Management of Obstructive Sleep Apnea
Management of Obstructive Sleep Apnea Edited by
Jonas T Johnson
MD, FACS
Department of Otolaryngology and Radiation Oncology University of Pittsburgh School of Medicine Pittsburgh, PA, USA
Jack L Gluckman
MD, FACS
Department of Otolaryngology University of Cincinnati Medical Center Cincinnati, OH, USA
Mark M Sanders
MD, FCCP, FABSM
Pulmonary Sleep Program Department of Pulmonary, Allergy and Critical Care Medicine University of Pittsburgh School of Medicine Pittsburgh, PA, USA Foreword by
Robert Ritch
MD
Chief Glaucoma Service The New York Eye and Ear Infirmary New York USA
Martin Dunitz
© 2002 Martin Dunitz Ltd, a member of the Taylor & Francis Group First published in the United Kingdom in 2001 by Martin Dunitz Ltd, The Livery House, 7–9 Pratt Street, London NW1 0AE Website: http://www.dunitz.co.uk Tel.: +44 (0) 20 7482-2202 Fax.: +44 (0) 20 7267-0159 E-mail:
[email protected] This edition published in the Taylor & Francis e-Library, 2002. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior permission of the publisher or in accordance with the provisions of the Copyright, Designs and Patents Act 1988 or under the terms of any licence permitting limited copying issued by the Copyright Licensing Agency, 90 Tottenham Court Road, London W1P 0LP. Although every effort has been made to ensure that all owners of copyright material have been acknowledged in this publication, we would be glad to acknowledge in subsequent reprints or editions any omissions brought to our attention. Although every effort has been made to ensure that drug doses and other information are presented accurately in this publication, the ultimate responsibility rests with the prescribing physician. Neither the publishers nor the authors can be held responsible for errors or for any consequences arising from the use of information contained herein. For detailed prescribing information or instructions on the use of any product or procedure discussed herein, please consult the prescribing information or instructional material issued by the manufacturer. A CIP record for this book is available from the British Library. ISBN 1 901865 96 7 (Print Edition) Distributed in the USA by Fulfilment Center Taylor & Francis 7625 Empire Drive Florence, KY 41042, USA Toll Free Tel.: +1 800 634 7064 E-mail: cserve@routledge–ny.com Distributed in Canada by Taylor & Francis 74 Rolark Drive Scarborough, Ontario M1R 4G2, Canada Toll Free Tel.: +1 877 226 2237 E-mail: tal–
[email protected] Distributed in the rest of the world by ITPS Limited Cheriton House North Way Andover, Hampshire SP10 5BE, UK Tel.: +44 (0) 1264 332424 E-mail:
[email protected] ISBN 0-203-42894-3 Master e-book ISBN
ISBN 0-203-44980-0 (Adobe eReader Format)
Contents Contributors
vii
Preface
ix
Acknowledgements
xi
I
Diagnostic considerations
1
Obstructive sleep apnea: the syndrome Steven M Koenig and Paul Suratt
2
3
4
II 5
Non-apneic causes of excessive daytime sleepiness Mark W Mahowald Obstructive sleep apnea in children Carole L Marcus
6
Therapy with oral appliances 111 Wolfgang Schmidt-Nowara
7
Nasal obstruction and nasal surgery David L Steward, Jack Gluckman and Jonas T Johnson
3
21
41
Diagnostic studies for sleep apnea/hypopnea 55 Rajesh Jasani, Mark H Sanders and Patrick J Strollo
121
8
Tracheotomy Jonas T Johnson and Jack Gluckman
9
Uvulopalatopharyngoplasty Aaron E Sher
145
10 Laser uvulopalatopharyngoplasty B Tucker Woodson
155
11 Hypopharyngeal airway surgery Kasey K Li and Nelson B Powell
137
175
Therapy Medical therapy Richard B Berry
81
12 Skeletal facial corrections Walter Hochban
185
vi
Contents
III Future advances 13 Radiofrequency tissue reduction 205 Jonas T Johnson and Jack Gluckman 14 Hypoglossal nerve stimulation Lennart Knaack and Walter Hochban
211
15 Serotonergic medications Richard B Berry
223
Index
235
Contributors Richard B Berry Sleep Laboratory Malcolm Randall VA Medical Center and Pulmonary and Critical Care Division University of Florida Health Science Center Box 100225 Gainesville, FL 32610-0225, USA Jack Gluckman Department of Otolaryngology University of Cincinnati Medical Center P0 Box 670528 Cincinnati, OH 45267-0528, USA Walter Hochban Mund-, Kiefer-, Gesichtschirurgie Schuetzenstrasse 84 D-78315 Radolfzell/Bodensee, Germany Rajesh Jasani Pulmonary Sleep Disorders Program Pulmonary, Allergy and Critical Care Medicine University of Pittsburgh Medical Center Montefiore University Hospital 3459 Fifth Avenue, 12-North Pittsburgh, PA 15213, USA Jonas T Johnson Department of Otolaryngology and Radiation Oncology University of Pittsburgh School of Medicine The Eye and Ear Institute Building 203 Lothrop Street, Suite 500 Pittsburgh, PA 15213, USA
