pressure.

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Figure 7-2 Infant and pediatric mask attached to small volume nebulizer


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Figure 7-3 Pediatric mask attached to a MDI holding chamber

Delivery Devices Small Volume Nebulizer (SVN) or Metered Dose Inhaler (MDI) For babies 3 months and older, use a pediatric or infant mask (see Figure 7-2) connected to a small volume nebulizer to deliver the medication or an appropriate size MDI with a mask (see Figure 7-3) for administration of either albuterol or Xopenex. Xopenex is available as an MDI. For babies from birth to 3 months, use an infant mask connected to a small volume nebulizer to deliver the medication. Most researchers agree that the blow-by method is not the optimal delivery mechanism for infants. This was certainly evident in the National Asthma Guidelines. Although the diagnosis is bronchiolitis, respiratory therapists are really dealing with the wheezing aspects (bronchoconstriction) of the condition for which it is very important to get the most medications to the lung tissue as quickly as possible. For delivery in line with a high flow nasal cannula, Figure 7-4 shows how to place the nebulizer in line. The flow to the nebulizer may have to be adjusted in order to adequately deliver the medication through the nasal cannula. Infants receiving nebulizer medication through a high flow nasal cannula should always be monitored.

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Figure 7-4 High flow nasal cannula with a small nebulizer in line

Ribavirin (Virazole) Ribavirin is delivered through a small particle aerosol generator (SPAG). In the early 1990s, it was common practice to use this medication and delivery device to treat babies with RSV bronchiolitis. In most cases, the use of the SPAG unit was more common in the pediatric general care area rather than the NICU. Patients who received ribavirin typically had some type of cardiac defect, were diagnosed with chronic lung disease, or had some condition that caused immunosuppressant, such as HIV or organ transplantation.8 This practice has mostly been abandoned due in part to the cost of the drugs, the high risk of occupational exposure to the healthcare professional from the ribavirin medication, and the ability to deliver the medi-

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Figure 7-5 SPAG unit

cation in much easier and more cost-effective ways. A respiratory therapist practicing today may never have to set up a SPAG unit (Figure 7-5). Helium/Oxygen (Heliox) Research states that heliox has shown modest benefits in managing patients with moderate RSV bronchiolitis.5 This is due to the low density of helium and its ability to penetrate the narrowed airways. Heliox is a carrier gas and has been known to decrease turbulent flow in the airway and promote laminar flow. Heliox comes in three mixtures: 70–30, 80–20, and 60–40. Figure 7-6 illustrates the heliox setup for a patient with a nonrebreather mask, and Figure 7-7 illustrates heliox connected to a ventilator. One word of caution: the patient oxygen requirement should always be considered when using heliox. Failure to provide appropriate oxygen therapy while using heliox may result in inadequate oxygen to the patient. This is something to keep in mind.

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O2 tubing oxygen blender

3-way adapter

O2 tubing to adapter Tubing to Heliox tank

Figure 7-6 Heliox with nonrebreather mask

Mechanical Ventilation Mechanical ventilation is the ultimate respiratory support and should be considered only if all other therapies have failed. All respiratory therapists must consider that bronchiolitis is linked to mucus produc-

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Conventional ventilator

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Heliox regulator Heliox tank Air highpressure hose

Oxygen high-pressure hose Figure 7-7 Heliox in line with ventilator

tion, which will always decrease the diameter of the airway. With this in mind, be on the alert for potential air trapping. When deciding on ventilator settings, remember that the goal is to ventilate with the least amount of pressure to avoid barotrauma. Table 7-2 gives some recommended starting ventilator settings.5 Although these settings are mere guides, routine blood gases values and bedside monitoring of hemodynamic status are by far the best tools to ensure adequate oxygenation and ventilation. With regard to monitoring, noninvasive methods like pulse oximetry and the transcutaneous CO2 monitors are routinely used in the critical care environment.

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Table 7-2 Suggested Settings for Mechanical Ventilation Mode

Assist control SIMV with pressure control and pressure support APRV (These are three examples—your ventilator may have others modes that will work equally as well.)

Rate

12 to 20 breaths/minute

Tidal volume

4 to 6 ml/kg or 5 to 7 ml/kg based on ideal body weight and your hospital specific protocol

Oxygen

FiO2 to keep SaO2 greater than 90%

PEEP

Titrate PEEP levels to maintain the lowest PEEP level to keep lungs open at the end of exhalation while ensuring an acceptable PaO2 (see Table 1-4).

Flow

Some ventilators may automatically adjust flow; if not, flow should be adequate to meet the patient inspiratory flow demand.

I:E ratio

1:2 If using APRV, the I:E ratio may be inversed.

Inspiratory time

0.8 to 1 second when using either AC or PC. This may be different if using APRV.

Trigger or sensitivity

Flow trigger 1 to 3 L/min or pressure trigger 0.5 cm to 2 cm H2O

Summary

✔✔ This chapter described bronchiolitis RSV as an acute highly infectious, lower respiratory tract infection caused most often by the respiratory syncytial virus. ✔✔ RSV occurs in the fall and winter and affects mostly children under the age of 2. ✔✔ RSV is transmitted by contact with innate objects that harbor infected secretions. Children who show symptoms of bronchiolitis RSV will display a low-grade fever, runny nose, and/or coughing. ✔✔ Symptoms that are moderate to severe will include retractions, tachypnea, nasal flaring, and cyanosis. ✔✔ In order to get a definitive diagnosis of bronchiolitis RSV, a nasopharyngeal culture is obtained. ✔✔ Bronchiolitis RSV is self-limiting, and patients recover within a few days; however, children who suffer more severe symptoms of bronchiolitis RSV may require more intensive care.

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✔✔ The role of the respiratory therapist becomes more evident when the condition worsens to the point of respiratory failure. This point is made clearer when mechanical ventilation is required. References 1. Gadomski, A. M., & Bhasale, A. L. (2006). Bronchodilators for bronchiolitis. Cochrane Database of Systematic Reviews (3), CD001266.DOI. 2. Levine, A. Platt, S., Dayan, P., Macias, C., Zorc, J., Krief, W., et al. for the Multicenter RSV-SBI Study Group of the Pediatric Emergency Medicine Collaborative Research Committee of the American Academy of Pediatrics. (2004, June). Risk of serious bacterial infection in young febrile infants with respiratory syncytial virus infections. Pediatrics, 113 (6), 1728–1734. 3. Hall, C. B. (2001). Respiratory syncytial virus and parainfluenza virus. New England Journal of Medicine, 344 (25), 1917–1928. Retrieved March 8, 2008, from http://content.nejm.org/cgi/content/full/344/25/1917 4. Meissner, H., & Long, S. (2007). Respiratory syncytial virus infection and recurrent wheezing: A complex relationship. Journal of Pediatrics, 151, 6–7. 5. Polak, M. (n.d.). Respiratory syncytial virus (RSV): Overview, treatment, and prevention strategies. Retrieved March 8, 2008, from http://www.medscape.com/viewarticle/472399 6. Centers for Disease Control National Center for Infectious Disease Respiratory and Enteric Viruses Branch. (n.d.). Respiratory syncytial virus fact sheet. Retrieved March 8, 2008, from http://www.cdc.gov/ncidod/dvrb/respiratory/ rsvfeat.htm 7. Black, CP. (2003, March). Systematic review of the biology and medical management of respiratory syncytial virus infection. Respiratory Care, 48 (3), 209–233. 8. Kacmarek, R., Dimas, S., & Mack, C. (2005). The essentials of respiratory care (4th ed.). St. Louis, MO: Mosby Elsevier. 9. Schwarze, J. (2008). Lung dendritic cells in respiratory syncytial virus bronchiolitis. Pediatric Infectious Disease Journal, 27 (10), S89–S91. 10. Yorita, K., Holman, R., Steiner, C., Effler, P., Miyamura, J., Forbes, S., et al. (2007). Severe bronchiolitis and respiratory syncytial virus among young children in Hawaii. Pediatric Infectious Disease Journal, 26 (12), 1081–1088. 11. Titus, M.O., & Wright, S.W. (2003). Prevalence of serious bacterial infections in febrile infants with respiratory syncytial virus infection. Pediatrics, 112 (2), 282–284. Retrieved October 8, 2007, from http://www.pediatrics.org/cgi/content/ full/112/2/282 12. National Asthma Education and Prevention Program (NAEPP). (2007). Expert panel report 3: Guidelines for the diagnosis and management of asthma. Bethesda, MD: National Institutes of Health (NIH Pub. No. 08-5846). Retrieved February 22, 2008, from http://www.nhlbi.nih.gov/guidelines/asthma/asthsumm.htm 13. Cherry, J. (2008). Croup. New England Journal of Medicine, 358, 384–391. 14. Levin, D., Garg, A., Hall, L. Slogic, S., Jarvis, D., & Leiter, J. (2008). A prospective randomized controlled blinded study of three bronchodilators in infants with respiratory syncytial virus bronchiolitis on mechanical ventilation. Pediatric Critical Care Medicine, 9 (6), 1–7. 15. Totapally, B., Demerci, C., Zureikat, G., & Nolan, B. (2002). Tidal breathing flow-volume loops in bronchiolitis in infancy: The effect of albuterol. Critical Care, 6 (2), 160–165. 16. Kuzik, B., Al Qadhi, S., Kent, S., Flavin, M., Hopman, W., Hotte, S., et al. (2007). Nebulized hypertonic saline in the treatment of viral bronchiolitis in infants. Journal of Pediatrics, 151, 266–270.

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Chapter

8

Air Leak Syndromes Chapter Outline DEFINE • Define the following air leak lesions: Pneumothorax Pneumomediastinum Pneumopericardium Pulmonary interstitial emphysema (PIE) DESCRIBE • Describe the clinical presentation of the following air leak lesions: Pneumothorax Pneumomediastinum Pneumopericardium Pulmonary interstitial emphysema (PIE) DISTINGUISH • Distinguish pleural effusion from other conditions.

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RESEARCH • Relevant research on treatment strategies for air leak syndrome TREATMENT • Treatment options for patients with air leak syndrome

Key Terms Air leak syndrome Barotrauma Cardiac tamponade Pulmonary interstitial emphysema Spontaneous pneumothorax Tension pneumothorax Transillumination

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Chapter 8 Air Leak Syndromes

INTRODUCTION

Barotraumas are well described in the literature with respect to the adult patients; however, for infants and children, the research describes barotraumas in relation to other causes. For example, Meberg et al. indicate that pulmonary air leakage is often related to other procedures such as resuscitation and mechanical ventilation.1 Barotrauma is associated with an increase in chest pressure that causes injury to lung and heart tissue. According to the American Academy of Pediatrics (AAP), a child’s chest wall (see Figure 8-1) is very compliant and easily able to transfer en-

Figure 8-1 Child’s rib cage

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ergy to internal organs, frequently without evidence of injury.2 Wilkins et al. report that 1% to 2% of all infants demonstrated spontaneous pneumothorax shortly after birth. This is secondary to high transpulmonary pressure required to take the first breath.3 Conditions that are discussed most often are pneumothorax, pneumomediastinum, pneumopericardium, pulmonary interstitial emphysema (PIE), subcutaneous emphysema, and pulmonary air embolism. Subcutaneous emphysema and pulmonary air embolism are not addressed in this neonatal/pediatric guide. The author suggests that the reader refers to other well-noted authorities on these two topics. Because barotraumas are often attributed to the use of manual resuscitation and mechanical ventilators, incidences of barotraumatic lesions are quite high in infants suffering from the following conditions: respiratory distress syndrome (RDS), transient tachypnea of the newborn (TTN), and meconium aspiration syndrome (MAS).4 Respiratory therapists who work in neonatal and pediatric intensive care units (NICU/ PICU) must fully appreciate the impact of barotraumatic lesions when managing infants and children on a mechanical ventilator. This chapter highlights four of the more common barotraumatic lesions seen in the NICU/PICU units. DEFINE

Pneumothorax Pneumothorax is the most common presentation of barotraumas in infants, occurring in 1% to 2% of all newborns.3 Pneumothorax is the rupture of alveolar air from the external surface of the lung into the pleural spaces.1,3,4 There are two types of pneumothoraces: spontaneous and tension. • Spontaneous pneumothorax—free air in the pleural spaces resulting from a weakening alveolar membrane. Figure 8-2 illustrates a spontaneous pneumothorax. • Tension pneumothorax—occurs when the lung parenchyma has already suffered an insult. The lungs tend to mend themselves by developing scar tissue, which makes the lung wall tight, preventing

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Parietal pleura Air in the pleural space Wound site Lung Collapsed lung

Heart

Visceral pleura

Diaphragm

Figure 8-2 Spontaneous pneumothorax

anything from entering this area. Air that enters the lung parenchyma has nowhere to escape. The pressure that builds up inside the lung wall impacts all structures inside the chest wall. A shift in the cardiac structures, a decrease in venous return, and a decrease in cardiac output, are a few of the results from this condition. Pressure in the chest wall must be relieved as soon as possible or else the patient may suffer permanent consequences, including death. Figure 8-3 illustrates a tension pneumothorax.

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Figure 8-3 Tension pneumothorax

Pneumomediastinum Pneumomediastinum is a condition in which free air cuts through the pleural spaces and invades the area surrounding the heart. It has been described by Whitaker as air that highlights the border of the heart, but does not surround it.4 Moderate pneumomediastinum can have a significant impact on an infant’s blood pressure, according to Ibrahim Mohamed et al.5

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Pneumopericardium Pneumopericardium is a barotrauma in which free air cuts through the pleural space, the mediastinum, and surrounds the structures of the heart. Free air encircles the heart and decreases the heart’s ability to beat properly. The pericardial sac that contains the heart is filled with air; it causes an increase in pressure around the heart that ultimately results in cardiac tamponade. Pulmonary Interstitial Emphysema Pulmonary interstitial emphysema (PIE) is a diffuse hazy opacity of the lungs consistent with surfactant deficiency, according to David Berk and Laura Varich at Stanford University School of Medicine.6 Lane Donnely et al. describe PIE as solid linear or dot-like structures within air-filled cysts that differ in appearance from that of pulmonary emphysema.7 Simply put, PIE is free air that travels throughout the tissues of the lungs. The experts note there is an increased incidence of PIE with the prolonged use of mechanical ventilation, use of positive end-expiratory pressure (PEEP), use of high positive inspiratory pressure (PIP), and prolonged inspiratory times. Whitaker further describes that once a diagnosis of PIE is made, it can be categorized as one of the following: • Intrapulmonary interstitial pneumatosis—free air that remains inside the lung tissue • Intrapleural pneumatosis—free air that is outside the lung tissue4 PIE is characterized by compressing small airways and blood vessels leading to a ventilation and perfusion mismatch. This is seen as evidence of worsening arterial blood gases. DESCRIBE

Pneumothorax Pneumothorax is an abnormal collection of air within the pleura cavity that may have resulted from a rupture of a pulmonary bleb or a puncture to the chest wall. As stated earlier, there are two types of pneumothorax:

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spontaneous and tension. Although spontaneous pneumothorax is air that is in the pleural spaces, tension pneumothorax is air or gas that is trapped within the spaces and is under pressure. Spontaneous pneumothoraces in an adult patient may be asymptomatic, and on most occasions the pneumothorax will resolve on its own. There are times when the respiratory therapist will be asked to provide 100% pure oxygen therapy to an adult patient generally with a non-rebreather mask. The partial pressure of oxygen will displace the nitrogen into the pleural spaces, which will speed the resolution of the pneumothorax. On the other hand, a spontaneous pneumothorax in an infant or a child, even a small one, may not be as easy to manage as in the adult; therefore, the administering of oxygen therapy may not be as effective. Signs of spontaneous pneumothorax can include apnea, bradycardia, hypotension, cyanosis, chest wall dyssnchrony, and diminished breath sounds to the affected side. A word of caution: many of these signs and symptoms can reflect other conditions as well. If there is a delay in obtaining a chest x-ray, the best way to validate a spontaneous pneumothorax at the bedside of an infant is to transilluminate the chest wall with a fiber optic light source.3,4 Transillumination is a fairly common procedure in most NICUs; however, for an older child, a chest x-ray is still the standard procedure for diagnosing a pneumothorax. For small infants, transillumination is performed to light up the chest wall. It uses a fiber optic light source that helps the clinician pinpoint free air in the chest cavity. Whitaker describes a positive sign of a pneumothorax as an “abnormal finger of reflected light.”3,4 Kacmarek et al. suggest that a well-inflated lung will absorb most of the light from the transilluminator, and if there is an increase in the amount of light seen on the chest wall, then this might suggest free air in the chest cavity.5 It is very important to note that the signs and symptoms of a tension pneumothorax in children are much harder to detect due to their small chest wall, breath sound differences from one side to another, and jugular venous distention. Also, according to AAP, tracheal deviation may be undetectable in infants, especially those with short, fat necks.2

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Table 8-1 Signs and Symptoms of Pneumothoraces Pneumothorax: • Spontaneous (S) • Tension (T)

Pneumomediastinum

Pneumopericardium

Pulmonary Interstitial Emphysema

(S) Free air in the pleura spaces, causing a collapse of a lung (T) Free air in the pleura spaces that is under pressure

Free air that cuts through the pleura space and migrates to the mediastinum

Free air that cuts through the pleura space and migrates to the pericardial sac and surrounds the heart

Free air that causes the rupture of alveoli into the pulmonary microvascular spaces. Intrapulmonary interstitial pneumatosis Intrapleural pneumatosis

Signs and Symptoms of Pneumothorax, Pneumomediastinum, Pneumopericardium, and Pulmonary Interstitial Emphysema Tachycardia Tachypnea Cyanosis Restlessness Diaphoresis Narrowing pulse pressure Hypotension (late sign) Shift in position of the tracheal to the opposite side of the lesion (late sign) Shift in the point of maximum impact Absent or decreased breath sounds over the affected area Diminished breath sounds on the unaffected side Worsening arterial blood gases with a severe ventilation-perfusion mismatch Low oxygen saturation Jugular venous distention Asymmetrical chest movement Bulging intercostal muscles on the affected side

Table 8-1 describes the signs and symptoms of both spontaneous and tension pneumothoraces. Figure 8-1 is a good illustration of a child’s ribcage. A child’s ribcage is more pliable than adults, and there maybe no obvious rib fractures; however, in most children, the ribcage may simply compress inward, causing compression of the internal organs. Figure 8-2 illustrates a

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Pneumothorax Case Study Suppose that while working the emergency room, you are told that a head-on collision involving two passenger vehicles has occurred and a young child is one of the victims. When the rescue team arrived on the scene, they found a 5-year-old boy who had been unrestrained, riding in the back seat of the car. The emergency responder team reported that he had been tossed into the back of the passenger seat during the collision. The child is conscious, alert, and in no obvious respiratory distress. The child is placed onto a long spine board and is assessed by the emergency responder team before being transported to the hospital emergency department only 15 minutes away. Here is what you know: • Head-on motor vehicle crash at 40 mph. • Unrestrained 5-year-old-boy pushed into the passenger seat upon impact. • Child is conscious, crying, and restless. Emergency responders report no observations of respiratory distress. • Child is maintaining his airway; respiratory rate: 18-to 20-breaths per minute. Radial pulses: rapid and regular; skin: cool and moist; capillary refill time: 2 seconds; no gross bleeding. Upon the patient’s arrival at your emergency room, you place him on a device that can provide up to 100% of oxygen: possibly a non-rebreather mask. Because this is a trauma patient, he should come to the emergency room with a cervical collar and head block already in place. This ensures that the spine is immobilized during the transport to the hospital and while being examined in the emergency room. Ongoing assessments provide the following:

Blood pressure 92/58 mm Hg Pulse 130 beats/min, strong and regular Capillary refill time 3 seconds Respirations Greater than 40 breaths/min and labored Oxygen saturations 93% (on 100% oxygen) Signs and symptoms Chest wall abrasions, unilaterally diminished breath sounds on the affected side, tachypnea, dyspnea, tachycardia

Assessments now note the following: • • • • •

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Child’s level of consciousness has decreased. Increased respirations and more labored. Asymmetrical chest wall movement. Poor oxygen saturation despite 100% oxygen delivery device. Because this was reported as a head-on car crash, you are now thinking pneumothorax. Good job.

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spontaneous pneumothorax, whereas Figure 8-3 shows a tension pneumothorax. Once you’ve identified this patient as having a pneumothorax, be prepared to provide ventilatory assistance with a bag-mask device, should the child’s condition further decompensate. Figure 8-4 illustrates the use of a bag-mask device for a child. As always, respiratory therapists have been trained to manage a hand-resuscitator bag; however, keep in mind that aggressive manual ventilation can aggravate a pneumothorax, worsening the patient’s condition. It is preferable to ventilate with the lowest pressure (just enough to see the chest rise and fall) at the most appropriate respiratory rate for your patient. The respiratory rate should mimic the child’s normal ventilatory pattern. Manual ventilation is your initial step; yet, endotracheal intubation is the safest and most effective means of long-term ventilation until the underlying problem is resolved. Figure 8-5 illustrates endotracheal intubation of a child. Confirmed pneu-

Figure 8-4 Bag mask device for a child

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Figure 8-5 Endotracheal intubation

mothoraces must be relieved by needle aspiration. Figure 8-6 demonstrates where and how a pneumothorax is relieved. Pneumomediastinum Pneumomediastinum occurs when free air cuts through the pleural spaces and occupies the area around the heart. If this air invades the area surrounding the heart, called the mediastinum, we call it a pneumomediastinum. Whitaker describes it as air that highlights the border of the heart, but does not surround it.4 Pneumomediastinums are seen more often in traumatic chest injuries that rupture the main bronchus, which allows for movement of air into the mediastinum. Pneumopericardium Similar to pneumomediastinum, the air actually cuts through the mediastinum and surrounds the structures of the heart. Free air encircles the

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Rib

Skin Pectoralis muscle Intercostal muscle

Rib intercostal space Rib Neurovascular bundle

90˚ angle

Lung Parietal pleura Visceral pleura Rib

Figure 8-6 Placement of needle to aspirate a pneumothorax

heart and decreases its ability to beat properly. The pericardial sac contains the heart, and if air fills this sac, then it has no means of escaping, causing a buildup in pressure around the heart. The term cardiac tamponade means a collection of gas, fluid, or blood that acts to compress the rhythmic movement of the heart. A rapid deterioration in the patient’s hemodynamic status is evidence of cardiac tamponade. One of the more obvious signs in infants is sinus bradycardia, followed by poor oxygen saturation. This is not a good sign. Pulmonary Interstitial Emphysema (PIE) Whitaker and others agree that PIE occurs when free air manages to travel throughout the tissues of the lungs.4,8 This happens most often as the result of mechanical ventilation and the chronic use of high PEEP, high peak inspiratory pressure, and prolonged inspiratory times. Whitaker further reminds us that when PIE develops, it can be categorized as intra-

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pulmonary interstitial pneumatosis (free air that remains inside the lung tissue) or intrapleural pneumatosis (free air outside the lung tissue).4 PIE wrecks havoc on the small airways and compresses blood vessels, which leads to a ventilation perfusion mismatch, followed by a worsening of arterial blood gases. PIE is characterized by inflamed airways with high airway resistance that creates gas trapping, pulmonary overdistension, and alveolar disruption when other forms of mechanical ventilation are used.9 DISTINGUISH

What Does It Look Like on a Chest X-Ray? Spontaneous pneumothorax is described as a dark discoloration with no lung markings present. The affected lung looks collapsed, with little to no air inside. It may also show that the mediastinum appeared to shift to the opposite side from the pneumothorax.4 Tension pneumothorax is similar to a spontaneous pneumothorax, except the diaphragm on the side of the pneumothorax will be depressed and the intercostal spaces will be widened.4,8 To better describe this condition, consider air entering the pleura spaces on inspiration, but not being allowed to escape on expiration. The more air that is allowed inside the pleura spaces without the ability to escape, the more pressure is built inside the pleural spaces. An increase in free air will cause the heart and the lung on the affected side to be compressed. The chest x-ray will show that the hemidiaphragm will be pushed downward. Pneumomediastinum on a chest x-ray shows free air that does not surround the heart, but rather highlights the borders of the heart. This can be seen from a lateral view of the heart on the chest x-ray. Pneumopericardium on a chest x-ray shows free air that completely surrounds the heart. This is air that has collected inside of the pericardial sac. The amount of air around the heart could cause cardiac tamponade, which would reduce the cardiac output and lead to shock.4 Pulmonary interstitial emphysema (PIE) on a chest x-ray shows air from ruptured alveoli that can remain localized or can move quite easily into the interstitial spaces, and this can be seen as air surrounding

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the pulmonary vascular bed. This looks more like patchy white spots collected in fairly close proximity on one or more lobes of lung tissue. Some authors describe it as “dot-like structures” or a “line and dot pattern.”7 Still other authors describe it as a salt-and-pepper pattern. RESEARCH

Wilkins et al. report that most spontaneous pneumothorax in the neonate is linked to high transpulmonary pressure that the infant must overcome secondary to blockage of the lumen of bronchial tube. They suggest that this transpulmonary pressure could be as high as 100 cm H2O.3 Wilkins et al. further describe pneumothorax as either primary (without underlying lung disease) or secondary (with underlying lung disease). Their findings further suggest that primary pneumothorax generally occurs in late teenagers and patients in their early twenties.3 Pneumothorax, pneumomediastinum, and pneumopericardium are described in infants and children with the usual findings related to sources such as high peak inspiratory pressure generated by mechanical ventilators. Although these types of barotraumatic lesions are problematic, they are usually managed with a chest tube, which is described under the treatment section. Mohamed et al. report an interesting case of a 35-week gestational age baby with infantile polycystic kidney disease whose chest x-ray shows a moderate pneumomediastinum and the impact of this pneumomediastinum on the baby’s blood pressure. They indicated that within 2 hours, the blood pressure had dropped to the low 30s and pulse oximetry readings had dropped to the high 70s. They further reported that needle aspiration was not successful and only a chest tube inserted through the anterior mediastinum under guided ultrasound was successful in resolving this pneumomediastinum.5 As with all types of barotraumas, careful monitoring for changes in hemodynamic stability is the key to successful patient management. Changes tend to be quick and without warning. Neonatal experts agree that mere chest tube management does not always solve the problem caused by PIE. In fact, PIE causes worsen-

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ing blood gases and increased ventilation and perfusion mismatch that sometimes do not resolve for weeks. In the NICU, understanding pulmonary interstitial emphysema (PIE) is very important to respiratory therapists because many of these patients are a challenge to ventilate and may benefit immensely from ventilator strategies that decrease lung damage. J. Thomas Stocker and Madewell report that PIE occurs in approximately 5% of newborns with respiratory distress syndrome and appears as an uneven expansion of the lungs due to aspiration either in the uterus or during the first breath following delivery.10 David Berk and Laura Varich from Stanford University School of Medicine state that PIE is strongly associated with prematurity, respiratory distress syndrome, and mechanical ventilation.6 Berk and Varich further describe PIE as a diffuse hazy opacity of the lungs consistent with surfactant deficiencies; this was seen in a case they reported of an infant who was not mechanically ventilated.6 In their findings, the researchers cautioned radiologists to consider localized PIE as a differential diagnosis as evidenced from computer tomography (CT) imaging results.6 Lane Donnelly et al. describe PIE as solid linear or dot-like structures within air-filled cysts that differ in appearance from pulmonary emphysema.7 TREATMENT

Pneumothorax, Pneumomediastinum, and Pneumopericardium Size and severity are key factors in the treatment options for pneumothorax, pneumomediastinum, and pneumopericardium. Infants and children who have no respiratory symptoms may require only close monitoring. Patients who display serious respiratory complications may require needle aspiration to the affected area, followed by a chest tube insertion. Needle aspiration and chest tube placement are the options for pulmonary air leaks.3,4 Figure 8-6 depicts pleural decompression in a child with a pneumothorax. A needle is placed in the pleural cavity to allow air to escape and the affected lung to reexpand. As a reminder, it is not likely that you will be required to place a chest tube, but it is helpful to have an understanding of how the procedure is done.

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Pulmonary Interstitial Emphysema The literature states that treatment of PIE is often nonsurgical, provided there is prompt recognition of the condition.6 The research has reported a few treatment options, which are discussed in this section. Ventilator Strategies Although this section will highlight some of the more common ventilator strategies used in most NICU and PICU, each of these strategies provides advantages as well as disadvantages. Regardless of the type of ventilator used, each is considered supportive therapy and not designed to be curative. Conventional Ventilation Conventional ventilation is the delivery of positive pressure to the lung tissue with a machine that is pneumatically driven and electrically operated to provide a flow of gas via an artificial tube to the patient’s airway. It is the first strategy used in the treatment of infants with respiratory distress syndrome who subsequently develop PIE. The current standard of care is to employ a ventilator strategy that would promote lower pressures, lower volumes, lower FIO2, and lower inspiratory time. Inasmuch as our positive pressure ventilator can deliver these parameters, oftentimes it is not enough to promote adequate ventilation and oxygenation. Sometimes it becomes necessary to increase the ventilator settings to undesirable pressure, volumes, FIO2, and inspiratory times. Infants with RDS and PIE will require numerous ventilator changes in order to optimize the infant’s blood gas values. In PIE, conventional ventilation is often supplanted by the use of high-frequency ventilation. There are two types of HFV units seen in the NICU that the literature support as having the ability to deliver either low tidal volume or low peak inspiratory pressure: high-frequency jet ventilator (HFJV) and high-frequency oscillator ventilator (HFOV). High-Frequency Jet Ventilator (HFJV) The HFJV developed by J. Bert Bunnell, ScD is called the Life Pulse High Frequency Ventilator (see Figure 8-7). The Life Pulse is pressure-limited and time cycled with adjustable PIP, rate, and Inspiratory time (I-time). Exhalation is passive. The Life Pulse

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Figure 8-7 High Frequency Jet Ventilator

delivers small tidal volumes (VT) at rapid rates via a special ET tube adapter (see Figure 8-8) with a built-in jet nozzle. Connecting this adapter to a patient’s endotracheal or tracheotomy tube enables tandem use of a conventional mechanical ventilator. Gas flow is feedback controlled by matching monitored PIP with set PIP. Monitored servo-controlled (driving) pressure (Servo Pressure) is used to detect changes in lung compliance and resistance, and mishaps such as accidental extubation, pneumothorax, bronchospasms, and so on. The Life Pulse is very efficient at CO2 elimination, which makes it ideal in managing patients with PIE. Figure 8-9 shows the Jet patient box, and Figure 8-10 shows the connection of the Life Pulse to a conventional ventilator. Although some clinicians use the Life Pulse for premature in-

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Figure 8-8 Special ET tube adapter

Figure 8-9 HFJV jet box

fants with uncomplicated RDS, it is most often used to rescue infants and children with lung injury. PIE is the most common indication for the Life Pulse because it automatically improves ventilation/perfusion matching and facilitates healing by reducing mechanical ventilation of the most affected areas of the injured lungs. PIE is characterized by inflamed airways with high airway resistance that creates gas trapping, pulmonary overdistension, and alveolar disruption when conventional mechanical ventilation is used. Because high airway resistance deters high velocity inspirations, resolution of PIE is much more likely using the Life Pulse.7 Several research studies were done with the Life Pulse HFJV by Martin Keszler, MD, at Georgetown University Hospital, Washington, D.C., where he has demonstrated successful use of the HFJV in low birth weight infants. The goal is to provide adequate ventilation and maintaining adequate oxygenation while avoiding high alveolar pressures and large tidal volumes, which should lower the risk of an infant developing bronchopulmonary dysplasia (BPD). Dr. Keszler and other neonatologists around the country have seen significant improvement in the outcome of infants diagnosed with PIE while using the HFJV.11 Table 8-2 describes the starting settings on the HFJV. Keep in mind that your facility and your medical team may differ slightly in the

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Table 8-2 Suggested Starting Settings for HFJV Using Life Pulse HFJV Rate

240 best for severe pulmonary hyperinflation and severe PIE; this facilitates long I:E ratios 420 used with infants who weigh 2000 grams or less Reduce rate on CV to 5 bpm—this enables sigh breaths and facilitates fresh flow of gas to the tracheal.

I-time

Default I-time is set at 0.02 seconds—this works well in most situations.

PIP

Start PIP 1–2 cm H2O above what the PIP was set on the conventional ventilator. Watch for chest vibration; adjust PIP according to your PaCO2 from your blood gas. Fine Tuning PIP: Remember that PaCO2 is critical, and it may be necessary to raise the PIP on the HFJV to levels that seem high; yet the principle behind HFJV is small tidal volumes and very low I-time so the HFJV pressure amplitude decreases quickly as the tiny breaths approach the alveoli.10

Tidal volume

Generates tidal volumes less than anatomical dead space

Oxygen

FiO2 to keep SaO2 greater than 90% Focus on MAP to maintain oxygenation—it is possible you will use higher PEEP to maintain MAP. Keep in mind that LifePulse uses very small tidal volumes and very short I-time so you have a lower risk of creating volutrauma.

PEEP

To find optimal PEEP, see Table 8-3. PEEP is set on the CV and is monitored on the HFJV. The PEEP that is set on the CV should reflect the same PEEP on the HFJV.

Inadvertent PEEP

If PEEP is higher on HFJV than set PEEP on CV, this is an indication of auto-PEEP. This will force Servo Pressure to fall and allow an increase in PaCO2.

Monitoring

Remember that HFJV is used as a lung protective strategy to promote healing and lung growth. You will need the following: Patience while the infant’s lungs heal Pulse oximeters and or transcutaneous monitoring Arterial line to monitor blood gases

Weaning

Once there are signs of improvement based on improved blood gases, hemodynamic stability, and overall patient appearance, then weaning can begin. Dr. Bunnell recommends that patients can and should wean directly from HFJV to CPAP in order to maintain lung protection ventilation. PIP to lower than 20 cm H2O Lower rate to minimize interference with spontaneous breathing A PIP of less than 16, a MAP of less than 8 cm H2O, FiO2 of 30% or less, and spontaneous breathing is evidence of an infant who should be transitioned to a short trial ET CPAP on CV. If infant does well with this trial, this is a good indication that NCPAP at 8 cm H2O will be tolerated.

Note: It is recommended to start HFJV as soon as possible to minimize the risk of volutrauma from conventional ventilation (CV). It may be that in your institution, there other guiding principles used to initiate high-frequency jet ventilation.

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Figure 8-10 HFJV connected to the conventional ventilator

starting settings, depending on the condition of the baby and the underlying pathophysiology of the disease being treated. Because a respiratory therapist is a member of the team, your opinion counts with regard to the proper ventilator settings, so be prepared. In recent years there has been increasing interest in the use of HFJV in patients with evolving or established chronic lung disease. These patients are characterized with having lungs that are hyperinflated and retaining CO2. The Life Pulse is used at a low rate (240–300 bpm) in these patients to address the hyperinflation by lengthening the exhalation time and establishing a longer I:E ratio (1:9 – 1:12). This allows for more effective exhalation and enhanced CO2 removal.

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How to Use the Life Pulse HFJV: Seven Steps to Success Life Pulse HFJV clinical strategies have evolved from the accumulated experience of treating tens of thousands of infants as well as from randomized controlled studies. The following seven steps are a culmination of what Dr. Bunnell has learned over the past 2 decades of clinical use. 1. Start HFV ASAP. Many clinicians wait until an infant sustains significant lung injury before implementing HFJV. Unfortunately, a failing respiratory system leads to failure of other organ systems, and once the patient reaches that point, chances for recovery are slim. The only significant difference between survivors and non-survivors in one Life Pulse study was the time they spent on CMV prior to starting HFJV (4 days vs. 10 days respectively). The sooner HFJV is started, the better the patient’s chance of recovery. 2. Select start-up Life Pulse settings based upon patient size and pathophysiology. Monitor and record current CMV or HFOV settings using the LifePort ET tube adapter with the Life Pulse in standby mode. On-Time: The default On-Time (I-time) setting of 0.02 sec. works best in most situations, so leave it set there most of the time. Rate: Using 420 bpm usually works fine for patients 2000 grams or less. Larger preemies, term infants, and infants with pulmonary hyperinflation, severe PIE, and other lung conditions in which exhalation is compromised by airway inflammation or obstruction do better on lower rates. With I-time set at 0.02 sec, lower rates create longer exhalation times. The lowest Life Pulse rate (240 bpm), where I:E = 1:12, is the best choice for pulmonary hyperinflation and severe PIE. Longer exhalation times facilitate diffusion of gas out of interstitial space and allow hyperinflation to resolve. Minimizing the number and size of CMV breaths is critical in these patients. PIP: Start the Life Pulse with PIP set at 1–2 cm H2O < the CMV or HFOV PIP monitored by the Life Pulse. Press ENTER, verify that the chest is vibrating, and adjust PIP as necessary to get appropriate PaCO2. 3. Maintain pre-Life Pulse MAP for better oxygenation at start-up. Focusing on MAP instead of PEEP reminds us what’s most important for oxygenation. In general, you will use higher PEEP with the Life Pulse to support MAP, which is safe because the Life Pulse uses small tidal volumes and a very short I-time (0.02 sec.). Once you have started the Life Pulse, reduce CMV support to 5 bpm and increase PEEP as needed to match the monitored pre-Life Pulse MAP. (If you are switching from HFOV to HFJV, you can sometimes use less MAP [–1 to –2 cm H2O].) We will optimize PEEP in step 5. (continues)

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4. Fine-tune PIP to manage PaCO2. Use transcutaneous CO2 monitoring and get a blood gas sample within 20 minutes of starting the Life Pulse to see if PIP is adequate. Sometimes, clinicians are surprised to see how much PIP it takes to ventilate premature infants. Remember: It is volume—not pressure—that creates lung injury, and the Life Pulse uses extremely small tidal volumes (~ 1 ml/kg). HFJV pressure amplitude decreases quickly as the tiny breaths approach the alveoli. So raising PIP is the gentlest way to lower PaCO2. A Life Pulse VT delivered with a PIP of 50 cm H2O is still much smaller than a CMV VT delivered with a PIP of 20 cm H2O due to the difference in I-times. 5. Use CMV “sigh” breaths to find optimal PEEP. Sigh breaths are contraindicated in the presence of severe lung injury, and we can use the removal of the last 5 CMV bpm from step 3 to find optimal PEEP. Adjust FiO2 to achieve the desired SaO2 with the patient stabilized on the Life Pulse with CMV at 5 bpm. Then, switch CMV to CPAP mode and watch the pulse oximeter. If SaO2 drops, increase PEEP 1–2 cm H2O, re-institute the 5 bpm, and repeat the sequence. Once SaO2 is stable with your CMV in CPAP mode, leave it in CPAP mode most of the time. However, some patients like a sigh breath rate of 2–5 bpm. Switch CMV back to 5 bpm as needed to re-recruit collapsed alveoli after suctioning, repositioning, and so on, and whenever you want to test for adequate PEEP as just described. Moving CMV back to CPAP mode once oxygenation improves (after 15 minutes or so) will minimize the size and number of larger VTs delivered to the patient and help avoid “volutrauma.” If cardiac output suffers with higher PEEP, back off a little. Here you can use a few CMV sigh breaths per minute to compensate for inadequate MAP in the hope of improving venous return of blood to the heart. (Remember: It is O2 delivery to the tissues that determines optimal PEEP.) Some of the newest generation ventilators make it difficult to keep the CMV in CPAP mode with the LifePulse due to their apnea detection systems. With these ventilators, use the lowest IMV settings possible by minimizing rate, PIP, and I-time. Then, turn up each setting as necessary when you want to provide effective sigh breaths. 6. Be patient, and use Servo Pressure, pulse oximetry, and transcutaneous CO2 monitoring to stay on track. Recognize that weaning will be possible only when the patient’s medical condition is improving. There is a time for initial stabilization of the patient, and a time for weaning. In between those times, focus on maintaining good blood gases and let HFJV lung protective ventilation facilitate healing and lung growth. Servo Pressure responds to changes in the patient’s lung mechanics. Rising Servo Pressure is generally a good sign. Falling Servo Pressure may indicate deterioration and should be addressed quickly. Any time you get a Servo Pressure alarm, you should investigate. Is the ET tube poorly positioned or plugged? Is the patient’s compliance getting worse? Or, is it just time to suction the airway?

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If monitored PEEP on the Life Pulse is higher than set PEEP on the CMV, you have inadvertent PEEP, which will force Servo Pressure down and allow PaCO2 to rise. Turn the Life Pulse rate down in increments of ~60 bpm until the inadvertent PEEP goes away. Then, manage PaCO2 by adjusting HFJV PIP as needed. If hyperinflation is not present, you can increase the Life Pulse rate to lower PaCO2 as you would with CMV. VT is independent of rate with the Life Pulse, so increasing rate increases minute ventilation and lowers PaCO2. Fight PEEPaphobia! PEEP is the primary determinant of mean airway pressure and oxygenation (PaO2). It also helps splint airways open in older babies who get hyperinflated, which should decrease expiratory resistance and hyperinflation. 7. Wean directly to nasal CPAP. Once the patient has cleared his maintenance phase, weaning can begin. Our natural instinct is to wean patients from HFJV back to CMV at the first signs of improvement. At best, this approach may prolong your patient’s time on mechanical ventilation. At worst, whatever condition caused you to go to the HFJV in the first place may reappear. Focus on maintaining lung protective ventilation all the way to CPAP. Wean PIP in response to improved PaCO2. When PIP is below 20 cm H2O, you can lower Life Pulse rate to minimize interference with spontaneous breathing. At 240 bpm, I:E = 1:12; therefore, the patient is spending most of his time on CPAP already! Once the Life Pulse PIP £ 16 cm H2O, MAP < 8 cm H2O, FiO2 < 30%, and the baby is breathing regularly, you should consider transitioning to CPAP. A short trial of ET CPAP on the CMV will give you a good indication of how the patient will tolerate NCPAP. Don’t worry about weaning PEEP too much. When you pull the ET tube, match your NCPAP to the final Life Pulse MAP. You can implement NCPAP at 8 cm H2O if that is how much is needed, and your baby will breathe a lot easier without an ET tube. See Table 8-3 for schematic of finding optimal PEEP with the use of Life Pulse Jet Ventilator. Testing the Life Pulse Prior to setting up the Life Pulse HFJV, you must perform two tests to ensure proper ventilator operation. They are the systems test and the functional test. Table 8-4 will provide you with instructions on how to conduct these tests. The system test assures that all critical functions on the Life Pulse are working. The functional test assures that monitored pressures are stable, the alarms are active and the pressure transducer is calibrated. Table 8-5 highlights some of the more common alarms, with troubleshooting tips to successfully ventilate an infant on HFJV.

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Finding Optimal PEEP during HFV *

Table 8-3 Finding Optimal PEEP During HFV*

Switch to HFV from CV at same MAP by adjusting PEEP. Reduce IMV Rate to 5 bpm. Note current SaO2 on pulse oximeter.

Switch CV to CPAP mode.

NO

Does SaO2 drop? (Wait 1 - 5 min.)

PEEP is high enough, for the moment.

YES

Use IMV = 0 - 3 bpm with IMV PIP 20 - 50% < HFV PIP

PEEP is too low.

(hours later) Switch back to IMV.

YES

Does FiO2 needs to be increased?

Increase PEEP by 1 - 2.

Wait for SaO 2 to return to acceptable value. (It may take 30 min.)

NO Keep PEEP at this level until FiO2 < 0.30

Don’t be shocked if optimal PEEP = 8 – 12 cm H2O!

* when switching from CV to HFV. Warnings: Lowering PEEP may improve SaO2 in some cases. Optimal PEEP may be lower in patients with active air leaks or hemodynamic problems. Using IMV with high PEEP is hazardous. Do not assume high PEEP causes over-expansion.

1- 800-800-4358

www.bunl.com

02559-00.1C

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Table 8-4 Calibrating the Life Pulse HFJV Provide gas source.

Connect output of air/oxygen blender to gas INPUT connector of rear panel of the Life Pulse HFJV.

Provide electrical power.

Plug Life Pulse into electrical outlet.

Turn on Life Pulse.

Press ON/OFF switch on front panel. Press SILENCE button to quiet “Power ON” alarm.

Install cartridge/circuit.

Cartridge and circuit is installed in the front panel of the LifePulse HFJV (see Figure 8-8).

Attach sterile water.

Connect sterile water bag to water inlet on humidifier cartridge, and unclamp tubing.

Attach test lung with LifePort adapter to circuit and patient box.

Connect pressure monitoring tube of the LifePort adapter to patient box, and connect green delivery tube of the Life Pulse circuit to the jet port on the LifePort adapter.

Perform systems test.

With the test lung attached, press TEST button and verify that LifePulse returns to standby mode with audible alarm sounding. Press SILENCE button to quiet “PASSED TEST” alarm.

Perform functional test.

Perform a functional test. Enter default settings (PIP 20, Rate 420, On-Time 0.20) while attached to test lung. Verify that READY condition can be met, the monitored pressures are stable, and the PEEP is zero with no CV attached.

Remove and save test supplies.

Remove the test lung. Save tube and test lung for future tests.

Table 8-5 Common Troubleshooting Techniques for the Life Pulse HFJV Alarm

Possible Problem

Suggestion for Correction

High PIP

ET tube improperly positioned, kinked, or obstructed.