Lennart Knaack Zentrum für Schlafmedizin Dortmund Hermanstrasse 48–52 D-44263 Dortmund–Hörde, Germany Steven M Koenig Pulmonary Division University of Virginia School of Medicine Box 800546 Charlottesville, VA 22908-0546, USA Kasey K Li Stanford Sleep Disorders Clinic and Research Center 750 Welch Road, Suite 317 Palo Alto, CA 94304, USA Mark W Mahowald Minnesota Regional Sleep Disorders Center Hennepin County Medical Center 701 Park Avenue Minneapolis, MN 55415, USA Carole L Marcus Division of Pediatric Pulmonology Park 316 Johns Hopkins Hospital 600 N. Wolfe Street Baltimore, MD 21287-2533, USA Nelson B Powell Stanford Sleep Disorders Clinic and Research Center 750 Welch Road, Suite 317 Palo Alto, CA 94304, USA
viii
Contributors
Mark H Sanders Pulmonary Sleep Disorders Program Pulmonary, Allergy and Critical Care Medicine University of Pittsburgh Medical Center Montefiore University Hospital 3459 Fifth Avenue, 12-North Pittsburgh, PA 15213, USA
Patrick J Strollo Jr Pulmonary Sleep Disorders Program Pulmonary, Allergy and Critical Care Medicine University of Pittsburgh Medical Center Montefiore University Hospital 3459 Fifth Avenue, 12-North Pittsburgh, PA 15213, USA
Wolfgang Schmidt-Nowara University of Texas Southwestern Medical School University of New Mexico and Sleep Medicine Institute Presbyterian Hospital Dallas 8140 Walnut Hill Lane, Suite 100 Dallas, TX 75231, USA
Paul Suratt Pulmonary Division University of Virginia School of Medicine Box 800546 Charlottesville, VA 22908-0546, USA
Aaron E Sher 6 Executive Park Drive Entrance C Albany, NY 12203, USA David L Steward Department of Otolaryngology University of Cincinnati Medical Center P0 Box 670528 Cincinnati, OH 45267-0528, USA
B Tucker Woodson Department of Otolaryngology and Communication Sciences Medical College of Wisconsin 9200 W. Wisconsin Avenue Milwaukee, WI 53226, USA
Preface It is interesting to observe that just twenty-five years ago snoring and obstructive sleep apnea were largely unrecognized and ignored by organized medicine. In the space of just a quarter of a century, a phenomenal ‘new’ field of medicine has developed which greatly impacts quality of life and carries the potential to change our perspective on risk for cardioand cerebrovascular disease. It is estimated that as many as 40% of the population experience socially unacceptable snoring. A significant proportion of these patients have associated sleep-disordered breathing, such as obstructive sleep apnea. The costs in terms of human suffering, social and medical morbidity and mortality, and healthcare, as well as productivity, expense are clearly enormous. Clinicians have not yet fully standardized diagnostic criteria for obstructive sleep apnea,
and efforts to develop evidence-based criteria are ongoing. Therapeutic decision making continues to challenge most physicians and their patients. This textbook attempts to address the current state of the art of the diagnosis and management of snoring and obstructive sleep apnea. The therapeutic use of oral appliances and a variety of surgical procedures indicate the dilemma every patient and treating physician must face in selecting appropriate intervention. Our section on future advances represents but the ‘tip of the iceberg.’ Every primary care physician should be alert to the signs and symptoms of the syndrome of obstructive sleep apnea. Professionals interested in this field must of necessity continue to challenge the past in an effort to improve the future. JTJ JG MHS
Acknowledgements This textbook on the Management of Obstructive Sleep Apnea is dedicated to our many professional colleagues who have contributed so much to our understanding of the diagnosis and treatment of sleep
disordered breathing. We pay special tribute to the thousands of patients who have willingly participated in our ongoing efforts to better understand this syndrome and its therapies.