Reposition, unkink, or suction ET tube. (Check for the possibility of reintubation.)

Loss of PIP

Pressure monitoring tube obstructed, kinked, or disconnected.

Unkink or reconnect pressure monitoring tube, or flush with 3–5 cc of air while jet is running and in READY mode. May need to press ENTER to resume ventilation if READY light is off. Reevaluate cartridge temp setting. Suction patient is necessary.

Hi-Lo jet insufflation tube kinked or disconnected.

Unkink or reconnect Hi-Lo jet insufflation tube.

Humidifier cartridge/circuit leaking, kinked, or improperly installed.

Inspect humidifier cartridge/circuit for leaks, kinks, or poor connections, and correct condition. (continues)

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Table 8-5 Common Troubleshooting Techniques for the Life Pulse HFJV (Continued) Alarm

Possible Problem


Unstable PIP

Water or secretions in or around tip of pressure monitoring tube.

Flush pressure monitoring tube with 3–5 cc air while jet is running and in READY mode. May need to press ENTER to resume ventilation if READY light is off. Reevaluate cartridge temp setting. Suction patient if necessary.

Conventional ventilator breaths or patient’s active spontaneous breathing affecting pressure monitoring.

Reduce CV rate (0–5 bpm if the child has PIE or 5–10 bpm if the child has poor compliance). Consider sedation.

Patient “fighting” the Life Pulse HFJV.

Patient may need comforting or sedation.

ET tube improperly positioned or occluded.

Ensure proper ET tube position. Correct plugging, occlusion, or excessive leaking. Reintubate if necessary.

Patient too large for Life Pulse setting.

Check Servo pressure. If ≥ 19 psi, patient may be too large for current Life Pulse settings. Decrease HFJV rate, PIP, and/or increase On-Time; increase CV support.

Humidifier cartridge/circuit leaking, kinked, or improperly installed.

Inspect humidifier cartridge/circuit for leaks, kinks, or poor connections, and correct condition. Change circuit if necessary.

Water bag empty or water supply line kinked or clamped (“LEVEL” also displayed).

Replace water bag if empty. Unkink or unclamp water supply line.

Cartridge not secure in cartridge housing.

Completely close and latch cartridge receptacle door.

Poor electrical connections between cartridge and Life Pulse.

Check cartridge latch and door to ensure they are secure. Reinstall cartridge.

Humidifier cartridge/circuit problem (“TEMP” may also be displayed).

Replace humidifier cartridge/circuit.

Cannot meet PIP

Circuit fault

Note: This guide highlights only the above alarms; the HFJV has many other alarms that the respiratory therapist might encounter. Refer to the manual for other alarms not listed here.

High-Frequency Oscillator Ventilation High-frequency oscillatory ventilation (HFOV) has been shown to reduce mortality and improve oxygenation in ARDS patients if used early in the disease process (the operative words being “used early”). This mode has been demonstrated

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in pediatric patients and is currently Food and Drug Administration (FDA) approved as an alternative to conventional ventilation. According to William Miles and his group, HFOV has been studied in infants comparing HFOV and conventional ventilation (CV), and results show improvement in oxygenation, reduced ventilator associated lung injury, decrease in mortality, and fewer mechanical ventilator days.12 HFOV has been studied extensively in infants and pediatrics, but it has not garnered much attention in the adult population with ARDS. In fact, there have been only a few randomized control studies as reported by Miles and others. The clinical trials that were reviewed did show that HFOV is a safe and effective mode of ventilation for the treatment of ARDS in adults.12 The use of high frequency ventilation in the PICU or NICU will depend on your unit medical protocol. Both HFJV and HFOV have been shown to be equally effective. One key fact to note: HFOV is a stand-alone mechanical ventilator, whereas HFJV must be used along with a conventional ventilator. HFOV Operations HFOV uses smaller tidal volumes and less variable airway pressure. This prevents the constant opening and closing of lung tissue seen with conventional ventilation. HFOV is designed to keep the alveoli in an open state, so as alveoli are opened and remain open, the gas moves around the lung tissue seeking to open as many closed alveoli as it can without overdistending those alveoli that are already opened. It may be difficult to visualize how HFOV really works; however, if you were to visualize what the lungs look like on the inside, it becomes easier. Imagine for a moment that you are looking at some alveoli and they are all shriveled up (a more technical term is “airless”). There are some alveoli that are open, but not fully inflated, and there are other alveoli that have too much air. If you add HFOV whose gas distribution mechanism is to ventilate at very fast rates and very small tidal volumes, the gas from HFOV is directed toward the underventilated alveoli, and over a period of time, those underventilated alveoli will respond and become inflated. On the other hand, those alveoli that are already overinflated will also respond to more gas, making these alveoli a prime target for pneumothoraces. The goal is to open more

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underinflated alveoli and avoid creating trauma to the already opened alveoli. That is how HFOV works. The research is clear: if HFOV is to work at all, you must have alveoli that are willing participants. Figures 8-11 and 8-12 depict the high-frequency oscillatory ventilator. As you may notice, there are no traditional knobs that are most familiar to us as respiratory therapists; yet the principle of ventilation and oxygenation is very clear. If you understand oxygenation as a function of mean airway pressure and ventilation as a function of amplitude, then you have got it. In conventional ventilation, gas delivery is active in inspiration and passive in exhalation, while in HFOV, gas delivery is active in both inspiration and exhalation. Higginson, in his description of highfrequency oscillatory ventilation, used the words of Cairo and Pilbeam to illustrate his point:13 Such a system will incorporate an electronic control circuit, or square-wave driver, which powers a linear drive motor. This motor consists of an electrical coil within a magnet, similar to a permanent magnet speaker. When a positive polarity is applied to the square-wave driver, the coil is driven forward. The coil is attached to a rubber bellows, or diaphragm, to create a piston.

Figure 8-11 HFOV front panel

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Figure 8-12 HFOV full view of the unit

When the coil moves forward, the piston moves toward the patient airway, creating the inspiratory phase. When the polarity becomes negative, the electrical coil and the attached piston are driven away from the patient, creating an active expiration. Here is a good way to remember how HFOV works: the more the pistons are displaced that create the oscillations (called amplitude), the bigger the tidal volumes delivered to the patient. Now that we have an understanding of how the oscillator works on the inside, let us discuss each component that simulates ventilator parameters.

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Oxygen 1. Oxygen blenders—Most HFOVs are accessorized with oxygen

blenders allowing you to control your fraction of inspired oxygen to the patient. 2. Mean airway pressure—This knob allows you to adjust the mean airway pressure in order to improve oxygenation. It is recommended to start your mean airway pressure at 4 to 5 cm H2O higher than the MAP of the conventional ventilator settings. For example, if your MAP on conventional ventilation is 25 cm H2O, then you might start with 29 to 30 cm H2O to achieve an open lung. It goes without saying that if there is evidence of hemodynamic instability, then it is prudent to reduce the MAP by 2 to 3 cm H2O or at least to the MAP on the conventional ventilator settings. Although the literature is rich with discussions regarding recruitment maneuvers, there should be a well-developed plan as to whether adding high levels of PEEP as a recruitment tool will benefit patients in your PICU. In my experience with using the HFOV in our PICU, recruitment maneuvers are not used often, if at all. This is not to say that recruitment maneuvers are never an option; however, it is recommended you tread carefully because your margin of error is less in infants and children. 3. Bias Flow—As with all ventilators, there must be a knob that adjusts the flow of gas delivered to the patient. The MAP knob is dependent on the bias flow: in fact, you must adjust your bias flow to adjust your MAP. Ventilation 1. Frequency—This is controlled by your hertz (Hz). One hertz is

equal to 60 breaths per minute; 15 Hz = 900 breaths per minute (pretty darn fast). The following are the recommended starting frequencies: Patient Infant Infant/children Older children

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Weight under 3 kg 3 kg or greater 30 kg or greater

Hz 15 10 to 15 6 to 10

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What you soon recognize is that the bigger the child, the lower the frequency, and the more the expected delivered volume of gas. Remember: a big change in frequency will have a dramatic change on both your amplitude as well as your MAP—think carefully when making a big frequency change. 2. Power—This controls chest excursion, which we call the wiggle factor. A good rule of thumb is to see the wiggle all the way to the belly button. That is a good chest wiggle. If you lose the wiggle, it could mean that you have a displaced endotracheal tube or an obstruction to gas flow. Your ability to hear breath sounds will be replaced with the sound of the piston on the ventilator, so you must adjust your hearing to that sound, the depth, and the pitch. If there are any changes, then you can determine that there has been a change in breath sound. Increase power and you increase wiggle; decrease power and you decrease wiggle. Some centers recommend a starting setting of “2.” Your PICU may have an established protocol. If not, then recommend to start with “2.” A change in power will affect your MAP, so you will have to readjust your MAP to keep it at the setting that is ordered. 3. Inspiratory time—This control is typically set at 33%, which means that 33% of the total time is spent in inspiration. Thirty-three percent would give you an I:E ratio of 1:2; 50% would give you an I:E ratio of 1:1. Table 8-6 displays these settings for easy reference, and Table 8-7 provides helpful tips on troubleshooting the oscillator. When a patient is placed on an oscillator, it is a big deal in more ways than one. Having to look at a child on HFOV can be unnerving, let alone having to work with the child as a patient on HFOV. Here are some things to consider while working with a child on HFOV: 1. The HFOV circuit is an elongated tubing made of highly inflex-

ible material. The tubing is designed to remain in a straight line to ensure that frequency of the sound waves have a clear path to the chest wall. Remember that sound waves cannot bend and they are not able to round the curve. Sound waves are familiar with one direction—straight.

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Table 8-6 HFOV Starting Settings Ventilation Patient

Weight

Hz

Frequency (rate) 1 Hertz = 60 breaths per minute

Infant Infants/children Older children

Under 3 kg 3 kg or greater 30 kg or greater

15 Hz 10 Hz to 15 Hz 6 Hz to 10 Hz

Amplitude/power

This determines the chest excursion. Set at “2” for most patients. Adjust this setting based on the amount of chest movement.

Inspiratory time These are very typical settings.

33% would give you and I:E ratio of 1:2. 50% would give you and I:E ratio of 1:1.

Tidal volume

Generates tidal volumes less than anatomical dead space

Oxygenation Oxygen

FiO2 to keep SaO2 greater than 90%. Focus on MAP to maintain oxygenation.

Mean airway pressure (MAP)

Start MAP at 4 to 5 cm H2O above the setting on CV. An increase in MAP can cause a decrease in hemodynamic stability—monitor change in blood pressure.

Bias flow

This is the flow of gas that is delivered to the patient. Starting setting of 20 LPM

Monitoring

Remember that HFOV is used as a lung protective strategy to promote improved gas exchange and minimize overdistention of lung tissue. Here is what you need: Patience while the infant’s lungs heal Pulse oximeters and or transcutaneous monitoring Arterial line to monitor blood gases

Weaning

Once there are signs of improvement based on improved blood gases, hemodynamic stability and overall patient appearance, then weaning can begin: MAP lower than 20 cm H2O Lower rate to minimize interference with spontaneous breathing A PIP of less than 16, a MAP of less than 8 cm H2O, FiO2 of 30% or less, and spontaneous breathing is evidence of an infant that should be transitioned to a short trial ET CPAP on CV. If infant does well with this trial, this is a good indication that NCPAP at 8 cm H2O will be tolerated.

Note: It is recommended to start HFOV as soon as possible to minimize the risk of volutrauma from conventional ventilation. Data provided by CareFusion, Yorba Linda, California.

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Table 8-7 Common Troubleshooting Techniques for the HFOV (Continues) Alarm

Possible Problem


Displayed mean airway pressure greater than 50 cm H20

Patient breathing spontaneously while at high mean airway pressures

Bias flow rate may be insufficient, readjust mean airway pressure using higher flow

Obstruction in the expiratory limb

Consider replacing the patient circuit.

Obstruction in pressure sensing line

Consider replacing the patient circuit.

Interference from a radio transmitter

Remove source of interference.

Patient spontaneously breathing

Bias flow rate may be insufficient, readjust mean airway pressure using higher flow.

Improper setting of thumbwheel switch

Change HFOV settings.

Obstruction in expiratory limb

Replace circuit.

Obstruction in pressure sense line

Replace circuit.

Patient circuit temperature rise

Check and correct circuit temperature.

Interference from a radio transmitter

Remove source of interference.


Bias flow rate may be insufficient, readjust mean airway pressure using higher flow.

Improper setting of thumbwheel switch

Change setting.

Improper setting of mean airway pressure or flowmeter

Change setting.

Patient circuit temperature drop

Check and correct circuit temperature.

Improper setting of the mean airway pressure limit

Change setting.

Leak in patient circuit or humidifier

Eliminate leak or replace circuit.

Cap diaphragm leak

Replace cap diaphragm.

Interference from a radio

Remove source of interference

Power setting too low and change is less than 6 cm H20

Adjust setting for desired delta P.

Oscillator not centered

Readjust oscillator centering.

Oscillator failure

Call SensorMedics service.

Input pressure less than 30 psi, either from blender or cooling air

Check input gas lines.

Input filter needs replacement

Replace filters.

Flow restriction in gas supply lines

Replace supply lines.

Internal leak


Displayed mean airway pressure greater than set maximum mean airway pressure thumbwheel alarm

Displayed mean airway pressure less than set maximum mean airway pressure thumbwheel alarm

Oscillator stopped with no other alarm occurring

Source gas low alarm

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Possible Problem


Battery low alarm

Battery voltage less than optimal

Replace battery.

Battery disconnected

Reconnect battery.

High pitched alarm, no indicator light

The electronic fan stopped


Reset/power failure

AC power removed from system or main power interruption

Check line cord. If OK, check other equipment on same outlet. If other equipment OK, could be internal fault.

Internal power supply failure

Apply power to system, press and hold “Reset” to establish mean airway pressure, then press Stop/Start switch. (This starts oscillator after correcting problem.) Call SensorMedics service.

Failure to meet patient circuit calibration

Eliminate leak or replace patient circuit.

Improper flowmeter setting

Set flowmeter to 20 LPM, sighting on center of ball.

Open water trap stopcock

Close water trap stopcock.

Internal leak or maladjustment

Call SensorMedic service.

Water collecting at mean airway pressure adjust valve

Adjust circuit height for better drainage.


Bias flow may be insufficient, readjust mean airway pressure using higher flow.

Worn or defective cap diaphragm

Replace cap diaphragms.

Internal failure


Mean airway pressure jumping by more than 5 cm H20 when trying to adjust with mean airway pressure adjust valve

Worn or improperly seated cap diaphragm

Replace cap diaphragms.

Internal failure


Unable to center

Extremely high delta P

Normal behavior at extremely high delta P.

Cooling gas leak or blockage

Check cooling gas supply and filter cartridge, replace if necessary

Internal failure


Mean airway pressure unstable—jumps by 2–3 cm H20

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Leak in patient circuit or humidifier connections

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Possible Problem


Oscillator makes a squeaking sound

Limit valve set too low

Readjust limit valve to slightly higher setting

Cap diaphragm defective

Replace cap diaphragm

This guide only highlights the above alarms; the HFOV has many more alarms that the respiratory therapist might encounter. Refer to the manual for other alarms not listed here. Data provided by CareFusion, Yorba Linda, California.

2. When initiating HFOV, make sure that the child is on a hard

surface. I recall a situation several years ago when a colleague of mine was called to the PICU by a new therapist who was asking for help in troubleshooting the oscillator. It had been a very tense moment for this new therapist, exhausting every available brain cell to troubleshoot this piece of equipment. Upon arrival to the PICU, my colleague was able to detect the problem. It was the bed! Yes, the patient was lying on a bed designed to prevent pressure sores, and thus the bed was the problem. It was too soft and had too much give. Sound waves must have something hard to bounce off. Once the bed was changed, oscillation started. 3. Before starting HFOV, it is strongly recommended to suction the patient thoroughly because breaking the circuit for routine suctioning is discouraged. The literature supports the use of in-line suction catheters as the standard of care because they minimize the amount of derecruitment required. Very important: if you must suction, get help. It is better to have two caregivers than just one. 4. Most patients on HFOV will have a properly placed and working arterial line so monitoring arterial blood gases should never be a problem. If, on the other hand, the arterial line is not available, then noninvasive monitoring with pulse oximetry and either an end-tidal CO2 monitor or transcutaneous monitor will work perfectly. Monitoring of children on HFOV requires vigilance on the part of all caregivers, especially the respiratory therapist.

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Summary

This chapter discusses the four most common air leaks seen in both neonatal and pediatric intensive care units. ✔✔ Air leak syndrome occurs most often in infants diagnosed with infant respiratory distress syndrome, meconium aspiration syndrome, and transient tachypnea of the newborn. ✔✔ Infants with these diagnoses are at high risk of pneumothorax secondary to high transpulmonary pressure associated with poor lung compliance and high airway resistance. ✔✔ Older children with chronic lung diseases are also at risk for pneumothoraces. ✔✔ Any child who has a sudden change in hemodynamic stability and is on a mechanical ventilator warrants high suspicion of the potential for a pulmonary air leak. ✔✔ Although pneumothorax, pneumomediastinum, and pneumopericardium may have different entry points, ultimately the treatment is the same—needle aspiration with or without chest tube insertion. The size of the air leakage will determine the management strategy. In contrast, PIE is free air that travels throughout the tissues of the lungs and is generally trapped in place. ✔✔ PIE appears as diffuse hazy opacification of the lungs consistent with the lack of surfactant. PIE is typically seen in low birth weight babies and is caused by prolonged use of positive pressure ventilation. ✔✔ PIE can cause worsening of arterial blood gases. Lung protective strategies should be employed to decrease peak inspiratory pressures, lower lung volumes, lower oxygen requirements, and lower inspiratory times. References 1. Meberg, A., Greve-Isdahl, M., & Heier, C. (2007, September 20). Pulmonary air-leakage in newborn infants. Tidsskr Nor Laegeforen, 127 (18), 2371–2373. 2. American Academy of Pediatrics and American College of Emergency Physicians. (2004). The pediatric emergency medicine resource (4th ed.) Sudbury, MA: Jones and Bartlett Publishers.

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3. Wilkins, R., Stoller, J., & Scanlan, C. (2003). Egan’s fundamentals of respiratory care (8th ed.). St. Louis, MO: MosbyYearbook. 4. Whitaker, Kent. (2001). Comprehensive perinatal and pediatric respiratory care (3rd ed.) Albany, NY: Delmar Thomson. 5. Mohamed, I., Yi-Horng, L., Yamout, S., Fakir, S., & Reynolds, A. (2007). Ultrasound guided percutaneous relief of tension pneumomediastinum in a 1-day-old newborn. Archives of Diseases in Childhood—Fetal and Neonatal Edition, 92, F458; doi:10.1136/adc.2006.114322. 6. Berk, D., & Varich, L. (2005). Localized persistent pulmonary interstitial emphysema in a preterm infant in the absence of mechanical ventilation. Pediatric Radiology, 35, 1243–1245. 7. Donnelly, L., Lucaya, J., Ozelame, V., Frush, D., Strouse, P., Sumner, T., et al. (2003). CT findings and temporal course of persistent pulmonary interstitial emphysema in neonates: A multiinstitutional study. American Journal of Roentgenology, 180, 1129–1133. 8. Kacmarek, R., Dimas, S., & Mack, C. (2005). The essentials of respiratory care (4th ed.). St. Louis, MO: Mosby Elsevier. 9. Bunnell, B. (1994, December 8). Life Pulse high-frequency jet ventilator reference manual. 10. Stocker, J., & Madewell, J. (1977). Persistent interstitial pulmonary emphysema: Another complication of the respiratory distress syndrome. Pediatrics, 59, 847–857. 11. Keszler, M., Donn, S., & Bucciaerelli, R. (1991). Multicenter controlled trial comparing high-frequency jet ventilation and conventional mechanical ventilation in newborn infants with pulmonary interstitial emphysema. Journal of Pediatrics, 119, 85–93. 12. Miles, W., & Hylton, J. (2005, August). The challenges of high frequency oscillatory ventilation. RT For Decision Makers in Respiratory Care. Retrieved March 21, 2008, from http://www.rtmagazine.com/issues/articles/2005–08_03.asp 13. Higginson, R. J. (2003). High frequency oscillatory ventilation. Internet Journal of Emergency and Intensive Care Medicine, 6 (2). Retrieved March 10, 2008, from http://www.ispub.com/ostia/index.php?xmlFilePath=journals/ijeicm/ vol6n2/hfov.xml

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Chapter

9

Congenital Heart Disease Chapter Outline DEFINE • Define four common cyanotic heart diseases Tetralogy of Fallot Transposition of the great vessels Tricuspid atresia Total anomalous pulmonary venous return • Define four common noncyanotic heart diseases: Atrial septal defect Ventricular septal defect Patent ductus arteriosus Coarctation of the aorta DESCRIBE • Describe symptoms for common cyanotic heart diseases: Tetralogy of Fallot Transposition of the great vessels Tricuspid atresia Total anomalous pulmonary venous return • Describe symptoms for common noncyanotic heart diseases: Atrial septal defect Ventricular septal defect Patent ductus arteriosus Coarctation of the aorta

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DISTINGUISH • Congestive heart failure • Acquired heart disease RESEARCH • Relevant research on treatment strategies for patients with cardiac lesions TREATMENT • Treatment options for patients with cardiac lesions

Key Terms Atrial septal defect Coarctation of the aorta Congestive heart failure Cyanotic heart disease Hyperoxia test Mechanical ventilator Noncyanotic heart disease Patent ductus arteriosus Prostaglandin E1 Tetralogy of Fallot Total anomalous pulmonary venous return Transposition of the great vessels Tricuspid atresia Ventricular septal defect

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Chapter 9 Congenital Heart Disease

INTRODUCTION

It is hard to imagine an infant with heart disease, but 8 out of every 1000 infants born each year have a heart defect.1 Respiratory therapists are very familiar with the term congestive heart failure (CHF). This condition, which occurs frequently in adults, similarly occurs in children with an underlying cardiac defect. This chapter will describe some of the common cyanotic and noncyanotic heart lesions that occur in children. Some of these cardiac lesions will in fact lead to CHF. A classic sign of cyanotic heart disease is appearance of this bluish discoloration to the skin, whereas noncyanotic heart disease does not present with significant cyanosis. Normal oxygen saturation on the right side of the heart is approximately 70–75%, whereas on the left side, it is 95–98%.2 In many instances, a baby with a cyanotic heart lesion is dependent on some type of shunt. One example is the ductus arteriosus, which shunts blood between the aorta and pulmonary artery and bypasses the lungs. Closure of this shunt might mean the death of an infant. This is very important, depending on the type of heart lesion. On the other hand, noncyanotic lesions remain asymptomatic, and children become adults and do not display signs of cardiac insufficiency for many years, if at all. Although there are many cardiac lesions discussed in the literature, this chapter will highlight four common cyanotic heart diseases, followed by a discussion of four common noncyanotic heart diseases. The study of heart disease is fascinating. The American Heart Association estimates that there are approximately 36,000 babies born each year with some type of congenital heart disease, and at least 9 out of every 1000 infants born each year have a heart defect.2 To discuss cardiac anomalies in infants and children, it is necessary to describe what happens before birth. Figure 9-1 illustrates the normal fetal circulation, which is the lifeline between the fetus and mother. The placenta circulation provides the exchange of nutrients that supports the growth of the fetus until delivery. Additionally, the placenta is the conduit through which the growing baby is able to rid itself of body waste. With the use of ultrasound technology, it has become easy to detect a heart abnormality in the womb. This provides the medical team with real-time information about

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Aortic arch

189

Ductus arteriosis

Superior vena cava

Pulmonary vein

Right pulmonary artery

Left pulmonary artery

Right pulmonary veins

Left pulmonary veins

Foramen ovale

Left atrium

Right atrium Right ventricle

Left ventricle

Inferior vena cava Descending aorta Placenta Figure 9-1 Normal fetal circulation

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the formation of the heart structures. Determining heart abnormalities prior to birth helps the team to develop a plan to manage the infant at the time of birth. Understanding this concept is urgent because the interruption of placenta circulation at birth begins a cascade of events that allows the infant’s body to switch to adult circulation and begin breathing on his or her own. This switch must be done within minutes of the birth. Adult circulation is built around the body’s systemic pressures being higher than its pulmonary pressure. This causes a functional closure of the three uterine shunts (see Figure 9-1 for an illustration of the normal fetal circulation). The shunts are the ductus arteriosus, the foramen ovale, and the ductus venosus (see Table 9-1). Within hours to a week after birth, all shunts are functionally closed and the infant’s systemic circulation functions in accordance with that of the adult system.3,4 If a shunt fails to close after birth, there is an examination of the causes and classification of the heart defect. As a respiratory therapist, having an excellent understanding of these diseases can help you develop a plan to provide respiratory support to this infant or child, should he or she require it.