I
Diagnostic considerations
1 Obstructive sleep apnea: the syndrome Steven M Koenig and Paul Suratt
Epidemiology
Genetics
Obstructive sleep apnea (OSA) was once thought to be an uncommon disorder. However, a recent community-based study estimated that, among randomly chosen middle-aged working adults, sleep-disordered breathing, defined as an apnea-hypopnea score (number of apneas plus hypopneas per hour of sleep) greater than or equal to 5, was found in 9% of women and 24% of men. Moreover, 2% of women and 4% of men met minimal criteria for OSA syndrome, defined as an apnea–hypopnea score of 5 or higher with daytime hypersomnolence.1 In the elderly, estimates of OSA frequency are even greater, ranging from 28% to 67% in men and from 20% to 54% in women.2–5 The prevalence of OSA syndrome in commercial truck drivers has been reported to be as high as 46%.6 In the USA, 20–30% of hypertensive patients have unrecognized sleep apnea.7 Overall, it is estimated that 18 million Americans suffer from OSA syndrome and that the cost of OSA is approximately $42 million annually from hospitalization alone.8 Particularly concerning is the fact that up to 95% of cases of OSA are unsuspected.8
OSA has been shown to aggregate significantly within families, suggesting an inherited basis for this disorder.9–11 The probability of developing OSA appears to increase progressively with increasing numbers of affected family members. While individuals with one affected family member have an estimated 30–58% increased risk for developing OSA, those with three affected family members have an estimated 2–4-fold increased risk.12 Overall, approximately 30–40% of the variability in apneic activity in the population can be explained by variability in familial factors.9 A report of increased prevalence of HLA-A2 in Japanese patients with OSA supports the concept of an inherited defect.13 This increased incidence of OSA in families is not completely explained by familial similarities in body mass index or neck circumference, and persists despite adjustments for other well-known risk factors such as age and male sex.12,13 It has been postulated that inherited craniofacial abnormalities such as a high and narrow hard palate, shorter mandibles, retroposed maxillae and mandibles, longer soft palates and wider uvulae are important in
4
Obstructive sleep apnea: the syndrome Jaw malformation Jaw Malformation
Nasal obstruction
Enlarged tongue
Obesity
Nasal cavities
Floppy epiglottis
Enlarged tonsils and adenoids
Paralysedvocal vocal cord cord Paraivsed
Enlarged soft palate Upper airway tumor Hypopharynx
Velopharynx
Laryngopharynx Gropharynx
Nasopharynx
the pathogenesis of OSA.10,14 However, differences in craniofacial morphology between patients with sleep apnea and control relatives without sleep apnea were small, implying that other factors may be important in familial OSA.9,10,12 Recent studies have noted that family members of subjects with OSA demonstrate blunting of the hypoxic ventilatory response, a greater increase in impedance during inspiratory loading, and a reduced ability to compensate for increased inspiratory loads.12,15 These findings suggest that a genetic susceptibility to OSA may be related to abnormalities in ventilatory control mechanisms and the regulation of upper airway patency.