Table 9-1 Uterine Shunt Closures

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Shunt Type

Before Birth

At Birth

Ductus arteriosus

This vessel allows blood to bypass the lungs and creates a shunt between the pulmonary artery directly to the aorta.

Ductus arteriosus closes, forcing blood to go through the pulmonary vascular bed to pick up and exchange gases there. This begins upon an infant’s first breath; it happens as a result of an increase in the partial pressure of oxygen.

Foramen ovale

This is an opening between the right and left atrium. Most blood shunts from the right atrium through this opening to the left atrium.

The increase pressure in the left atrium will cause the one-way valve on the atrial surface of the foramen ovale to remain closed, preventing blood from going back into the right atrium. Blood will now flow from the right atrium to the right ventricle.

Ductus venosus

Blood flows from the inferior vena cava. Blood enters the abdominal cavity, and 50% is directed to the umbilical veins into the liver.

Ductus venosus closes due to a lack of blood flow. When the umbilical cord is clamped, this stops blood flow to the umbilical vein and artery.

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The American Heart Association reports that there are about 1 million Americans living with cardiovascular defects.2 It is not expected that the role of the respiratory therapist will extend to the operating room. Yet it is a good idea to know what actually happens in the operating room with some of the more common cardiac defects. This chapter deals primarily with describing the condition, how the condition presents, and the most commonly used treatments. DEFINE

Cyanotic Heart Diseases Tetralogy of Fallot Tetralogy of Fallot accounts for four types of heart lesions present at birth. It occurs in approximately 5 out of 10,000 infants.1,2,3,5 It is considered a cyanotic heart defect due to the low level of oxygen in the blood. Recall from Table 9-1 that there is a reduced blood flow to the pulmonary system due to uterine shunt closures. Blood bypasses the lungs, where it would normally pick up fresh oxygen-rich blood and send it on to the body; this is compatible with the blue discoloration of the skin. Initial presentation of a baby with tetralogy of Fallot may not reveal cyanosis, but he or she may develop these horrific cyanotic episodes later. This has been referred to as a “TET spell.” This defect, as pictured in Figure 9-2, shows the defects associated with tetralogy of Fallot. The defect is a combination of (1) a ventricular septal defect (VSD), (2) a narrowing of the pulmonary outflow tract, (3) an aorta that arises from both ventricles, and (4) a thick muscular wall of the right ventricle.1,2,3,5 Transposition of the Great Vessels Although transposition of the great vessels has a low rate of incidence in the general population, it is quite common in neonates, with an overall incident of 40 per 100,000 births annually.5 This condition occurs more often in infants born to a diabetic mother.5 This congenital defect connects the two main arteries to the wrong heart chambers. In other words, the aorta is connected to the right ventricle and the pulmonary artery is connected to the left ventricle. Fortunately, most babies with this defect also have some other cardiac defect like an atrial septal defect (ASD; see Figure 9-3) or

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NORMAL

Pulmonary valve

Ventricular septum Left ventricle

Right ventricle

DEFECT

Ventricular septal defect

Stenotic pulmonary valve Figure 9-2 Tetralogy of Fallot

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NORMAL Left atrium Atrial septum Right atrium

DEFECT

Atrial septal defect

Figure 9-3 ASD

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ventricular septal defect (VSD; see Figure 9-4), which allows for the mixing of blood, so the body gets some oxygen although it maybe low in concentration. Transposition of the great vessels, of which there are

NORMAL

Ventricular septum

Right ventricle

DEFECT


Figure 9-4 VSD

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two types, D and L, require immediate surgery usually within the first week of life. Type L (the aorta may be anterior and to the left of the pulmonary artery) appears to be less severe than Type D (the aorta is anterior and to the right of the pulmonary artery). Both are considered life-threatening, but Type D is more likely to require a surgical intervention within a few weeks of the birth. Additionally, what is interesting about this condition is that it affects more males than females—by an astounding 3 to 1—and accounts for about 5% of all cases of congenital heart conditions.6 Gordon Avery et al. report that transposition of the great vessels is by far the most common life-threatening condition for a neonate during the first few weeks of life.4,7 Figure 9-5 illustrates transposition of the great vessels. Tricuspid Atresia Recall from anatomy class the description of the tricuspid valve. This valve is designed to keep blood moving in the right direction. The tricuspid valve is a three-leaf valve that is positioned between the right atrium and right ventricle; however, in tricuspid atresia, the valve is either missing or broken. This becomes a blockage that prevents blood flow from the right atrium to the right ventricle, through the pulmonary trunk, and on to the lungs. This accounts for why these babies are blue at birth. The heart is not able to pump blood to the lungs, where it picks up oxygen, and then sends it to the rest of the body. Like transposition of the great vessels, this condition is serious, and the infant will need mechanical ventilation until surgery can be done. Rao suggests that 1 in every 10,000 live births is affected by tricuspid atresia (see Figure 9-6) in the United States, and the incidence rates do not vary much by race or gender.8,9 Total Anomalous Pulmonary Venous Return (TAPVR) This is an interesting heart disease in which the veins that drain blood from the lungs to the heart are not attached to the left atrium. Let’s go back to our heart anatomy for a moment. Blood flows as follows: it travels from the upper and lower body through the superior and inferior vena cava Æ to the right atrium Æ through the tricuspid valve Æ to the right ventricle Æ to the pulmonary trunk by way of the pulmonary arteries Æ through the

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NORMAL

Aorta

Right atrium

Pulmonary artery Left atrium

Left ventricle

Right ventricle

Aorta

DEFECT

Pulmonary artery Atrial septal defect Left ventricle Right ventricle Figure 9-5 TGV

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NORMAL Atrial septum Right atrium Pulmonary valve

Left atrium Left ventricle Right ventricle

Tricuspid valve

DEFECT

Atrial septal defect Absent tricuspid valve


Small right ventricle

Figure 9-6 Triscupid atresia

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lungs Æ to the left atrium via the pulmonary veins Æ through the mitral valve Æ to the left ventricle Æ through the aorta Æ to the body. The pulmonary veins are supposed to take oxygen-rich blood to the left ventricle, which would ultimately pump this blood to the body; however, in TAPVR, the veins are missing, and blood now is being redirected back to the right atrium. The end result is that there is no oxygen-rich blood going to the body. Therefore, this condition is life threatening, requiring immediate attention, and possibly surgery early on. There are three types of total anomalous pulmonary venous return (TAPVR; see Figure 9-7) that presents in infants: 1. Supracardiac—the most common type, in which the pulmonary

veins are connected by a vessel to the superior vena cava

2. Infracardiac—a less common type, in which the pulmonary veins

are connected directly to the inferior vena cava

3. Intracardiac—an even less common type, in which the pulmonary

veins are connected directly to the right atrium5,10

As long as there is no obstruction along any segment of the pulmonary trunk, it is possible that the child will be asymptomatic. On the other hand, if there is any type of blockage, then surgery is required immediately.4,10 Noncyanotic Heart Diseases Atrial Septal Defect (ASD) Atrial septal defect is characterized as a hole at some point between the right and left atria. In many of the congenital cardiac defects, this is a good thing, because having this opening allows for the mixing of deoxygenated blood with oxygenated blood, so the body can receive some oxygen, even if the concentration of oxygen is lower than expected. In and of itself, ASD accounts for only up to 10% of all cases with severe symptoms and is found more in females than males.4,5,10 A small ASD generally presents no significant problems in infancy; only a moderate to large ASD may cause concern. Usually this concern is demonstrated when a child has a large left-toright shunt that inhibits growth and promotes congestive heart failure. In ASD cases, surgery is appropriate. However, Avery et al. suggest that

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NORMAL Right pulmonary vein

Left pulmonary vein Left atrium

Right atrium

DEFECT Right pulmonary vein Atrial septal defect

Abnormal pulmonary vein

Left pulmonary vein

Figure 9-7 TAPVR

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surgery for an isolated ASD in early infancy should be taken with great caution.4 Ventricular Septal Defect (VSD) VSD can be described as one or multiple holes in the wall that separates the right and left ventricles. It is one of the most common congenital heart defects observed. Approximately 21% of all children have a VSD.4,5,10 Avery et al. state that VSD is the most common lesion and is usually seen within the first 7 to 30 days after birth.4 If the defect is small in the first year of life, it self-closes and the infant presents with no symptoms. However, if a VSD is large, then too much blood is pumped to the lungs, causing a serious backup in the lungs, leading to congestive heart failure. In instances of a large VSD in an infant during the first 12 months of life, surgery will always be the solution. Patent Ductus Arteriosus (PDA) The ductus arteriosus is one of the three uterine shunts that allow blood to bypass the lungs. This shunt connects the aorta to the pulmonary artery. This conduit allows some oxygen-rich blood from the mother to the fetus via the placenta. At or soon after birth, this shunt begins to close. Most literature suggests that the ductus arteriosus functionally closes within hours to weeks after an infant is born.3,4 Patent ductus arteriosus (patent is Latin for “open”), an abnormal blood flow between the aorta and the pulmonary artery that allows blood flow to bypass the lungs, affects about 3000 infants in the United States each year, again affecting more females than males.2,4,5,10,11 To appreciate this condition, let us describe what happens in utero before the baby is born. In utero, the placenta acts as the organ of respiration, as well as nutrition and excretory function, between mother and fetus.4 In order to accomplish this, the fetus’s blood circulation system must be a low pressure system so as not to compete with the high pressure system of the mother. Fitzmaurice and Gerardi, in their chapter from the American Academy of Pediatrics’ APLS: The Pediatric Emergency Medicine Resource, describe it as follows: In the normal fetal circulation, oxygenated blood returns from the placenta via the ductus venosus, mixing with some systemic

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venous return blood in the inferior vena cava. This oxygenated blood partially mixes with deoxygenate systemic venous blood in the right atrium, but oxygenated blood is preferentially shunted through the foramen ovale to the left atrium and left ventricle where the most oxygenated blood is pumped to the cerebral and coronary circulations … (p. 109)1 The birthing process is complex. When the ductus arteriosus remains open after the child is born, it can cause serious problems. PDA, referred to as a left-to-right shunt, is seen in premature infants experiencing infant respiratory distress syndrome. It can also be seen in isolated cases. Avery et al. indicate that the prevalence of babies born with a PDA without infant respiratory distress syndrome is about 3.9%.4 Avery et al. further state that this defect is more common in females and presents most often in combination with other congenital heart lesions.4 While working in a neonatal intensive unit, you will likely see PDA in very tiny infants on and off mechanical ventilators. Let me give you an example. Clinical Note Imagine that you are at a patient’s bedside, doing your routine ventilator check, when you hear an alarm. You look up at the monitor, and you are alarmed to find that the pulse oximeter is reading 65% oxygen saturation. You say in your head, this cannot be true. You immediately begin a thorough assessment of the baby and find the child still connected to the ventilator, breath sounds equal bilateral, color looks okay, or at least not cyanotic, so you proceed to turn up the FiO2 on the ventilator. Of course the moment you have documented the FiO2 change, the child’s saturation is now 100%, which requires you to make another FiO2 change. You think to yourself, what is going on? Most of us do not think anymore because we recognize this as the potential sign of a PDA. Although it can be frightening to see saturations drop down in the 40s, you breathe a sigh of relief, because there is a very good reason that your palms are sweaty. After a review of the chart, you learn that the child has been treated twice with a medication called indomethacin (in the treatment section, we will discuss indomethacin vs. NeoProfen) to facilitate closure of the patent ductus arteriosus, which has subsequently failed. The baby is scheduled for surgery to have the patent ductus arteriosus permanently closed.

Coarctation of the Aorta This condition is the narrowing of the aorta. The aorta is the very large artery that allows for the conduction of blood

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to the rest of the body. When there is a narrowing at any point along the aorta, it will cause a significant increase in systemic pressure. This is seen as a rise in blood pressure to the upper extremities; however, the blood pressure is low in the lower extremities. This lesion is significant in about 1 out of 10,000 people, most of whom are children and adults under 40 years of age.5,10 Avery et al. indicate that coarctation of the aorta accounts for 6% of newborns with heart disease and is the most common cause of congestive heart failure in the neonate.4 The cause is not known; the current thought is that it happens most often in people who have other genetic abnormalities. Understanding coarctation of the aorta is important even though there may be no symptoms. High blood pressure, a symptom that causes devastation to the body, can damage other organs in the body. There is reason for concern when children and young adults present with high blood pressure. Keep in mind that blood pressure in newborns is determined by age and weight.3 DESCRIBE

Congenital heart disease has been described as cyanotic lesions that result either in a structural defect or flow anomalies whereas noncyanotic lesions can be the result of congestive heart failure with or without a murmur. Noncyanotic lesions can be further understood as obstructive lesions with left-to-right shunt with an increase in blood flow to the pulmonary circulation.1 Cyanotic Heart Diseases Tetralogy of Fallot has been characterized as the congenital heart defect that is seen most often in patients with chromosomal abnormalities like Down syndrome. Its defining characteristics are the classic “TET spells” observed from a crying infant. Symptoms of Tetralogy of Fallot • Inability to feed well • Failure to thrive

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Inadequate or delayed growth development Fainting and sometimes loss of consciousness Clubbed fingers Squatting during a TET spell Congestive heart failure is rare in this condition Sudden death

Transposition of the great vessels (TGV) can be described as a lifethreatening event that requires another heart defect for survival. Ventricular septal defect is often detected in patients with TGV. This condition is usually suspected hours or days following the closing of the PDA and the foramen ovale. Once these uterine shunts begin to close, worsening respiratory distress with profound cyanosis is evident, requiring immediate action to construct an opening between the pulmonary artery and the aorta. Drug therapy with prostaglandin E1 is used as a temporary measure to keep the ductus arteriosus open until permanent surgery can be done. Intensive monitoring of symptoms is necessary until permanent relief is completed. Symptoms of TGV • • • •

Cyanosis Shortness of breath Inadequate nutritional intake Clubbed fingers or toes, which might indicate chronic or possible heart failure

Tricuspid atresia has been described as either a missing tricuspid valve or a tricuspid valve that does not open. In either case, the result is the presentation of an ASD, VSD, cyanosis, or decreased pulmonary blood flow. Infants and children are usually symptomatic due to the decreased pulmonary blood flow, and they require some type of surgical intervention immediately to improve pulmonary blood flow. In most instances, the creation of a patent ductus arteriosus using a modified Blalock-Taussig shunt connects the pulmonary artery to the aorta. This shunt directs more blood to the pulmonary circulation until a permanent surgical procedure is performed to correct this defect.

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Symptoms of Tricuspid Atresia • Shortness of breath • Severe cyanosis • Tires easily (less energy to crawl, walk, run, or play; uses accessory muscles more often) • Congestive heart failure • Failure to thrive • Tachypnea Total anomalous pulmonary venous return (TAPVR) is characterized by pulmonary veins that are abnormal in structure and unable to carry oxygen-rich blood from the lungs to the left atrium. This defect demonstrates a continuous mixing of oxygen-rich blood with deoxygenated blood. In order for the body to receive some oxygenated blood, blood is shunted through a hole in the atrial wall. Most children with TAPVR will have varying degrees of cyanosis, and if there is no obstruction to blood flow, most children will remain symptom free. On the other hand, if there is an obstruction at any point during the course of the blood flow, surgical intervention may be necessary. Symptoms of TAPVR • Varying degree of cyanosis—depends on the degree of obstruction to blood flow • Inadequate food intake • Tachypnea • Frequent respiratory infection • Lethargy Noncyanotic Heart Diseases Atrial septal defect (ASD) is a hole in the wall of the heart muscle that separates the right atrium from the left atrium. It is characterized by a left-to-right shunt. The hole between the atrium allows oxygen-rich blood to move from the lungs to the right atrium, then to the right ventricle, which in fact creates a bypass of blood going to the body. There are three variations of ASD:

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1. Ostium primum defect—a hole located in the lower part of the

atrial septum

2. Ostium secundum defect—a hole near the center of the atrial sep-

tum

3. Sinus venosus defect—a hole near one of the two places where the

vena cava enters the right atrium10

Infants and children with ASDs may be asymptomatic for many years. This is due in part to the size of the ASD. The greater the opening between the wall of the atrium, the more severe the symptoms will be. Symptomatic children will require close monitoring and maybe surgical repair. Symptoms of ASD • • • •

Frequent respiratory infections Shortness of breath Heart palpitations Dyspnea on exertion

Ventricular septal defect (VSD) can occur at varying places along the septal wall of the ventricles. Small ventricle septal defects are usually managed with medication, whereas large VSDs require surgical repair. The larger the VSD and the more blood that is shunted to the pulmonary circulation, the more likely the child will suffer from congestive heart failure. Of equal concern is that an increase in blood to the lungs with abnormally high pressure can result in pulmonary hypertension, which may in fact render the heart unable to pump effectively. Symptomatic VSDs require careful monitoring and possibly surgical intervention. Symptoms of VSD • • • • • • •

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Shortness of breath Tachypnea Labored breathing Retractions Failure to thrive Pale complexion Pounding heartbeat

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• Diaphoresis (excessive sweating) • Frequent respiratory infections Patent ductus arteriosus (PDA) is a common presentation in premature infants with respiratory distress syndrome. PDAs are also common in other more life-threatening congenital heart diseases, particularly in transposition of the great vessels. It is desirable that a PDA be present to facilitate some mixed oxygen blood to circulate to the body. Small PDAs may be asymptomatic and may often be described as a heart murmur heard with a stethoscope. Large PDAs that are symptomatic may add stress on the heart, resulting in excessive blood flow to the pulmonary circulation. Infants with symptoms of PDA must be closely monitored for signs of increasing respiratory distress. Symptoms of PDA • • • • • • • • •

Shortness of breath Tachypnea Labored breathing Retractions Failure to thrive Pale skin color Pounding heartbeat Diaphoresis Heart infections

Coarctation of the aorta is described as a narrowing of portions of the aorta. Although linked to other genetic disorders, it is typically discovered in young children during their first physical examination. Symptoms of coarctation of the aorta are highly dependent on how much blood flows through the aorta. Mild symptoms may not be evident until later in life, whereas severe symptoms may be evident in the very young child. Symptoms of Coarctation of the Aorta • • • •

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Shortness of breath Dizziness or fainting Pounding headache Chest pain

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Cold feet and legs Leg cramps with exercise Hypertension with exercise Decreased ability to exercise

DISTINGUISH

In the clinical management of congenital heart diseases, it becomes necessary to make a distinction among the types of cardiac lesions. Equally important is to determine whether the cardiac lesion is a result of an external condition or the by-product of an external condition. Congestive heart failure and a few of the acquired heart diseases will be discussed here for your consideration. Congestive Heart Failure The American Academy of Pediatrics (2006) reports that for most infants and children, diagnosis of congestive heart failure (CHF) is related to congenital heart disease.1 A child or an infant who has a congenital heart lesion is more likely to acquire CHF as a by-product of their congenital heart defect. Kacmarek et al. report that “approximately 8% of congenital defects are associated with specific chromosomal abnormalities (e.g., trisomy 21 or trisomy 13).”12 It has been described as an unusual occurrence to have an infant present with CHF at birth, but it does happen. Most babies who have right heart failure can be attributed to some type of obstruction. This obstruction could be related to the flow of blood from one side of the heart to the other. In these instances, the baby needs some type of hole between either atria or ventricles that will allow for the mixing of deoxygenated blood with oxygenated blood.4 The bottom line is that any number of congenital cardiac defects can predispose a baby to congestive heart failure. Rapid assessment of the symptoms of CHF in infants and children makes the difference between success and failure in the treatment of a child with CHF. Symptoms of Congestive Heart Failure • An enlarged heart on chest radiograph • Vomiting

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Pulmonary infections Diaphoresis Tachypnea Grunting/retractions Hypoxemia Peripheral edema Irritability Shock (late sign)

Acquired Heart Disease Acquired heart diseases are conditions that result from some type of infection that causes inflammation to the various areas of the heart. These conditions are typically not congenital but acquired. There are a number of conditions; however, this guide will discuss only the following handful. Myocarditis, Pericarditis, Bacterial Endocarditis, and Cardiomyopathy Myocarditis is the inflammation of the myocardium from an infection or an abnormal immune response related to an infection. Acute rheumatic fever, a common type of myocarditis, is seen most often in children 6 to 12 years with an untreated streptococcal infection.1 Signs of myocarditis can be sweating with feeding, irritability, lethargy, shock, fever, muffled heart sounds, dysrhythmias, and heart murmurs. Pericarditis is the inflammation of the pericardial sac with increased amounts of pericardial fluid. This increase in fluid volume can cause a decrease in stroke volume. A sudden increase in fluid in the pericardial sac can cause a restriction on the movement of the heart, which can result in hypotension and cardiac tamponade. Pericarditis is caused most often by a bacterial infection such as the pneumococci, staphylococci, and Haemophilus influenzae. Pericarditis has also been attributed to viral infections such as the Coxsackie virus. Signs of pericarditis are chest pain, severe respiratory distress, increased work of breathing, poor perfusion, and cardiac arrest.1 Bacterial endocarditis is the inflammation of the endothelial lining of the heart, more specifically as it involves the heart valves. It is caused

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by gram-positive cocci, of which Staphylococcus aureus and Streptococcus pneumoniae seem to be the most prevalent. Recent history of cardiac surgery involving the replacement or implantation of artificial valves is the best indication of bacterial endocarditis.1 Cardiomyopathy is the enlargement of the heart muscles in otherwise normal appearing, healthy children. It is characterized by a sudden collapse, syncope, and systole heart murmur. It can cause congestive heart failure. Signs of cardiomyopathy include increased work of breathing, failure to thrive, sudden cardiac arrest, family history of sudden death, heart murmur, and syncope with exercise.1 RESEARCH

The amount of research in the area of congenital heart disease is overwhelming. There is no shortage of good research dating back to the early 1950s, when the echocardiogram became the standard used to diagnose a cardiac defect. Fitzmaurice and Gerardi report 5 to 8 cases of congenital heart disease per 1000 live births.1 Hoffman and Kaplan looked at the incidence of congenital heart disease from 62 studies published after 1955 to understand why the numbers varied from one study to another.6 Their study, published in the Journal of American College of Cardiology, reports that the severity of the congenital heart disease and the sophistication of the medical system to detect the condition had a significant impact on what was reported versus what was not reported. The Hoffman and Kaplan study concludes that for patients with severe congenital heart disease who required medical attention, the incidence is 2.5 to 3 per 1,000 live births, whereas those with the moderate-severe form of congenital heart disease account for 3 per 1,000 live births.6 Hoffman and Kaplan’s research indicates that if every major form of congenital heart diseases were reported regardless of how small, the incidence would be as high as 75 per 1,000 live births.6 They looked at only those conditions serious enough to require cardiology consultation. At the time of this writing, the literature review identified 35 cardiac defects currently seen in patients.2 It is not the intent of this guide to review all 35, but to review the ones most commonly seen in the neonatal and pediatric intensive care units. Most respiratory therapists will

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encounter a patient with a cardiac defect when the defect has seriously compromised the patient’s respiratory status and positive pressure ventilation is required. Whitaker makes two very important points when it comes to ventilating these types of patients. His points are that the various cardiac diseases impact the pulmonary system in different ways, because they (1) either reduce pulmonary blood flow to the lungs or (2) they increase pulmonary blood flow to the lungs.3 Table 9-2 illustrates an example of cyanotic and noncyanotic cardiac defects on the pulmonary system and the subsequent ventilator strategies. Because respiratory therapists are considered the experts in ventilator management, it is to our benefit to really know the cardiac defects that require ventilatory support. If you are in the NICU or PICU, your strategy should be as follows: 1. Ventilate with the least amount of pressure as possible. 2. Use a ventilator modality that allows the baby to control his or her

ventilation. For example, a cyanotic heart disease might require you to recommend changing the respiratory rate versus the inspiratory pressure where a noncyanotic heart disease might require you to change the inspiratory pressure instead of the respiratory rate. A quick understanding of the cardiac condition will make it easy to understand how you would manage your mechanical ventilator. 3. Ensure adequate oxygenation, and wean oxygen whenever possible. Table 9-2 Mechanical Ventilator Strategies in Patients with Cardiac Defects Cardiac Defect

Pulmonary Blood Flow

Lung Compliance

Ventilator Strategy

Oxygen Use

Tetralogy of Fallot

Reduced blood flow

Increase lung compliance

Change frequency of ventilation instead of inspiratory pressure; goal is to keep MAP low and still meet patient’s inspiratory need

Caution use of oxygen—a high PaO2 may close a necessary PDA

VSD

Increased blood flow

Decreased lung compliance

High ventilatory pressures and PEEP to meet patient’s inspiratory need

Use oxygen sparingly in the event the patient has a necessary PDA

Note: This table gives examples of cyanotic and noncyanotic heart disease.

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TREATMENT

Tetralogy of Fallot One or more surgeries are done to cure the defect. Surgery includes closing the ventricular septal defect and widening the pulmonary outflow track. Prognosis following surgery is usually good.10,13,14,15 A modified Blalock-Taussig procedure is used to provide temporary relief for tetralogy of Fallot.4,10 This procedure connects one branch of the aorta to either the left pulmonary artery or the right pulmonary artery. In recent years, most cardiac surgeons perform the modified version of Blalock-Taussig, in which a tube is positioned between the aorta and the pulmonary artery.4,10 The creation of a shunt helps to improve pulmonary blood flow. It goes without saying that a shunt is temporary, which means that at some point in the future, the child will need further surgeries to provide a permanent correction of this defect. In the meantime, if the child has adequate pulmonary blood flow to the lungs and is not showing symptoms of respiratory distress, most researchers project that he or she can live reasonably well into their teen years and beyond. Transposition of the Great Vessels Needless to say, oxygen alone will not solve the problem. In the intensive care units nowadays, the use of the ultrasound helps to differentiate the type of cardiac abnormality. Historically, a respiratory therapist would have provided some initial information by using the hyperoxia test.1,3,12 The hyperoxia test allows you to provide the patient with 100% of pure oxygen either by using a non-rebreather mask or through a mechanical ventilator. If this is determined to be a pure cardiac lesion, then what remains is a low PaO2 despite the high concentration of oxygen. If, on the other hand, this is determined to be a pure respiratory problem, provided it is not a situation like acute respiratory distress syndrome (ARDS), which poses its own problems, you should see a significant rise in PaO2 with the administration of the 100% oxygen. If there is confirmation that this is in fact a cardiac lesion, then be assured that all of our respiratory tricks of the trade will be null and void. A respiratory therapist

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provides support to this child until surgery happens, and the goal is that surgery takes place sooner rather than later. A review of the most current research shows that the administration of prostaglandin E1 has been used to significantly decrease the pulmonary blood pressure, which would facilitate blood flow through the lungs and then on to the body with oxygen-rich blood.8 Administration of prostaglandin E1 is done as a temporary relief prior to surgery, and this keeps the ductus arteriosus open. The type of surgery seen in most cardiac centers for this defect is called the arterial switch.4,13,14,15 This surgery has been shown to permanently correct this defect and has resulted in better than 90% survival.4,13,14,15 However, arterial switch can also create debilitating complications such as heart block or asynchrony between the atria and the ventricles. Can you imagine the atria and ventricle not having a coordinated “rhythm”? Tricuspid Atresia Babies born with tricuspid atresia will, on most occasions, require respiratory support via an endotracheal tube, followed by an infusion of prostaglandin E1.8,10 Prostaglandin E1 is used to maintain blood volume in the interim until surgery is done. Most infants undergo surgery in several stages before permanent correction is completed. (Note that it is not within the scope of this guide to mold you into surgeons, but as a respiratory therapist, having an appreciation for what happens in surgery only adds to your level of competence when managing the patient’s respiratory care. Acquired knowledge never hurts and can never be taken from you.) As stated earlier, tricuspid atresia is treated in stages. These stages begin with the Norwood procedure, followed by the Glenn shunt or hemiFontan procedure, and, finally, the Fontan procedure. Table 9-3 highlights the stages of treatment. A word about Prostaglandin E1: this medication is used to keep a ductus open after birth. This is important because in many of these conditions, there is limited connection between the right side and the left side of the heart. You need some type of hole in order to have some mixing of blood. The American Academy of Pediatrics cautioned that the side

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Table 9-3 Surgical Treatment for Cardiac Defects by Stage Stage I

Stage II

Stage III

Procedure

Norwood operation

Glenn shunt or hemi-Fontan procedure

Fontan procedure

Child’s age

Occurs within the first few days of life

4 to 6 months of age

18 months to 3 years

Description

An artificial shunt is placed to optimize blood flow to the lungs.

This establishes a connection between half of the veins that carry deoxygenated blood from the body to the lungs.

This establishes the final connection between the remaining veins that carry deoxygenated blood directly to the lungs. The right ventricle now returns to its original function as a pumping chamber.

effects of this medication include apnea, pulmonary congestion, fever, hypotension, seizure, and diarrhea.1 It should come as no surprise when the physician suggests that the patient be electively intubated while receiving prostaglandin E1 because this drug may further compromise the patient’s respiratory status. Although the patient may be subject to more than one surgery, the alternative is to have a heart transplant; however, there are not many infant heart donors available. Total Anomalous Pulmonary Venous Return The main goal of surgery for TAPVR is to connect the pulmonary veins back to the left atrium, as in the normal heart. To complete this, the surgery most often used allows the left atrium and the pulmonary veins to be opened and then sewn together. Depending on the type of TAPVR, the surgeon may have to tie off the pulmonary vein that was once connected to the superior vena cava. This would allow blood to bypass this vessel during the closing phase. Lastly, the atrial septal defect, which was probably the lifesaver, is now able to be closed with some type of patch that is sutured into the hole between the atria. This procedure seems so simple, and it can be. The Johns Hopkins University Children’s Heart Center sug-

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gests that postoperative care can be as short as 3 to 5 days, depending on the type of surgical procedure performed.10 Although cyanotic heart conditions may present an immediate risk of respiratory compromise, noncyanotic heart lesion can also present risks, but to somewhat of a lesser degree. Atrial Septal Defect Surgical intervention is required for an isolated ASD in a patient who is symptomatic. There are at least two procedures used to close an ASD: 1. Patching or suturing during open heart surgery using a monofila-

ment thread of polypropylene used for a small ASD. Large holes may be covered with a patch made of pieces of the pericardium or a silk synthetic material like Dacron or Teflon.10 2. Transcatheter closure is when a device is introduced into the heart using a catheter during a cardiac catheterization procedure. The procedure is accomplished by using the Amplatzer sizing balloon, which is used to measure the size of the hole; this is followed by a septal occluder, which is used to close the ASD.10 Ventricular Septal Defect Nonsurgical Treatment For children who show signs of congestive heart failure, there are a number of nonsurgical interventions that can be used: • • • •

Digitalis to improve the strength of the heart Diuretics to decrease the fluid around the lung Bronchodilators to improve the pulmonary function Chest physiotherapy to improve mucus clearance, which helps to diminish the effects of respiratory infections • Antibiotics to resolve the respiratory infection • Nutritional supplements to help the infant grow Surgical Treatment Surgical procedure for a small VSD is done by either suturing or patching the VSD with a monofilament thread made of Prolene or polypropylene.10 A large VSD may require a patch using

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pieces of the pericardium or silk or synthetic material like Dacron or Teflon.10 Postoperative outcome of this surgery is good, and the mortality risk is very low. Patent Ductus Arteriosus Nonsurgical Treatment Indomethacin and ibuprofen have been used to promote patent ductus closure. Both medications are considered prostaglandin inhibitors. Prostaglandins function in utero to keep the patent ductus arteriosus open; however, after birth and subsequently with the child’s first breath and the increase in the partial pressure of oxygen, prostaglandin is no longer needed.16,17 Overmeire et al. compared indomethacin to ibuprofen in the preterm infant and found that ibuprofen was just as effective in the treatment of patent ductus arteriosus on the third day.18 Pai et al. showed that ibuprofen had fewer side effects to the cerebral, renal, and mesenteric blood flow in the premature infant than indomethacin.19 A recent study by Cherif et al. compared intravenous ibuprofen (marketed as NeoProfen) to oral ibuprofen and found that oral ibuprofen was as good as the intravenous route for ductal closure.20 Surgical Treatment A large patent ductus arteriosus that does not respond to medication may benefit from surgery. Typical surgery closes a PDA by means of a PDA ligation.4 This ties off the ductus with some type of synthetic material.10,21 The end result of this procedure is to allow blood to pass to the lungs by means of the pulmonary arteries, where it picks up oxygen-rich blood. This procedure has proven to be very successful in a number of infants and children; it by far is one of the more common surgical procedures you will encounter as a respiratory therapist in the NICU area. Coarctation of the Aorta Surgery is recommended to correct a narrowed aorta. If the area that is narrowed is small, the surgery will remove the narrow part and connect the two ends back together. If the narrowed area is large, then the surgery will require removal of a large part of the narrowed area and replacement

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with some type of graft.10 This graft is designed to fill in the gap. Because there are complications with surgery, it is recommended that surgery be done before the age of 10.10 In reality, most cardiac centers believe surgery should really happen when the patient is an infant. Research has shown that those who wait until young adulthood tend to die before they reach age 40.10 Congestive Heart Failure The American Academy of Pediatrics (2006) suggests the following:1 • • • • • • • •

Supplemental oxygen Assisted ventilation if necessary Keep patient in either high Fowler or semi-Fowler’s position Ongoing monitoring with heart monitor Ongoing monitoring with pulse oximetry IV access if necessary Drug therapy with Lasix, nitroglycerin, and digoxin Dopamine and dobutamine to improve cardiac output in the event of circulatory shock • Prostaglandin E1 Summary

Even though we have come to the end of our discussion on congenital heart defects, it is by far not the end of the mounds of literature on this topic. This chapter was intended to highlight only those defects that occur more often than others. It is highly likely that you will see patients with a congenital heart defect that was not discussed in this guide. Have no fear—as a budding connoisseur of research, you know where to go and what to look for. The Internet is chock-full of readable information geared toward the consumer; however, if you want to know more about what the experts say, go to the National Library of Medicine and you will encounter a world of knowledge on this subject. It is very likely that the congenital heart defect you found interesting is probably well described in the literature.

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✔✔ The four most common cyanotic heart diseases are: • Tetralogy of Fallot • Transposition of the great vessels (TGF) • Tricuspid atresia • Total anomalous pulmonary venous return (TAPVR) ✔✔ The four most common noncyanotic heart diseases are: • Atrial septal defect (ASD) • Ventricular septal defect (VSD) • Patent ductus arteriosus (PDA) • Coarctation of the aorta ✔✔ Congenital heart disease affects 9 out of 1000 babies born each year. ✔✔ A prominent characteristic of a cyanotic heart disease is its blue discoloration known as cyanosis. ✔✔ Noncyanotic heart disease may or may not have cyanosis, depending on the specific cardiac condition. References 1. American Academy of Pediatrics and the American College of Emergency Physicians. (2007). APLS: The pediatric emergency medicine resource (Rev. 4th ed.). Sudbury, MA: Jones and Bartlett Publishers. 2. American Heart Association. (n.d.). American Heart Association fact sheet. Retrieved May 21, 2007, from http://www. americanheart.org/presenter.jhtml?identifier=3028667 3. Whitaker, K. (2001). Comprehensive perinatal and pediatric respiratory care (3rd ed.). Albany, NY: Delmar Thomson. 4. Avery, G., Fletcher, M., & Macdonald, M. (1994). Neonatology pathophysiology and management of the newborn (4th ed.). Philadelphia: Lippincott. 5. National Heart Lung and Blood Institute. (2007, December). Diseases and conditions index. Retrieved December 12, 2007, from http://www.nhlbi.nih.gov/health/dci/Diseases/chd/chd_what.html 6. Hoffman, J., & Kaplan, S. (2002). The incidence of congenital heart disease. Journal of American College of Cardiology, 39, 1890–1900. 7. Gelson, E., Gatzoulis, M., Steer, P., Lupton, M., & Johnson, M. (2008, March). Tetralogy of Fallot: Maternal and neonatal outcomes. BJOG: An International Journal of Obstetrics & Gynaecology, 115 (3), 398–402. 8. Rosenzweig, E., Kerstein, D., & Barst, R. (1999). Long-term prostacyclin for pulmonary hypertension with associated congenital heart defects. Circulation, 99, 1858–1865. 9. Rao, P. S. Tricuspid atresia. (2009, February). Retrieved February 29, 2008, from http://emedicine.medscape.com/ article/900832-overview 10. Cove Point Foundation, Congenital Heart Disease, Helen B. Taussig Children’s Heart Center, Johns Hopkins University. (2009 May). Retrieved June 13, 2009, from http://www.pted.org 11. Afiune, J., Singer, J., & Leone, C. (2005). Echocardiographic post-neonatal progress of preterm neonates with patent ductus arteriosus. Journal of Pediatrics, 81(6), 454–460.

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12. Kacmarek, R., Dimas, S., & Mack, C. (2005). The essentials of respiratory care (4th ed.). St. Louis, MO: Mosby Elsevier. 13. Behrman, R. E. (2004). Nelson textbook of pediatrics (17th ed.). Philadelphia: Saunders. 14. Boyes-Barratt, B. (1971). Cardiac surgery in neonates and infants. Circulation, 44, 924–925. Retrieved December 29, 2007, from http://www.circ.ahajournals.org/cgi/reprint/44/5/924 15. Zipes, D. P., Libby, P., Bonow, R., & Braunwald, E. (eds.). (2005). Braunwald’s heart disease: A textbook of cardiovascular medicine (7th ed.). St. Louis, MO; Saunders, p. 1515. 16. Clyman R. (2007, March). Patent ductus arteriosus: Evidence for and against treatment. Journal of Pediatrics, 150 (3), 216–219. 17. Dolberg, S., Lusky, A., & Reichman, B. (2005). Patent ductus arteriosus, indomethacin, and necrotizing enterocolitis in very low birth weight infants: A population-based study. Journal of Pediatric Gastroenterology Nutrition, 40(2), 184–188. 18. Overmeire, B., Smets, K., Lecoutere, D., Van De Broek, H., Weyler, J., De Groote, K., et al. (2000, September). A comparison of ibuprofen and indomethacin for closure of patent ductus arteriosus. New England Journal of Medicine, 343 (10), 674–681. 19. Pai, V. B., Sakadjian, A., Puthoff, T. D. (2008, September). Ibuprofen lysine for the prevention and treatment of patent ductus arteriosus. Pharmacotherapy, 28 (9), 1162–1182. 20. Cherif, A., Khrouf, N., Jabnoun, S., Mokrani, C., Amara, M., Guellouze, N., et al. (2008). Randomized pilot study comparing oral ibuprofen with intravenous ibuprofen in very low birth weight infants with patent ductus arteriosus. Pediatrics, 122, e1256–e1261. 21. Kaemmerer, H. (2004, November). Surgical treatment of patent ductus arteriosus: A new historical perspective. American Journal of Cardiology, 94(9), 1153–1154.

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Chapter

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Neuromuscular Diseases Chapter Outline DEFINE • Spinal muscular atrophy • Duchenne muscular dystrophy DESCRIBE • Spinal muscular atrophy • Duchenne muscular dystrophy DISTINGUISH • Spinal muscular atrophy related condition • Congenital muscular dystrophy RESEARCH • Relevant research on the most common neuromuscular conditions that affect young children

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TREATMENT • Treatment options for patients with neuromuscular conditions

Key Terms Duchenne muscular dystrophy (DMD) Mechanical ventilation Noninvasive ventilation Respiratory failure Spinal muscular atrophy (SMA)

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Chapter 10 Neuromuscular Diseases

INTRODUCTION

There are significant numbers of neuromuscular diseases that affect children; however, this neonatal/pediatric guide book highlights the two conditions that most often affect young children and adolescents. While researching this topic, it occurred to me that many respiratory therapists have limited exposure to patients who are diagnosed with spinal muscular atrophy (SMA) or Duchenne muscular dystrophy (DMD) unless they have worked in a rehabilitation environment. Because many respiratory therapists have not had this opportunity, for me personally, it was awe inspiring to realize how much respiratory care these patients need. The literature shows that there are a number of neuromuscular conditions that affect children and adults. In most cases, the children are cared for at home, so when institutionalized care is needed for this type of patient, it is done in a long-term rehabilitation facility that specializes in caring for children with chronic conditions. The facilities have the benefit of being able to provide very coordinated care from a variety of disciplines. This is not to say that acute facilities lack this ability, because acute care can and often does provide integrated care; however, acute care lacks the time. Long-term facilities are by far a better environment to continue integrated care. I point this out because as a respiratory therapist, I have seen this coordination firsthand. To me, care plan coordination, followed by family education, is the hallmark of these institutions. DEFINE

Spinal muscular atrophy (SMA) is a hereditary ailment that results in weakness and muscle wasting, particularly in the arms and legs of infants and children.1,2 Avery et al. report that children born with the infantile form of spinal muscular atrophy inherited it as an autosomal recessive disorder.3 According to the National Institute of Neurological Disorders and Stroke (NINDS), SMA is classified as type I, II, or III, and these designations are determined by the age of onset and recognized symptoms.1,2 It affects males and females and tends to run in families. There is a missing gene called the survival motor neuron gene that is responsible for the production of protein necessary for the proper function of the motor neu-

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ron. In children with SMA, this protein is missing and the motor neuron in the spinal cord is weakened and eventually dies. Because there is no cure for any type of SMA, the prognosis is poor for infants and children with SMA type I and better for children with SMA types II and III. There are a number of interventions that can manage the symptoms and prevent respiratory complications and infections. This is especially significant for patients with SMA type I. Duchenne muscular dystrophy (DMD) is a condition that has been described in history since 1830, when Sir Charles Bell wrote about an illness that causes progressive weakness in boys.4 The early years of the illness are characterized by generalized weakness and muscle damage that results in muscle tissue being replaced with fat and connective tissue.4 It was not until the 1850s, when neurologist Guillaume Duchenne gave a comprehensive report of 13 boys who grew progressively weaker, lost the ability to walk, and died at an early age, that this disease was properly classified.4 Duchenne described this illness as the most common and severe form of the disease.4,5,6 Duchenne muscular dystrophy (DMD) refers to a group of more than 30 genetic diseases that cause progressive weakness and degeneration of the skeletal muscles.4,5,6 DMD is an X-linked (sexlinked) recessive condition that is inherited. Mothers are the carriers and pass the X chromosome to their sons. Fathers who are carriers cannot pass the X chromosome to their sons, but they can pass the X chromosome to their daughters, who then become carriers of the gene. The protein dystrophin is a membrane-associated protein found in small amounts in normal muscles but is deficient or flawed in Duchenne muscular dystrophy. This protein is found in the smooth muscle lining of the stomach. DESCRIBE

Spinal muscular atrophy (SMA) is described as an abnormal malformation of the survival motor neuron gene, which is made of a protein that is essential to the development of the motor neuron. Failed production of this gene causes the lower motor neuron in the spinal cord to degenerate or die. Babies affected by SMA have floppy arms and legs and are unable to sit, stand, or walk. There are three varieties of spinal muscular atrophy:

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1. SMA type I is named Werdnig-Hoffman disease or infantile-onset

SMA. It is identified within the first few months of birth, and symptoms include floppy legs and arms, poor tone, swallowing difficulties, loud breathing, and poor sucking reflex. Type I is considered the most severe. Patients’ life expectancy is poor: they usually die within the first 2 years.1 2. SMA type II, named juvenile SMA, occurs in children 6 to 18 months of age. Legs appear to be more affected than the arms. Children diagnosed with type II can usually sit without help, and many may stand or walk with assistance. Their life expectancy is based on how old they are when the first symptoms appear. If symptoms appear when the child is older, then life expectancy tends to be longer.1 3. SMA type III, named Wohlfart-Kugelberg-Welander syndrome, occurs after 18 months and as late as the adolescence years. It is considered mild SMA because these children tend to stand or walk without help, even though they may have difficulty rising from a sitting position. These children go on to live relatively normal lives. In this population, evidence of their symptoms may not appear for years.1 Clinical Note SMA, regardless of the type, is a devastating illness. My first personal experience with a patient diagnosed with SMA was in a pulmonary rehabilitative clinic. A beautiful little girl, 2 years old, was diagnosed with SMA. She had the classic symptoms of SMA type I: floppy legs and arms, and a chest wall that caved inward, which denoted advanced stages of the condition. Her mother was dedicated to seeing that her daughter received as much respiratory support as possible. Even though this child could barely breathe, she appeared to be a typical little toddler who still wanted to explore everything around her. The children I have cared for who were diagnosed with SMA type I always seemed to have such happy spirits despite their circumstances. The goal in the pulmonary rehabilitative clinic is to facilitate good bronchopulmonary hygiene and teach parents how to use the various devices that promote good pulmonary toiletry at home.