Pathogenesis and risk factors It is well recognized that narrowing of the human pharynx or upper airway is responsible
Figure 1.1 Diagram of the upper airway showing the different segments of the pharynx and indicating the variety of upper airway abnormalities reported to cause obstructive sleep apnea. (Adapted from Fleetham JA. Upper airway imaging in relation to obstructive sleep apnea. Clin Chest Med 1992;13:400.)
for all the consequences associated with obstructive sleep apnea.16 The pharynx is typically divided into three segments, the nasopharynx (end of the nasal septum to the margin of the soft palate), the oropharynx (free margin of the soft palate to the tip of the epiglottis), which is divided into the retropalatal and retroglossal regions, and the hypopharynx (tip of the epiglottis to the vocal cords) (Figure 1.1). In one study, 75% of patients had more than one site of narrowing, the retropalatal region or velopharynx being the most common site.17 Since a decrease in size or narrowing of the human upper airway or pharynx is the underlying cause of OSA, individuals with this condition must have some abnormality or abnormalities leading to narrowing of their upper airway. According to the ‘balance of pressures’ concept proposed by Remmers et al, there are five major determinants of the size or caliber of the upper airway (Figure 1.2): (1) the baseline pharyngeal area, which is determined by both craniofacial and soft tissue
Pathogenesis and risk factors
Pmusc
Ptis
PL
PL
Ptis
Compliance =
Pmusc
6V 6P
Figure 1.2 Determinants of upper airway caliber. PL = intraluminal pressure; Ptis = pressure in the tissues surrounding the pharyngeal wall; Pmusc = pressure exerted by the pharyngeal dilating muscles; 6V = change in volume; 6P = change in pressure.
structures (Figure 1.1); (2) the compliance or collapsibility of the airway; (3) the pressure within the airway (intraluminal pressure, PL), which on inspiration is negative, due to the upwardly transmitted negative intrapleural pressure, and tends to narrow the airway; (4) the pressure acting on the outside surface of the pharyngeal wall (tissue pressure, Ptis), which can be positive, and also tends to collapse the airway—examples include compression by the lateral pharyngeal fat pad, a large neck, the effect of gravity on submandibular fat, and a large tongue confined to a small oral cavity; and (5) the pressure exerted by the pharyngeal dilating
5
muscles (Pmusc), which is directed outwards, and functions to increase cross-sectional area and decrease pharyngeal compliance.17–19 In addition, there is theoretical evidence that the shape of the upper airway is also important. Compared to the wide, elliptically shaped airway of normal controls, the long axis of which is oriented transversely, the pharynx of patients with OSA is narrow and has its long axis in the anteroposterior direction. Such an orientation could decrease Pmusc by diminishing the mechanical effectiveness of upper airway muscle contraction.20,21 Finally, lung volume independently influences upper airway caliber, resistance and compliance. Decreased lung volume results in a decrease in the area of the pharynx, an increase in its compliance or collapsibility, and the loss of caudal traction or tug on the trachea.22–25 The consequence of the loss of tracheal tug is an increase in upper airway resistance.22 Although narrowing of the human upper airway is the primary event in OSA, the occurrence of oxyhemoglobin desaturation during the abnormal respiratory event is dependent on several other factors. The primary determinants of oxyhemoglobin desaturation with OSA include: (1) the length of the abnormal respiratory event—the longer the event, the more likely it is that oxyhemoglobin desaturation will occur; (2) the type of respiratory event, obstructive events being associated with respiratory effort and therefore greater oxygen consumption than central events with absent respiratory effort; (3) the quantity of oxygen stored in the lungs, which is proportional to the lung volume and the fractional concentration of oxygen in the alveoli (a small lung volume is associated with greater desaturation than a large lung volume); (4) the mixed venous oxygen saturation, the lower this saturation— the more rapid the rate of fall in arterial oxyhemoglobin saturation; (5) the body mass index
6
Obstructive sleep apnea: the syndrome
% Saturation of hemoglobin
100
6SaO2 6SaO2
50
0
0
30
60 PaO2 (mmHg)
90
Figure 1.3 Effect of initial arterial oxygen tension (PaO2) and saturation (SaO2) on extent of arterial oxygen desaturation seen with an apnea or hypopnea. Because of the shape of the oxygen–hemoglobin dissociation curve, the amount of decrease in SaO2 and corresponding PaO2 is different for different starting PaO2s. When the starting PaO2 is near or below the ‘elbow’ of the curve, more oxygen desaturation is seen with a given apnea or hypopnea compared to a starting PaO2 on the ‘plateau’ of the curve.