Duchenne muscular dystrophy (DMD) is characterized by the enlargement of calf muscles of the legs secondary to an accumulation of fat and connective tissue in the muscles.4,5 This causes the classic symptoms

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of frequent falls and difficulty getting up from a sitting or a lying position.4,5 DMD onset occurs in male children between the ages of 2 and 6 years, with progressively worsening symptom as the child ages. In 1986, Muscular Dystrophy Association–funded research indicates that children who inherit the X-linked recessive gene are likely to have a nonworking version of the protein dystrophin, a protein that helps the muscle tissue repair itself, which has been linked as the cause of DMD.4,5 According to this research, boys born with DMD have little to no dystrophin in their muscles.6 DMD affects approximately 1 in 3500 male births. Although it primarily affects boys, girls who are carriers of the gene can show symptoms of DMD. Table 10-1 compares SMA and DMD. DISTINGUISH

Spinal muscular atrophy phenotypes are conditions that are considered mutations because they do not have the chromosome 5 abnormality that affects the SMA protein production to the same extent as in those children with SMA. In SMA, phenotypes tend to be a mild form and show evidence of more protein production than in SMA.1 Luca Cartegni and Adrian Krainer characterized SMA as a progressive degeneration of the spinal motor neuron and the leading genetic cause of mortality in infants, occurring in 1 and 10,000 live births. Their research showed that SMA is caused by a loss of both functional copies of survival of motor neuron 1 (SMN1),7 yet each person carries an identical normal SMN2 gene. Their research recognized that in the SMA phenotype, the SMN2 gene, which is identical to the SMN1, is only partially functional and not able to protect against the genetic defect of spinal muscular atrophy.7 Congenital muscular dystrophy has been classified as a group of congenital abnormalities of the skeletal muscles. Brown et al. report that the hallmark of congenital muscular dystrophy is the presence of significant muscle weakness at birth with elevated serum creatine kinase levels.8 This condition is seen early in infancy, compared to DMD, which is typically seen 6 to 9 months after birth. A form of congenital muscular dystrophy is associated with weak facial and extremity muscles. In these children, brain abnormalities that affect speech and cognition are evident. Seizures are also seen in children with this type of muscular

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Table 10-1 Highlights of the Differences Between SMA and DMD

Age When Symptoms Appear

SMA I—WerdnigHoffman (infantile form of spinal muscular atrophy)

SMA II—Juvenile SMA (same as SMA I)

SMA III—WohlfartKugelbergWelander (same as SMA I)

DMD—Duchenne Muscular Dystrophy (weakness and degeneration of the skeletal muscles)

Infancy—first few months of life

6 months to 18 months

After 18 months

Between 2 years and 6 years

Sex

Male and female

Male and female

Male and female

Male

Genetic Defect

Missing survival motor gene needed to produce protein for the proper function of the motor neuron

Same as SMA I

Same as SMA I

Missing the protein dystrophin, which helps the muscle tissue repair itself; X-linked recessive gene

Area of Body Most Affected

Arms and legs

Legs affected more than arms

Legs affected more than arms

Calf muscles of the legs

Clinical Presentation

Unable to sit, stand, or walk; noticeable respiratory distress, ineffective cough

Can sit without assistance; may stand or walk with assistance

Able to sit, stand, or walk without assistance; however, there is a tendency to have some difficulty rising from the sitting position

Frequent falls, difficulty rising from a sitting position

Outcome

Poor clinical prognosis; patients usually die by the age of 2 years

Good clinical prognosis with good pulmonary hygiene

Good clinical prognosis

Death occurs in the late 20s and early 30s; however, good pulmonary hygiene enhances quality of life

dystrophy. The research indicates that this defect is related to the lack of or malfunctioning protein called merosin.4 Merosin is one of the subunits of a muscle basement membrane protein called laminin. Infants who are merosin deficient display generalized muscle weakness and hypotonia early.

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RESEARCH

There are three types of SMA, and research has concentrated on SMA type I, the most severe of the three. Because SMA is incurable at this time, the available research focuses on prevention and management of symptoms that often lead to respiratory compromise. There are several studies that describe various methods of treatment for SMA type I patients who present in respiratory failure. Bach et al. (2000) did a retrospective study that suggested that SMA type I patients should receive a regimen of manually and mechanical assisted coughing to promote mucus clearance.9 They also suggested that a number of children would benefit from noninvasive ventilation, particularly during sleep. The aim of this study was to demonstrate that most SMA type I children can avoid the need for a tracheostomy tube. Another study, by Ioos et al. (2004), agreed that good respiratory management was significant; however, they felt strongly that children who required a significant amount of positive pressure ventilation would benefit from having a tracheostomy tube in place.10 There was a significant amount of discourse in the research as to which management course is better; however, regardless of which option is most beneficial, the respiratory therapist will be fully engaged in carrying out the treatment plan. The Centers for Disease Control and Prevention (CDC) projects that Duchenne muscular dystrophy occur in approximately 1 in every 3,500 to 5,000 births in the United States.6 Similar to the discussion on spinal muscular atrophy, DMD tends to be a progressive disease affecting the respiratory muscles, causing respiratory muscle weakness.11 Kohler and his group studied the quality of life of patients with DMD in relation to physical disability, pulmonary function, and the need for mechanical ventilation.12 Their research supports the current thought that DMD leads to muscle weakness in the legs and arms and increased manifestation of both respiratory and cardiac failure. Further, their study showed that most patients become wheelchair-bound during their late 20s, and in the advanced stages of the condition, develop chronic respiratory failure, necessitating the need for mechanical ventilation.12 Historically, many of these patients received a tracheostomy tube for long-term posi-

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tive pressure ventilation, but Bach et al. purports the idea that noninvasive positive pressure ventilation (NIPPV) has increased the survival rate of patients with Duchenne and lessened the need for a tracheostomy tube and mechanical ventilation.13 One might assume that the quality of life for patients with DMD would be severely impaired; however, Kohler et al. did not find a correlation between their quality of life and their physical impairment. In fact, these researchers report that patients with Duchenne muscular dystrophy actually experienced a high quality of life despite their physical handicaps.12 Kohler et al. further highlight the perceived notion by healthcare workers that patients with Duchenne muscular dystrophy have a low quality of life. In fact, the patients in their study demonstrated reasonable satisfaction with their quality of life despite the advanced disability, respiratory impairment, and dependence on technology and other lifesustaining therapies.13 Clinical Note I am reminded of my own observations of patients with DMD and SMA and how happy they seemed despite their circumstances. I recall a 16-year-old young man diagnosed with DMD whom I worked with when I did home care for a local durable medical equipment (DME) company. This young man had a tracheostomy tube and was on a ventilator 24 hours a day. He was in the advance stages of his condition, yet he loved life, and because he was disabled, with the help of his caregivers he was able to work through the medical and governmental systems to obtain the necessary services that he needed. He had a wheelchair with a portable ventilator fitted on the back. This young man had mobility, which allowed him to participate in a number of outside activities, and I was sometimes assigned to accompany him.

The quality of life for patients with DMD appears high, yet the life expectancy of children with DMD is still low given that death usually occurs in their late 20s to early 30s.12 Over the course of many years, research has concentrated on how to maintain quality of life of patients with DMD by improving their pulmonary lung functions. The American Thoracic Society (ATS) issued a consensus statement describing the current standard of care recommended for patients with DMD.14 The following list summarizes their statement:

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• Patients should have routine evaluation of respiratory function. • Patients should have access to specialists in pulmonology, neurology, cardiology, nutrition, physical medicine, orthopedic surgery, mental health, sleep medicine, and social work. • Patients should visit a physician specializing in respiratory care twice yearly after confinement to a wheelchair, when a fall in vital capacity below 80% is predicted, and/or at age 12 years. • Children should have a least one visit with a physician specializing in pediatric respiratory care early in the course of the disease. • Individuals who require mechanically assisted airway clearance therapy or mechanically assisted ventilation should have access to a pulmonologist every 3 to 6 months. • All patients with DMD should undergo pulmonary and cardiac evaluations before surgeries. • All patients with DMD should receive the pneumococcal vaccine and an annual influenza vaccination. • Patients should have an objective evaluation at each clinic visit of oxyhemoglobin saturation by pulse oximetry and pulmonary function testing. • A baseline arterial blood gas sample should be taken to assess the presence of alveolar hypoventilation. • Patients should be evaluated for other respiratory disorders—for example, obstructive sleep apnea, oropharyngeal aspiration, gastroesophageal reflux, and asthma. • Annual laboratory studies should be done for wheelchair-bound patients. TREATMENT

SMA and DMD As respiratory therapists, you are integral in the provision of respiratory care to patients with both DMD and SMA. This section provides recommendations for the respiratory management of patients with DMD and SMA. Airway clearance is the key to prevention of atelectasis and pneumonia.9,13,15,16 Early interventions decrease the risk of respiratory failure and minimize the need for hospitalizations.17,18 There are a number of

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respiratory therapy maneuvers used to improve effective airway clearance which promote good lung health: • Assisted coughing—Most children will require assistance with coughing, followed by a forced expiratory effort. Maximum insufflation capacity is the volume of air held in the lung against a closed glottis.15,18 This requires the patient to be trained in air stacking, which involves taking in a series of breaths without exhaling. This can be done with a hand resuscitator bag, an intermittent positive pressure breathing machine (IPPB), or mechanical ventilator. Air stacking is followed by the forced exhalation, which is done by pushing on the upper abdominal chest wall.15,18 To demonstrate this, the respiratory therapist will place his or her hands around the chest wall, while the child takes as deep a breath as possible and then moves his or her hands inward, as if pressing the diaphragm in an upward motion. A very young child might require additional therapy, such as manual chest physiotherapy, followed by the use of some type of suctioning device to remove secretions. • Manual chest physiotherapy (CPT)—This can be done by using hand clapping, mechanical percussors, or a therapist-designed CPT mask, along with postural drainage, followed by some type of suctioning device to remove secretions. If the child weighs 40 pounds or more, you might be able to use the chest vest. This is important if you are assigned to the PICU where you have an older child who might benefit from chest physiotherapy; however, hand clapping and/or other modalities might not be feasible or effective. Figure 10-1 shows a chest vest; Figure 10-2 A–C shows other types of chest physiotherapy devices. Over the years, there has been a proliferation of devices that now complement manual chest physiotherapy. Figure 10-3 illustrates manual chest physiotherapy positioning. As a respiratory therapist, use your clinical judgment to recommend the best options. • Intrapulmonary percussive ventilation (IPV)—The American Thoracic Society has determined that this is an option for children with neuromuscular disease. IPV uses a machine that delivers positive pressure to the airway based on high frequency and low amplitude oscillation.19 This therapy is used when other therapies have failed.

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Content removed due to copyright restrictions

Figure 10-1 High frequency chest wall oscillatory vest The Vest® Airway Clearance System is a registered trademark of Hill-Rom Services, Inc. © 2009 Hill-Rom Services, Inc. REPRINTED WITH PERMISSION-ALL RIGHTS RESERVED

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A

B

C Figure 10-2 Mechanical percussor (A) and manual percussors (B and C)

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R

231

L

Elevate 18" Anterior

Right lateral segment

R

L

Anterior

Anterior segment of upper lobes

L

R

Posterior

Right posterior segment

R

Superior segments

L Anterior

Figure 10-3 Positioning used while providing manual chest physiotherapy (Continues)

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R

L


Right middle lobe

R

L


Left lingular

L

R

Elevate 18" Posterior

Posterior segments

L

R

Elevate 18"

Anterior segment of lower lobes

Posterior

Figure 10-3 Positioning used while providing manual chest physiotherapy (Continued)

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L

233

R

Posterior

Posterior apical segment

R

L

Anterior

Anterior upper segment of upper lobes

L

R

Posterior

Left posterior segment

R

L

Elevate 18"

Left lateral segment

Anterior

Figure 10-3 Positioning used while providing manual chest physiotherapy

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Figure 10-4 Intrapulmonary percussive ventilation

In neuromuscular disease centers that specialize in DMD and SMA, the intrapulmonary percussive ventilator is used mainly as adjunctive therapy in pulmonary rehabilitation. Figure 10-4 shows IPV. • Hyperinsufflation therapy using a coughlator—This device pushes volumes of air into the lungs at a set pressure, which can be done on inspiration, expiration, or both. The mechanical in-exsufflator (see Figure 10–5), which was designed specifically for use in this patient population, provides mechanically assisted coughing.15,16,17,18 According to Bach and his colleagues, the in-exsufflator insufflation pressure

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Figure 10-5 Mechanical coughlator

is usually set at +35 to +60, followed by exsufflation pressure of –30 to –60 cm H20, followed by abdominal thrust or tussive squeezes applied to the chest wall. The Bach et al. study concluded that the use of respiratory muscle aids can reduce complications resulting from respiratory compromise.15,16,17,18 Another study, conducted by Seong-Woong and Bach, demonstrated that when neuromuscular patients were trained in air stacking, their lung insufflation was maximized.18 The aim of their study was to investigate the effects of having the patient perform air stacking maneuvers with 10 to 15 maximal lung insufflations three times a day with either a hand resuscitator bag or a volume ventilator using a mouthpiece or a nasal

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interface.18 Seong-Woong and Bach report significant improvement in the quality of life for patients with neuromuscular disease. The most recent research concurs that the mechanical in-exsufflator was considered safe, well tolerated, and effective in decreasing pulmonary complications.15 NIPPV Toward the latter stages of both DMD and SMA, respiratory muscle weakness becomes apparent, necessitating the need for assisted positive pressure ventilation. Bach recommends the use of a volume ventilator to a mask or nasal prongs to facilitate positive pressure breaths.18,19 Many of these patients are cared for at home; the use of portable ventilators, CPAP, or bi-level devices can be used. If and when these children are admitted to the hospital, there has to be a determination on what type of mechanical device will be best for the patient based on his or her condition. There is much debate regarding whether there is a need for the tracheostomy tube. In the clinical setting, decisions are based on the presentation of the patient. If the patient has a tracheostomy tube, the equipment is set accordingly. The same is true if the patient does not have a tracheostomy tube. When determining the appropriate settings for noninvasive ventilation, arterial blood gas provides essential information regarding ventilation and oxygenation. Based on this information and in consultation with the medical team, the respiratory therapist will determine the most appropriate ventilator setting for the patient. Invasive Inflation There will be a group of patients in this population who will ultimately succumb to respiratory failure, requiring invasive mechanical ventilation. It is highly likely that these patients will have a tracheostomy tube in place for long-term mechanical ventilation. ATS recommends that invasive ventilation should be considered when contraindications for noninvasive ventilation are present.15 Patients requiring mechanical ventilation will need the same degree of care and monitoring regardless of the diagnosis.

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Summary

✔✔ SMA affects both male and female children. ✔✔ There are three variations of SMA: type I, type II, and type III. ✔✔ Type I has the worst prognosis affecting infants and children under 6 months of age. These infants die before 2 years of age. ✔✔ Type II called juvenile SMA affects infants and children between 6 to 18 months. These children can usually sit alone and many can walk with assistance. ✔✔ Type III named Wohlfart-Kugelberg-Welander syndrome, occurs after 18 months and as late as the adolescence years. It is considered mild SMA because these children tend to stand or walk without help. ✔✔ DMD affects mainly boys from 2 to 6 years of age; however girls can be carriers of the X-link recessive gene. ✔✔ DMD children are missing the protein dystropin, which has been linked to progressive muscle weakness. ✔✔ DMD is characterized as having progressive muscle weakness, degeneration of the skeletal muscles, inability to use arms and legs, and weakened respiratory muscles. Both SMA and DMD require good pulmonary hygiene to prevent respiratory infections, which may lead to respiratory insufficiency and ultimately to respiratory failure. One main responsibility of a neonatal/ pediatric respiratory therapist is to provide good pulmonary hygiene therapy. References 1. Muscular Dystrophy Association. (2008, June). Facts about spinal muscular atrophy (SMA). Retrieved February 7, 2008, from http://www.mda.org/publications/fa-sma-qa.html 2. National Institute of Neurological Disorders and Stroke. (n.d.). NINDS Spinal muscular atrophy information page. Retrieved February 7, 2008, from http://www.ninds.nih.gov/disorders/sma/sma.htm 3. Avery, G., Fletcher, M., & Macdonald, M. (1994). Neonatology pathophysiology and management of the newborn (4th ed.). Philadelphia: Lippincott. 4. Muscular Dystrophy Association. (n.d.) Facts about Duchenne muscular dystrophy (DMD). Retrieved February 7, 2008, from http://www.mda.org/publications/fa-dmdbmd.html

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5. National Institute of Neurological Disorders and Stroke. (n.d.). Muscular dystrophy: Hope through research. Retrieved February 7, 2008, from http://www.ninds.nih.gov/disorders/md/detail_md.htm 6. Centers for Disease Control and Prevention, National Center on Birth Defects and Developmental Disabilities. (2005, July 27). Retrieved February 20, 2008, from http://www.cdc.gov/ncbddd/bd/default.htm 7. Cartegni, L., & Krainer, A. R. (2002, April). Disruption of an SF2/ASF-dependent exonic splicing enhancer in SMN2 causes spinal muscular atrophy in the absence of SMN1. Genetics Nature, 30, 377–384. Retrieved February 4, 2008, from http://www.nature.com/ng/journal/v30/n4/abs/ng854.html 8. Brown, R. H., Grant, P. E., & Pierson, C. R. (2006, November). Case 35–2006: A Newborn Boy with Hypotonia. New England Journal of Medicine, 355 (20), 2132–2142. Retrieved December 24, 2008, from http://content.nejm.org/cgi/ content/extract/355/20/2132 9. Bach, J. R., Baird, J. S., Plosky, D., Navado, J., & Weaver, B. (2002, July). Spinal muscular atrophy type 1: Management and outcomes. Pediatric Pulmononology, 34 (1), 16–22. 10. Ioos, C., Leclair-Richard, D., Mrad, S., Barios, A., & Estournet-Mathiaud, B. (2004). Respiratory capacity course in patients with infantile spinal muscular atrophy. Chest, 126, 831–837. 11. Hahn, A., Bach, J., Delaubier, A., Renardel-Irani, A., Guillou, C., Rideau, Y. (1997, January). Clinical implications of maximal respiratory pressure determination for individuals with Duchenne muscular dystrophy. Archives of Physical Medicine and Rehabilitation, 78 (1), 1–6. 12. Kohler, M., Clarenbach, C., Boni, L., Brack, T., Russi, E., & Bloch, K. (2005, June). Quality of life, physical disability, and respiratory impairment in Duchenne muscular dystrophy. American Journal of Respiratory and Critical Care Medicine, 172, 1032–1036. 13. Bach, J. R., Niranjan, V., & Weaver, B. (2000). Spinal muscular atrophy type 1: A noninvasive respiratory management approach. Chest, 117, 1100–1105. 14. American Thoracic Society. (2004). Respiratory care of the patient with Duchenne muscular dystrophy: ATS consensus statement. American Journal of Respiratory and Critical Care Medicine, 170, 456–465. 15. Miske, L., Hickey, E., Kolb, S., Weiner, D., & Panitch, H. Use of the mechanical in-exsufflator in pediatric patients with neuromuscular disease and impaired cough. Chest, 125, 1406–1412. 16. Bach, J. R. (1993). Mechanical insufflation-exsufflation: Comparison of peak expiratory flows with manually assisted and unassisted coughing techniques. Chest, 104, 1553–1562. Retrieved February 7, 2008, from http://www.chestjournal.org/ cgi/content/abstract/104/5/1553 17. Tzeng, A., & Bach, J. R. (2000). Prevention of pulmonary morbidity for patients with neuromuscular disease. Chest, 118, 1390–1396. Retrieved February 7, 2008, from http://www.chestjournal.org/content/118/5/1390.abstract 18. Seong-Woong, K., & Bach, J. R. (2000). Maximum insufflation capacity. Chest, 118, 61–65. Retrieved February 7, 2008, from http://www.chestjournal.org/content/118/1/61.abstract?sid=342ef07f-f95c-413f-9b79-4b6a896f5777 19. Bach, J. R. (2005). There are other ways to manage spinal muscular atrophy type 1. Chest, 127, 1463–1464.

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Glossary

Acute lung injury A syndrome that is marked by severe lung injury that causes an acute hypoxemic respiratory failure, requiring high levels of oxygen and PEEP therapy. Acute lung injury often leads to acute respiratory distress syndrome (ARDS), which is the more severe form of acute lung injury. Acute respiratory distress syndrome A syndrome that is characterized by an inflammatory response that leads to damage of the alveolar-capillary membrane, which leads to progressive hypoxemic respiratory failure. This severe lung injury can lead to multiple organ failure.

Air leak syndrome This is also known as barotraumatic injuries. Pulmonary air leakage is associated with other procedures such as resuscitation and mechanical ventilation that cause increased pressure in the chest wall. This increase in pressure can cause injury to lung and heart tissue. Common air leaks described in infants are pneumothorax (spontaneous or tension), pneumomediastinum, pneumopericardium, and pulmonary interstitial emphysema. Anticholinergic This refers to the ability of a drug or enzyme to block the parasympathetic nerve impulses, causing a slowing or stopping of impulses to the cholinergic nerve fibers. Arterial blood gas Arterial blood gas is the withdrawing of blood from

an artery for the purpose of determining a patient’s pH, PaCO2, PaO2. Arterial blood gas helps to establish the diagnosis and treatment of acidbase disturbances. Arterial blood results may also provide other important chemistry values such as bicarbonate, sodium, potassium, and chloride.

Artificial airway A means of providing a functioning airway when the patient’s natural airway can no longer be used. An artificial airway device

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can be placed into the pharynx or directly into the trachea. Artificial airways are established for the following reasons: (1) airway compromise, (2) respiratory failure, and (3) protecting the airway.

Asthma Asthma is a chronic inflammation of the airways with reversible episodes of obstruction, caused by an increased reaction of the airways to various stimuli. The most notable characteristics of asthma are the squeezing of the muscles around the airway, increased production of mucus that clogs the airway, and inflammation of the airway. Asthmaticus Asthmaticus is now called severe asthma exacerbation. This is the most severe form of asthma that does not respond to the initial treatment with bronchodilators. The most notable characteristic is persistent wheezing with retraction that may result in high carbon dioxide levels. In most patients, it leads to progressive respiratory failure. Atrial septal defect This condition is characterized as a hole at some

point between the right and left atria. Small atrial septal defects are generally asymptomatic and cause no significant problems in infancy. Moderate to large atrial septal defects can cause large left-to-right shunts in children, which can inhibit growth and promote congestive heart failure.

Bacteremia This is bacteria in the blood, seen most often in patients

with sepsis. Sepsis is a systemic inflammatory response to infection in which there is a fever, hypothermia, increased heart rate, and increased respiratory rate. Sepsis can be caused by a bacterial infection.

Barotrauma. See air leak syndrome. Bronchiolitis This is the inflammation of the bronchioles that cause obstruction to the lower respiratory tract. Its most notable characteristics are low-grade fever, runny nose, cough, high respiratory rate, retractions, nasal flaring, inability to eat, and cyanosis. It affects children under the age of 5 and occurs most often in the winter months. It is caused mainly

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by the respiratory syncytial virus, but can be caused by a number of other viruses.

Bronchodilators Bronchodilators are drugs that relax the bronchial smooth muscles. There are three classification of these drugs: (1) beta2 adrenergic-receptor agonist, (2) methylxanthines, and (3) anticholinergic agents. Bronchodilators are widely used in the treatment of patients with asthma.

Budesonide (Pulmicort) An inhaled corticosteroid used in the treatment of infants with croup. Also used as maintenance medication in the treatment of asthma. Cardiac tamponade This is the accumulation of fluid in the pericardial sac, causing a compression of the heart and surrounding structures to be under pressure. Chronic lung disease (See chronic lung disease of the newborn) Chronic lung disease of the newborn (CLD) Historically known as bronchopulmonary dysplasia (BPD), this is a chronic respiratory disease that developed in infants exposed to mechanical ventilation and oxygen supplementation. It is described as a significant lung change in a premature infant who is diagnosed with respiratory distress syndrome that requires mechanical ventilation and/or high concentrations of inspired oxygen. This condition is also referred to as chronic lung disease. Chronic obstructive pulmonary disease This is a group of debilitating,

progressive, and potentially fatal lung diseases that have in common increased resistance to air movement, prolonged expiratory phase of respiration, and loss of the normal elasticity of the lung tissue. The following are conditions that are commonly referred to as chronic obstructive pulmonary disease (COPD): (1) emphysema—a loss of normal elasticity of the lung tissue, (2) chronic bronchitis—a chronic inflammation of the bronchial wall with an increase in mucus production, (3) asthmatic bronchitis—bronchitis compounded by wheezes, caused by spasm of hyper-

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reactive airways. Most patients with COPD are or were smokers: tobacco smoke exerts toxic effects on the lungs.

Coarctation of the aorta In this condition, there is a narrowing at some point along the aorta. The most notable characteristic of this defect is a significant increase in systemic blood pressure in the upper extremities compared to the blood pressure in the lower extremities. Coarctation of the aorta is the most common cause of congestive heart failure in the neonate. Congestive heart failure In infants and children, congestive heart fail-

ure is related to other congenital heart diseases. Right heart failure in infants can be attributed to some type of obstruction, either related to the flow of blood from one side of the heart to another. The most notable characteristic of congestive heart failure is an enlarged heart on chest radiography.

Cool mist tent This is a device used to deliver supplemental oxygen to

an infant. It provides aerosolized particles as a fine mist small enough to be inhaled. It is still used but not recommended in the treatment of patients with croup.

Corticosteroids A group of steroid hormones secreted by the cortex of the adrenal gland or manufactured for use as a drug to treat inflammatory illnesses such as asthma, arthritis, and dermatitis. Corticosteroids are widely used as controller medications in the treatment of persistent asthma. Croup Also called laryngotracheitis, this is a viral condition that affects the subglottic tissue, resulting in swelling and obstruction of the airway. It is mainly caused by the parainfluenza virus. Its most notable characteristics are inspiratory stridor, low-grade fever, and seal-like, barky cough. Croup caused by a bacterial infection is called laryngotracheobronchitis, which is described as inflammation of the larynx, trachea, and bronchi, leading to airway obstruction.

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Cyanotic heart disease This is a heart condition that demonstrates car-

diac insufficiency and results in a bluish discoloration to the skin. It can be seen at birth or shortly after the birth. Infants born with a cyanotic heart disease will have some type of shunt (an opening to facilitate the body receiving some oxygen-enriched blood).

Cystic fibrosis This is an autoimmune hereditary genetic disorder lo-

cated on the chromosome 7 gene. This condition affects both males and females. CF affects the autonomic nervous system, causing an abnormal overproduction of secretions that interfere with normal body function. This overproduction of secretions can lead to tissue and organ damage, especially in the lungs and digestive tract.

Dexamethasone Also known by the trade name Decadron, this synthet-

ic glucocorticoid drug is used in the treatment of infants with chronic lung disease of the newborn and croup to help decrease inflammation of the airway.

Duchenne muscular dystrophy (DMD) Characterized by progressive

weakness in the lower extremities. The condition is found more often in male than females and is characterized by generalized weakness and muscle damage, most notably to the calf and leg muscles. The muscle tissue is replaced with fat and connective tissue, which causes the classic symptoms of frequent falls and difficulty getting up from a sitting position. DMD stems from a lack of dystrophin, a protein found in the smooth muscle lining of the stomach.

Endotracheal intubation This is a medical procedure in which a tube is inserted into the lumen of the trachea for the purpose of establishing an artificial airway. Epiglottitis This is described as an inflammation of the soft tissue surrounding the epiglottis, which causes a blockage of the trachea, thus preventing breathing. This condition, caused by Haemophilus influenzae type B bacterial infection, results in swelling of the supraglottic structures

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of the airway. Its most notable characteristics are rapid onset, high fever, muffled voice, no barky cough, and observation of the child in the tripod position.

Extracorporeal membrane oxygenation (ECMO) This type of therapy uses a modified heart-lung machine that provides for gas exchange in patients suffering from hypoxemic respiratory failure. The machine is an external device that oxygenates blood delivered to it from the body and then returns it to the patient.

Haemophilus influenzae type B vaccine A vaccine used in the treatment of epiglottitis. It is given to an infant beginning at 2 months of age. This vaccine has been shown to prevent epiglottitis. Heliox A therapeutic gas mixture of helium and oxygen that is com-

mercially available in three different mixtures: 80–20, 70–30, and 60–40.

Heliox administration The delivery of a therapeutic gas mixture of helium and oxygen. It is commonly used in the treatment of severe asthma exacerbation. Helium, a very light gas that can act as a carrier, has been shown to improve gas exchange in patients with asthma by lowering airway resistance, improving gas flow, and improving gas exchange. It has been shown to convert areas of turbulent flow within the airway to areas of laminar flow.

High-frequency oscillatory ventilation (HFOV) Pulmonary ventilation with multiple rapid breaths given at small tidal volumes. It limits the stretching and collapse of the alveoli that occur in conventional mechanical ventilation. Hyperoxia test Historically, this was a test used to determine the cause

of respiratory distress in the newborn: 100% oxygen was given to the patient to see whether he or she responded with a significant increase in PaO2. Failure to respond was seen as an indication of severe congenital heart disease.

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245

Infant respiratory distress syndrome Infant respiratory distress syn-

drome, also called hyaline membrane disease (HMD) or respiratory distress syndrome (RDS) of the newborn, is a condition caused by the absence of proper surfactant production due to an immature or poorly developed lung, which is typically seen in premature infants. In the postmature infants, IRDS is the result of disruption of airflow with subsequent atelectasis, causing an acute lung injury.

Inhaled nitric oxide Nitric oxide is a colorless, odorless gas that is rela-

tively insoluble in water and possesses some vasodilation properties on lung tissue. Inhaled nitric oxide has been shown to be effective as a pulmonary vasodilator in patients with pulmonary hypertension. Inhaled nitric oxide is Federal Drug Administration (FDA) approved in the treatment of infants with persistent pulmonary hypertension of the newborn (PPHN).

Ketamine This rapid-acting general anesthetic is commonly used in the treatment of severe asthma exacerbation.

Laryngeal edema This is the swelling of the larynx, usually from an allergic reaction and causing airway obstruction.

Lung protective strategy Lung protective strategies are used to minimize lung damage in patients suffering from acute lung injury or acute respiratory distress syndrome. Low tidal volume and permissive hypercapnia are examples of lung protective strategies. Magnesium sulfate This chemical compound can be used as a bronchodilator in the treatment of severe asthma exacerbation.

Mechanical ventilation Called positive pressure, mechanical ventilation is mechanical support that applies positive pressure to the patient’s airway through an artificial airway (endotracheal tube or tracheostomy tube) with the intent of improving pulmonary gas exchange, reversing acute respiratory failure, and reversing or preventing atelectasis.

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Mechanical ventilator This is a mechanical device for artificial ventila-

tion of the lungs. The mechanism is machine driven and automated. It is referred to as a conventional ventilator and drives positive pressure into the airway as a means of providing artificial ventilation.

Meningitis This is the inflammation of the membranes of the spinal cord or brain. Bacterial meningitis was largely seen in infants who were affected by Haemophilus influenzae. Since the introduction of the Haemophilus influenzae vaccine, bacterial meningitis is not seen as frequently in infants and children. Nebulized racemic epinephrine Nebulized racemic epinephrine is used in the treatment of croup. It is given as an inhaled medication. It facilitates a decrease in swelling around the airway. An adverse effect to racemic epinephrine is increased heart rate, or tachycardia.

Nebulizer therapy This type of therapy involves using a machine that produces a fine spray or mist. This is done by either rapidly passing air through a liquid or by vibrating a liquid at high speed to break down the particles into a very small size to be inhaled. A small volume nebulizer is most often used to deliver medications to the airway. Ultrasonic nebulizer is another device used to deliver medication to the airway. Noncyanotic heart disease A heart condition that may not result in cardiac insufficiency where patients may be asymptomatic for many years.

Noninvasive ventilation This is the application of positive pressure

ventilation without an artificial airway to the upper respiratory tract. Its purpose is to augment alveolar ventilation. Noninvasive ventilation is delivered through the use of a nasal or facial mask.

Obstructive sleep apnea Often referred to simply as sleep apnea, this is

the temporary cessation of breathing during sleep. It results from a blockage of the airway by soft tissue that prevents air from going in and out of the airway. This condition is characterized by loud snoring, grunting,

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snorting, or gasping. There are three classifications of sleep apnea: (1) obstructive sleep—respiratory efforts are made, but there is a blockage of the airway by soft tissue, (2) central sleep apnea—no respiratory efforts are made during sleep, and (3) mixed apnea—there is no respiratory effort made, followed by upper airway obstruction. Diagnosing sleep apnea is done in a sleep lab, where the patient undergoes a sleep apnea study to determine the extent of the sleep apnea.

Oxygen therapy The administration of oxygen at higher levels than are normally found in atmosphere (higher than 21%). It is given to patients who require higher levels of oxygen to meet the tissue’s metabolic demands. It can be administered by a nasal cannula (prongs that are placed in the nares), a venturi mask, a face mask, or a tracheostomy mask—all are devices that are placed over the mouth and nose of the patient—or it can be administered through a mechanical device such as a positive pressure ventilator with or without an artificial airway. Partial liquid ventilation Perfluorocarbon is a class of solvent molecules that can carry nonpolar gases, such as oxygen, nitrogen, and carbon dioxide. Partial liquid ventilation is a process that takes the normal lung functional residual capacity and replaces it with perfluorocarbon liquid. This is used to reduce surface tension in lungs that lack surfactant. Patent ductus arteriosus This is a congenital heart disease in which the ductus arteriosus fails to close shortly after birth. The ductus arteriosus is one of the three uterine shunts that allow blood to bypass the lungs. This shunt connects the aorta to the pulmonary artery which allows oxygenrich blood to pass from the mother to the fetus through the placenta. Within hours up to a week after the infant is born this shunt closes. Prone positioning Prone positioning is placing a patient on his or her

stomach to improve oxygenation. Used in the treatment of patients with ARDS, the prone position allows for better distribution of pulmonary blood flow to match pulmonary ventilation.

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Prostaglandin E1 This pulmonary vasodilator is a medication used to decrease the pulmonary blood pressure and facilitate blood flow through the lungs, where it picks up oxygen and sends it down to the body. Pulmonary interstitial emphysema A diffuse hazy opacity of the lungs

consistent with surfactant deficiency. It is described as solid linear or dotlike structures within air-filled cysts that differ in appearance from pulmonary emphysema. In this condition, free air travels throughout the tissues of the lungs.

Recruitment maneuver This treatment for patients with acute respiratory distress syndrome is any sustained application of high positive end expiratory pressure to the airway with the intent of decreasing the collapse of alveoli during mechanical ventilation. Respiratory failure This is a condition in which the patient needs me-

chanical ventilation. It can be categorized as acute or chronic. Acute respiratory failure is the impairment of oxygenation or ventilation in which the PaO2 falls below 60 mm Hg, the PaCO2 rises above 50 mm Hg, the patient is not a chronic CO2 retainer, and the pH is below 7.30. Patients with acute respiratory failure need immediate attention to optimize gas exchange. Chronic respiratory failure is the inability of the respiratory system to maintain the function of oxygenating the blood and removing CO2 from the lungs. Chronic respiratory failure is often associated with conditions like chronic obstructive pulmonary diseases.

Respiratory syncytial virus (RSV) This is a medium-sized RNA virus that

begins in the nasal epithelial cells, then replicates itself in the host cell, ultimately destroying the host cell, giving it the ability to reproduce in nearby uninfected cells. This virus can travel from cell to cell and easily spreads to the lower respiratory tract, where it does the most damage. RSV is the typical cause of children with bronchiolitis, which is an acute, highly infectious, lower respiratory tract infection.

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Ribavirin (Virazole) A type of medication used to treat patients with respiratory syncytial virus. It is delivered through a small particle aerosol generator (SPAG). Patients with chronic lung disease, cardiac defect, or patients who were immunosuppressed as with HIV or organ transplantation are candidates to receive this medication.

Saturation Also called oxygen saturation, this is a percentage of arterial hemoglobin that is saturated with oxygen. This measurement is typically seen with the use of a pulse oximeter attached to the patient. Small particle aerosol generator (SPAG) This unit was designed specifically to administer Ribavirin to patients with respiratory syncytial virus. Spinal muscular atrophy (SMA) This hereditary disease results in weakness and muscle wasting in the arms and legs of infants and children. The three types of SMA are determined by the age of onset and the symptoms involved. SMA is characterized by a missing gene, called the survival motor neuron gene, which is responsible for the production of protein necessary for the proper function of the motor neuron. Spontaneous pneumothorax In this condition, free air in the pleura spaces results from a weakening alveolar membrane.

Surfactant Surfactant is a pulmonary agent secreted by the type II alveolar cells that decreases surface tension of the fluid lining the lungs, permitting expansion of the alveoli, which results in gas exchange. Surfactant is commercially available and is used in surfactant replacement therapy for the treatment of patients with respiratory distress syndrome of the newborn. Synagis (palivizumab) A Food and Drug Administration (FDA) approved vaccine for the treatment of high-risk infants against the respiratory syncytial virus. High-risk infants include infants born prematurely (before 35 weeks), those with heart defects, and those who have chronic lung disease of the newborn. These infants may be particularly susceptible to

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getting lung infections. This vaccine is injected intramuscularly during the respiratory syncytial virus season every 28 to 30 days.

Tension pneumothorax This occurs when the lung tissue has already suf-

fered damages. It can occur as a result of scar tissue. Scar tissue tends to make the lung walls tight, which prevents air from entering; therefore, air that enters the lung parenchyma cannot escape, causing a buildup of pressure inside the lung walls. This pressure causes a shift in cardiac structures, which decreases venous return and decreases cardiac output. Tension pneumothorax is a medical emergency and must be relieved immediately.

Tetralogy of Fallot In this congenital heart defect, there is a combination of four abnormal heart structures: (1) ventricular septal defect—a hole between the walls of the ventricles, (2) narrowing of the pulmonary outflow tract, (3) an aorta that arises from the right and left ventricles, and (4) a thick muscular wall of the right ventricle. An infant born with tetralogy of Fallot may not show cyanosis immediately, but may develop cyanotic episodes later. Total anomalous pulmonary venous return A defect in which the pulmo-

nary veins are missing and blood is redirected back to the right atrium rich in oxygen, which means that there is no oxygen-rich blood going to the body. This is a life-threatening emergency requiring immediate attention.

Transillumination A procedure used in most nurseries to detect a pneumothorax at the bedside. A fiber optic light is placed on the chest to light up the chest wall. An increased amount of light might mean free air in the chest cavity. Transillumination is not used as a substitute for a chest x-ray. Transposition of the great vessels In this congenital defect, the two main arteries are connected to the wrong heart chambers. Here the aorta is connected to the right ventricle and the pulmonary artery is connected

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251

to the left ventricle. Infants born with transposition of the great vessels will have some other type of cardiac defect, such as an atrial septal defect, which will allow for the mixing of deoxygenated blood with some oxygenated blood. Infants with this defect require surgery usually within the first few weeks of life.

Tricuspid atresia A structural defect of the tricuspid valve. The valve is

either missing or broken, causing a blockage to pulmonary blood flow from the right atrium to the right ventricle through the pulmonary trunk to the lungs.

Ventricular septal defect This condition is characterized by one or more holes in the wall between the right and left ventricles. It is the most common congenital heart defect observed. Small ventricular septal defects can self-close and are asymptomatic. Large ventricular septal defects cause too much blood to be pumped to the lungs, which leads to congestive heart failure.

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Index

A Acapella valve, 112, 113 Acquired heart disease, 208 Acute lung injury (ALI), 2, 8–9 criteria chain for, 2 treatment for, 13–32 Acute respiratory distress syndrome (ARDS), 1–35, 211 characteristics of, 3 clinical case review, 4–5 clinical signs of, 3 congestive heart failure versus, 4 conventional mechanical ventilation, 13, 15–17 criteria chain for, 1 defined, 2–3 extracorporeal membrane oxygenation, 28–30 heliox administration, 30 inhaled nitric oxide, 22–26 mortality rate of, 9 oxygen, 20 partial liquid ventilation, 30–32 prone patient positioning, 26–28 research on, 8–13 respiratory therapist initial response, 5–8 treatment for, 13–32 ventilation, 20–22 vital signs and, 5 Adenovirus, 134 Adult respiratory distress syndrome, 9 Advair, 115 Aerobid, 116 African Americans asthma in, 58 cystic fibrosis and, 104 Air leak syndromes, 149–85 characteristics of, 154–61 chest x-rays and, 161–62 defined, 151–54 distinguishing, 161–62 high-frequency jet ventilation, 164–68 high-frequency oscillator ventilation for, 174–77 oxygen, 178 pneumomediastinum, 153, 159

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pneumopericardium, 154, 159 pneumothorax, 151–52, 154–55 pulmonary interstitial emphysema, 154, 160–61 research on, 162–63 treatment for, 163–83 ventilation, 178–79, 183 Airway edema, 59 normal versus abnormal, 57 Airway clearance therapies, 113 Airway pressure release ventilation (APRV), 14, 15, 16 Albuterol, 99 for bronchiolitis, 139–40 for cystic fibrosis, 114, 115 Allergens, 83 American Academy of Pediatrics (AAP), 150, 200, 207, 216 American College of Chest Physicians (ACCP), 110 recommendations for airway clearance therapies, 113 American European Consensus Conference (AECC), 2, 9 American Heart Association, 188, 191 American Thoracic Society (ATS), 226, 228, 236 Andersen, Dorothy, 104, 107 Antenatal steroids, 92 Antibiotics for chronic lung disease of the newborn, 98, 99 for cystic fibrosis, 114, 116 Anticholinergic, 82 for chronic lung disease of the newborn, 99 Anti-inflammatory medications, for cystic fibrosis, 114 ARDS Clinical Research Network (ARDSnet), 9, 11 Arterial blood gas collection, 69 Asian Americans, cystic fibrosis and, 104 Assisted coughing, 228 Asthma, 55–85 anticholinergic for, 82

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Index

arterial blood gas collection, 69 bronchiolitis versus, 136 causes of, 59 characteristics of, 62–63 chronic lung disease of the newborn versus, 90 clinical presentation of, 58–59 cockroaches and, 61 corticosteroids for, 82 defined, 56–58 delivery devices for, 69–83 drug dosages for management of, 73–74 drugs for, 82–83 dust mites and, 61 healthcare costs for, 58 helium-oxygen therapy, 78–82 impairment reduction, 68 NAEPP guidelines for severe exacerbations, 70 oxygen therapy, 69 patient presentation for, 84 population affected by, 57–58 research on, 63–69 risk reduction, 69 severe asthma exacerbation versus, 60 severe exacerbation, 57 severity, 61–62 short-acting beta 2 -agonist (SABA), 72, 75 signs and symptoms of, 60 smoking and, 63 treatment of, 69–83 triggers, 59 Atrial septal defect (ASD), 191, 193, 198–200 characteristics of, 204–5 ostium primum defect, 205 ostium secundum defect, 205 sinus venosus defect, 205 symptoms of, 205 treatment of, 214 Atrovent, 115 Azmacort, 116 B Bacteremia, 136 Bacterial endocarditis, 208–9 Bacterial tracheitis, bronchiolitis versus, 136–37 Bag mask device, 158 Ball-valve mechanism, 42 Barotrauma, 145, 150 Beclomethasone (QVAR), 116 Bias flow, 20, 178, 180

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Bronchiectasis, cystic fibrosis versus, 106 Bronchiolitis, 90, 123, 133–48 asthma versus, 136 bacterial tracheitis versus, 136–37 bronchodilators, 139–40 characteristics of, 135–36 croup versus, 137 defined, 134–35 delivery devices for, 141–43 heliox for, 143, 144 mechanical ventilation for, 144–46 population affected by, 135–36 research on, 137–38, 138–46 respiratory diseases versus, 136–37 symptoms for, 135 Synagis, 139 Bronchitis, cystic fibrosis versus, 106 Bronchoconstriction, 58 Bronchodilators albuterol, 139 for bronchiolitis, 139–40 for cystic fibrosis, 114 racemic epinephrine, 140 short-acting, 97–98 therapy, 138 Xopenex, 139 Bronchopulmonary dysplasia (BPD), 166 Budesonide, 116, 125, 126 Bunnell, J. Bert, 164 C Cardiac defects mechanical ventilation with, 210 surgical treatment for, 213 Cardiac tamponade, 160 Cardiomyopathy, 208–9 Centers for Disease Control and Prevention (CDC), 105, 225 Chanock, Robert, 137 Chest physiotherapy, for cystic fibrosis, 114 Chest x-rays, 161–62 Choanal atresia, 46 Chronic lung disease of the newborn (CLD), 87–101 characteristics of, 88–90 chronic respiratory illnesses versus, 90 defined, 88 drug dosages for, 99 nutritional support for, 93 nutrition strategy for, 98–100 pharmacology therapy for, 93, 97–98 population affected by, 88

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prevention, 92 research on, 90–92 signs of, 89 stages of, 89–90 treatment for, 92–100 ventilator and oxygen strategy, 92, 96–97 ventilator management for, 96–97 Chronic obstructive pulmonary disease (COPD), 88 Cigarette smoking, asthma and, 63 Circulation, normal fetal, 189 Coarctation of the aorta, 201–2 characteristics of, 206 symptoms of, 206–7 treatment of, 215–16 Cochrane Collaboration, 32 Cockroaches, asthma and, 61 Combivent, 115 Computer tomography (CT), 163 Congenital diaphragmatic hernia (CDH), 38, 40, 43, 45 treatment for, 52 Congenital heart disease, 187–218 acquired heart disease and, 208 characteristics of, 202–7 defined, 191–202 distinguishing, 207–9 noncyanotic heart disease, 198–202 research on, 209–10 tetralogy of fallot, 191, 192, 202–3, 211 total anomalous pulmonary venous return, 195, 198, 199, 204, 213–14 transposition of great vessels, 191–95, 203, 211–12 treatment for, 211–16 tricuspid atresia, 195, 197, 203–4, 212–13 Congenital muscular dystrophy, 223–24 Congestive heart failure (CHF), 188, 207–8 symptoms of, 207–8 treatment of, 216 Continuous nebulizer, 78, 79 therapy with SABA, 75–77 Continuous positive airway pressure (CPAP), 15, 47, 48, 96 Conventional mechanical ventilation, for acute respiratory distress syndrome, 13, 15–17 Conventional ventilation, 164 with high-frequency oscillator ventilation, 176 Conventional ventilation (CV), 175 Corticosteroid anti-inflammatory drugs, 116

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255

Corticosteroids, 82 for chronic lung disease of the newborn, 98 for upper airway inflammatory diseases, 126 Coughlator, 234–36 Croup, 120, 130 bronchiolitis versus, 137 epiglottitis versus, 121 steeple sign in, 124 steroid therapy for, 123 treatment for, 127 Cyanotic heart diseases, 188, 217 characteristics of, 202–4 Cystic fibrosis (CF), 103–18 characteristics of, 105–6 chest physiotherapy, 114 defined, 104–5 discovery of, 104 high-frequency chest wall oscillation, 110, 111 lung transplantation and, 109 manual chest physiotherapy for, 110 medications for, 114 nutritional support, 114 pancreatic enzyme replacement therapy, 114 population affected by, 104–5 pulmonary illnesses versus, 106–7 research on, 107–9 respiratory therapy, 109–13 signs and symptoms of, 106 surgical options, 114 treatment for, 109–16 vibratory devices, 110 Cystic fibrosis transmembrane conductance regulator (CFTR) gene, 104 D Delivery devices for bronchodilators, 141–43 meter dose inhaler, 141 ribavirin, 142–43 small volume nebulizer, 141 Dexamethasone, 125, 126 Diphtheria, 120 Diuretics, for chronic lung disease of the newborn, 98, 99 Dosage for asthma management, 73–74 for treatment of chronic lung disease of the newborn, 99

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256

Index

Duchenne, Guillaume, 221 Duchenne muscular dystrophy (DMD), 220, 221 characteristics of, 222–23 spinal muscular atrophy versus, 224 treatment of, 227–36 Ductus arteriosus, 190 Ductus venosus, 190 Duoneb, 115 Dust mites, asthma and, 61 E Epiglottitis, 120, 130 croup versus, 121 historical facts about, 125 thumb sign and, 122 treatment for, 127, 129 Exposure to tobacco smoke (ETS), 63 Extracorporeal membrane oxygenation (ECMO), 14, 23, 28–30, 48, 51 diagram of, 29 inclusion criteria for, 30 F Federal Drug Administration (FDA), 107 Flovent, 116 Flutter valve, 111 Food and Drug Administration (FDA), 175 Foramen ovale, 190 Foreign-body airway obstruction (FBAO), 122 Frequency, in ventilation, 20–21, 178–79 Fundamentals of Respiratory Care (Egan), 2, 6 G Gastroesophageal reflux (GERD), 62, 63 chronic lung disease of the newborn versus, 90 Graft, 216 Group B streptococcus (GBS), 44 H Haemophilus influenzae type B, 120, 126, 130 Heart formation of structures, 190 normal fetal circulation, 189 Heated, humidified high flow nasal cannula, 93 Heliox administration, 14, 30 with mechanical ventilation, 32 with nebulizer, 31 Helium-oxygen therapy (heliox therapy), 78–82

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for bronchiolitis, 143, 144 mask, 81 High flow oxygen and aerosol therapy, 93 High-frequency chest wall oscillation, 110, 111 High-frequency chest wall oscillatory vest, 229 High-frequency jet ventilation (HFJV), 22, 23, 47, 48, 164–68 calibration of, 173 with iNO, 25, 26 jet box, 168 optimal PEEP during, 172 settings, 167 steps for, 169–71 troubleshooting, 173–74 High-frequency oscillator ventilation (HFOV), 14, 17–20, 21, 47, 48, 164 for air leak syndromes, 174–77 conventional ventilation and, 176 face panel, 177 operation of, 19–20, 175–77 starting settings, 180 troubleshooting, 181–83 High heated humidity nasal cannula, 49 High humidity nasal cannula, 95 Hourglass sign. See Steeple sign Human metapneumovirus, 134 Humidity therapy, for upper airway inflammatory diseases, 126, 127 Hyaline membrane disease (HMD), 39, 41, 45 Hyperinsufflation therapy, 234–36 Hypersensitivity, 58 Hypertonic saline, 116 Hypoxemia, 12 I Infant Flow device, 49 Infant respiratory distress syndrome (IRDS), 37–54 characteristics of, 41–44 clinical note on, 40 conditions that mimic, 44–46 defined, 38–41 research on, 46–48 symptoms of, 41–42 treatment, 48–51 Influenza, 134 Inhaled nitric oxide (iNO), 14, 22–26, 48, 51 conventional ventilator with, 24 high-frequency jet ventilation with, 25, 26

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Inhaled steroids, for chronic lung disease of the newborn, 99 Inspiratory time, in ventilation, 21, 179 Intermittent positive pressure breathing machine (IPPB), 228 Intrapulmonary percussive ventilation (IPV), 112, 113, 114, 228, 234 Invasive inflation, 236 Irritants, 83 J Johns Hopkins University Children’s Heart Center, 213 L Laryngotracheobronchitis (LTB), 121 Laryngotracheobronchopneumonitis (LTBP), 121 LifePulse, 164, 165, 166, 168, 169–71 calibration of, 173 troubleshooting, 173–74 Low birth weight infants, chronic lung disease of the newborn and, 91 Low flow nasal cannula, 93 Lung recruitment maneuver, 17 Lung transplantation, cystic fibrosis and, 109 Lung whiteout, 90 M Manual chest physiotherapy, 108, 110, 231–33 for neuromuscular diseases, 228 Manual percussor, 230 Mean airway pressure, 20, 178, 180 Mechanical percussor, 230 Mechanical ventilation for bronchiolitis, 144–46 with cardiac defects, 210 with heliox, 32 initial settings for, 8 settings for, 146 Mechanical ventilators, 83, 93 Meconium aspiration syndrome (MAS), 38, 39–40, 42, 45, 151 signs of, 42–43 treatment for, 52 Meningitis, 136 Merosin, 224 Metered dose inhaler (MDI) for bronchiolitis, 141 Mist tent, 127

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Index

257

Mucolytics, for cystic fibrosis, 114, 115–16 Mucomyst, 115 Muscular Dystrophy Association, 223 Myasthenia gravis, 46 congenital, 46 neonatal, 46 Myocarditis, 208–9 N Nasal cannula, 93, 141 high flow, 142 neonatal, 94 pediatric, 94 National Asthma Education and Prevention Program (NAEPP), 56, 62, 63, 68 drug dosages for management, 73–74 stepwise chart, 64–67 National Center for Healthy Housing (NCHH), 68 National Heart, Lung, and Blood Institute (NHLBI), 9, 11, 88, 91 National Institute of Neurological Disorders and Stroke (NINDS), 220 National Institutes of Health (NIH), 9, 38 National Survey on Environmental Management of Asthma, 63 Nebulizer for chronic lung disease of the newborn, 99 continuous, 78, 79 heliox administration with, 31 small volume, 77 units, 80 Needle aspiration, 160 Neonatal nasal cannula, 94 Neonatal pneumonia, 44 Neuromuscular diseases, 219–38 characteristics of, 221–23 congenital muscular dystrophy, 223–24 defined, 220–21 distinguishing, 223–24 Duchenne muscular dystrophy, 220, 221 research on, 225–27 spinal muscular atrophy, 220–21 treatment of, 227–36 NICU respiratory therapists, 44 Noncyanotic heart disease, 198–202 atrial septal defect, 198–200, 204–5, 214 characteristics of, 204–7 coarctation of the aorta, 201–2, 206–7, 215–16

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258

Index

Noncyanotic heart disease (Cont.) patent ductus arteriosus, 200–201, 206, 215 ventricular septal defect, 200, 205–6, 214–15 Noninvasive positive pressure ventilation (NIPPV), 71, 226, 236 Nonsteroidal anti-inflammatory medications, for chronic lung disease of the newborn, 98, 99 Nutritional support for chronic lung disease of the newborn, 93, 98–100 for cystic fibrosis, 108 O Ostium primum defect, 205 Ostium secundum defect, 205 Oxygen, 20 for air leak syndromes, 178 bias flow, 20 blenders, 20, 178 mean airway pressure, 20 therapy, 69, 92, 93 P Palivizumab. See Synagis Pancreatic enzyme replacement therapy, 114 Pancreatitis, cystic fibrosis versus, 107 Parainfluenza, 134 Parainfluenza virus, 137 Paramyxovirus, 134 Partial liquid ventilation (PLV), 14, 30–32 Patent ductus arteriosus (PDA), 200–201 characteristics of, 206 symptoms of, 206 treatment of, 215 Pediatric mask, 76 Pediatric nasal cannula, 94 Pediatric nonrebreather mask, 71 Pentamidine, 116 Percussor manual, 230 mechanical, 230 Perfluorocarbon liquid, 30 Pericarditis, 208–9 Perinatal asphyxia, 44 Persistent pulmonary hypertension of the newborn (PPHN), 22, 38, 40, 45 transition, 43 treatment for, 52

5467 Book.indb 258

Pharmacology strategy, for chronic lung disease of the newborn, 93, 97–98 antibiotics, 98 corticosteroids, 98 diuretics, 98 nonsteroidal anti-inflammatory medications, 98 short-acting bronchodilators, 97–98 Physical conditions, asthma and, 83 Pierre Robin syndrome, 46 Pneumomediastinum, 153, 161 characteristics of, 159 treatment for, 163 Pneumopericardium, 154, 161 characteristics of, 159–60 treatment for, 163 Pneumothorax, 151–52 case study, 156–59 characteristics of, 154–55 ongoing assessments for, 157 signs of symptoms of, 156 spontaneous, 151, 152, 161 tension, 151–52, 161 treatment for, 163 Positive end-expiratory airway pressure (PEEP), 2, 10, 11, 14, 15, 17, 40, 154, 172 Positive expiratory pressure (PEP), 110, 111 Positive inspiratory pressure (PIP), 154 Positive pressure ventilation, for upper airway inflammatory diseases, 127, 129 Power, in ventilation, 21, 179 Pressure control ventilation (PCV), 14 Pressure support ventilation (PSV), 97 Prone patient positioning, 26–28 contraindication for, 28 patient placement, 27–28 preparing patient for, 27 Prone positioning, 14 Prostaglandin E, 212 Pseudomonas aeruginosa, 107, 108 Pulmicort. See Budesonide Pulmonary air embolism, 151 Pulmonary interstitial emphysema (PIE), 151, 154, 161–62, 163 characteristics of, 160–61 treatment for, 164 Pulmonary vascular resistance (PVR), 40 Pulmozyme, 107, 115 R Racemic epinephrine, 129 for bronchiolitis, 140

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Research on acute respiratory distress syndrome, 8–13 on air leak syndromes, 162–63 on asthma, 63–69 on bronchiolitis, 137–38, 138–46 on chronic lung disease of the newborn, 90–92 on congenital heart disease, 209–10 on cystic fibrosis, 107–9 on infant respiratory distress syndrome, 46–48 on neuromuscular diseases, 225–27 on upper airway inflammatory diseases, 123–26 Respiratory distress syndrome (RDS), 39, 88–89, 151 conditions affecting, 45 treatment, 51 Respiratory syncytial virus (RSV), 89, 123, 134, 137, 138 Respiratory therapist, acute respiratory distress response and, 5–8 Respiratory therapy, for cystic fibrosis, 109–13 Respiratory treatment, for cystic fibrosis, 114–16 Rhinovirus, 134 Ribavirin, 142–43 S Servo 300, 82 Servo i, 82 Short-acting beta 2 -agonist (SABA), 72, 75 continuous nebulizer therapy with, 75–77 Sinusitis, cystic fibrosis versus, 106 Sinus venosus defect, 205 Small particle aerosol generator (SPAG), 142, 143 Small volume nebulizer (SVN), for bronchiolitis, 141 Spinal muscular atrophy (SMA), 220–21 characteristics of, 221–22 Duchenne muscular dystrophy versus, 224 phenotype, 223 treatment of, 227–36 Spiriva, 115 Spontaneous pneumothorax, 151, 152, 161 Staphylococcus aureus, 209 Steeple sign, 123, 124 Steroid therapy, for croup, 123 Streptococcus pneumoniae, 209

5467 Book.indb 259

Index

259

Subcutaneous emphysema, 151 Suction, 22 Surfactant replacement therapy (SRT), 12, 48, 51 Synagis, 139 T Tension pneumothorax, 151–52, 161 Tetralogy of Fallot, 191, 192 characteristics of, 202 symptoms of, 202–3 treatment of, 211 Tidal volumes, 15, 165 Tobramycin, 116 Total anomalous pulmonary venous return (TAPVR), 195, 198, 199 characteristics of, 204 symptoms of, 204 treatment of, 213–14 Tracheal deviation, 155 Tracheoesophageal fistula, 46 Tracheostomy collar, 95 Transient tachypnea of the newborn (TTN), 38, 39, 42, 45, 151 risk factors for, 39 treatment for, 52 Transillumination, 155 Transposition of the great vessels (TGV), 191–95, 196 characteristics of, 203 symptoms of, 203 treatment of, 211–12 Treatment for acute respiratory distress syndrome, 13–32 for air leak syndromes, 163–83 for asthma, 69–83 for chronic lung disease of the newborn, 92–100 for congenital diaphragmatic hernia, 52 for congenital heart disease, 211–16 for cystic fibrosis, 109–16 for infant respiratory distress syndrome, 48–51 for meconium aspiration syndrome, 52 for neuromuscular diseases, 227–36 for persistent pulmonary hypertension of the newborn, 52 for transient tachypnea of the newborn, 52 for upper airway inflammatory diseases, 126–29

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260

Index

Tricuspid atresia, 195, 197 characteristics of, 203–4 symptoms of, 204 treatment of, 212–13 Troubleshooting high-frequency jet ventilation, 173–74 high-frequency oscillator ventilation (HFOV), 181–83 U Upper airway inflammatory diseases, 119–31 bronchiolitis, 123 characteristics of, 120–22 croup, 120 defined, 120 epiglottitis, 120 foreign-body airway obstruction, 122 research on, 123–26 treatment for, 126–29 U.S. National Library of Medicine, 38 Uterine shunt closures, 190 V Vapotherm device, 49, 50, 96 Ventilation, 20–22 for air leak syndromes, 178–79, 183 conventional, 164, 175 frequency, 20–21, 178–79 inspiratory time, 21, 179

5467 Book.indb 260

mechanical, 32, 144–46 power, 21, 179 Ventilator and oxygen strategy, for chronic lung disease of the newborn, 92, 96–97 Ventilator management, 96–97 Ventilators for air leak syndromes, 164 conventional, with iNO, 24 mechanical, 83, 93 Ventricular septal defect (VSD), 191, 194, 200 characteristics of, 205 symptoms of, 205–6 treatment of, 214–15 Vibratory devices, 110 Virazole. See Ribavirin Vital signs, acute respiratory distress syndrome and, 5 Vocal cord dysfunction, asthma and, 62 Volume guarantee (VG), 97 W Werdnig-Hoffman disease, 45, 222 Wohlfart-Kugelberg-Welander syndrome, 222 X Xopenex, 114 for bronchiolitis, 139–40

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Credits

Chapter 1 1-2 Courtesy of © Dräger Medical AG & Co. KG, Lübeck, Germany; 1-3 Courtesy of CareFusion, Yorba Linda, California; 1-4 Courtesy of Bunnell Incorporated; 1-6 Modified from a photo courtesy of CareFusion, Yorba Linda, California; 1-8 Courtesy of Jessica Hopkins, University of the District of Columbia, College of Arts and Science, Studio Art; 1-9 Courtesy of Elgloria Harrison, University of the District of Columbia

Chapter 2 2-1 Courtesy of Elgloria Harrison, University of the District of Columbia; 2-2 Courtesy of Vapotherm, Inc.

Chapter 3 3-2, 3-3, 3-4 Adapted from: National Asthma Education and Prevention Program Expert Panel Report 3, Guidelines for the Diagnosis and Management of Asthma. US Department of Health and Human Services, National Institutes of Health, National Heart, Lung, and Blood Institute, NIH Publication Number 08-5846, October, 2007; 3-5 Courtesy of Elgloria Harrison, University of the District of Columbia; 3-6 Courtesy of Philips Respironics, Murrysville, PA; 3-7 Adapted from: National Asthma Education and Prevention Program Expert Panel Report 3, Guidelines for the Diagnosis and Management of Asthma.

55461_ch13_CRED_5467.indd 261

US Department of Health and Human Services, National Institutes of Health, National Heart, Lung, and Blood Institute, NIH Publication Number 08-5846, October, 2007; 3-8 Courtesy of CareFusion Corporation or one of its subsidiaries; 3-9 Courtesy of Monaghan Medical Corporation; 3-10, 3-11 Courtesy of Elgloria Harrison, University of the District of Columbia; 3-12 Courtesy of Westmed, Inc.; 3-13 Courtesy of CareFusion Corporation or one of its subsidiaries

Chapter 4 4-1, 4-2, 4-3, 4-4 Courtesy of Elgloria Harrison, University of the District of Columbia

Chapter 5 5-1 The Vest ® Airway Clearance System is a registered trademark of Hill-Rom Services, Inc. © 2009 Hill-Rom Services, Inc. REPRINTED WITH PERMISSION-ALL RIGHTS RESERVED; 5-2 Courtesy of Axcan Pharma Inc.; 5-3, 5-4 Courtesy of Smiths Medical; 5-5 Courtesy of Percussionaire Corporation

Chapter 6 6-1 Courtesy of David Paulk, Arcadia University; 6-2 Courtesy of Hugh Dainer, MD, PhD; 6-3 Courtesy of Nova Health Systems, Inc.; 6-4A, 6-4B Courtesy of Elgloria Harrison, University of the District of Columbia

9/28/09 12:00:05 PM

262

Credits

Chapter 7

Chapter 10

7-1 Courtesy of Elgloria Harrison, University of the District of Columbia; 7-2, 7-3 © Jones and Bartlett Publishers. Courtesy of MIEMSS; 7-4 Courtesy of Elgloria Harrison, University of the District of Columbia; 7-5 Courtesy of Valeant Pharmaceuticals; 7-6 Courtesy of Jessica Hopkins, University of the District of Columbia, College of Arts and Science, Studio Art

10-1 The Vest ® Airway Clearance System is a registered trademark of Hill-Rom Services, Inc. © 2009 Hill-Rom Services, Inc. REPRINTED WITH PERMISSION-ALL RIGHTS RESERVED; 10-2A Courtesy of General Physiotherapy, Inc.; 10-3 Courtesy of Jessica Hopkins, University of the District of Columbia, College of Arts and Science, Studio Art; 10-4 Courtesy of Percussionaire Corporation; 10-5 Courtesy of Philips Respironics, Murrysville, PA; 10-2B Courtesy of Smiths Medical; 10-2C © 1999 KimberlyClark Worldwide, Inc. Used with permission

Chapter 8 8-4, 8-5 Courtesy of Elgloria Harrison, University of the District of Columbia; 8-7, 8-8, 8-9 Courtesy of Bunnell Incorporated; 8-10 Courtesy of Elgloria Harrison, University of the District of Columbia; 8-T03 Courtesy of Bunnell Incorporated; 8-11, 8-12 Courtesy of CareFusion, Yorba Linda, California

Unless otherwise indicated, all photographs and illustrations are under copyright of Jones and Bartlett Publishers, LLC.

Chapter 9 9-1, 9-2, 9-3, 9-4, 9-5, 9-6, 9-7 Courtesy of Jessica Hopkins, University of the District of Columbia, College of Arts and Science, Studio Art

5467 Book.indb 262

9/28/09 11:57:06 AM

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