(BMI) of the subject—obese subjects consume more oxygen per minute than slender subjects; and (6) the baseline arterial oxygen saturation—the lower the value, the closer you are to the knee of the oxyhemoglobin dissociation curve at the start of the abnormal respiratory event, and the more likely you are to desaturate (Figure 1.3).17 Although numerous changes occur during sleep, those most important in the pathogenesis of OSA are the decrease in both Pmusc and lung volume associated with sleep onset.26–28 The latter exacerbates the decreased lung
volume associated with assumption of the supine position. In addition, the effect of gravity on a large neck or parapharyngeal fat may increase Ptis. The overall result is an increase in upper airway resistance due to the decrease in cross-sectional area and increase in compliance or collapsibility of the upper airway.28,29 Stiffer, smaller lungs and resultant atelectasis may also cause a decrease in baseline oxyhemoglobin saturation and the other determinants of the degree of oxyhemoglobin desaturation with an apnea, hypopnea or hypoventilation. The pharynx of persons without OSA has sufficient ‘reserve’ to tolerate this increase in upper airway resistance and collapsibility associated with sleep. In contrast, individuals with OSA have some predisposing condition, either a pharynx with a baseline area that is too small, or an abnormality in one or more of the determinants of upper airway caliber mentioned above. Thus when they fall asleep, their upper airway cannot tolerate this decrease in Pmusc and lung volume and increase in Ptis. The result is an upper airway that narrows enough to have physiologic consequences (see below). Those factors that have been shown to predispose to OSA, and how they interact with the determinants of upper airway caliber described above, are shown in Table 1.1. See also Figure 1.1 for examples of upper airway anatomic abnormalities that can predispose to OSA. Since REM sleep is associated with greater muscle hypotonia compared to non-REM sleep, sleep-disordered breathing is more likely to occur during REM sleep.30 In addition, the more impaired ventilatory responses to hypoxia and hypercapnia contribute to the longer duration of abnormal respiratory events and the presence of post-apneic hypoventilation during REM sleep.31,32 The
Pathogenesis and risk factors
7
Table 1.1 Factors predisposing to the obstructive sleep apnea syndrome and how they interact with the determinants of pharyngeal caliber. Predisposing factor
Awake pharyngeal area
Luminal pressure (PL)
Tissue pressure (Ptis)
Pharyngeal muscle dilating force (Pmusc)
Pharyngeal compliance
Obesity Neuromuscular disease Alcohol Sedative hypnotics Nasal congestion Abnormal anatomy Supine position Sleep deprivation Hypothyroidism Acromegaly
Decreased Decreased Decreased – – Decreased Decreased – Decreased Decreased
– – – – Increased – – – – –
Increased ? – – – – – Increased – Increased Increased
Decreased ? Decreased Decreased Decreased – – – Decreased Decreased –
Increased Increased – – – – – Increased – –
(Adapted from Koenig SM, Suratt PM. Obesity and sleep-disordered breathing. In: Alpert MA, Alexander JD, eds. The Heart and Lung in Obesity. Armong, New York: Futura Publishing Company, 1998:156.)
result is more frequent and more severe episodes of increased upper airway resistance and oxyhemoglobin desaturation compared to non-REM sleep. To predispose to OSA, obesity must influence one or more of the above-mentioned determinants of upper airway caliber, or of degree of oxyhemoglobin desaturation associated with a given abnormal respiratory event. As it turns out, there is evidence that obesity can affect all of these determinants, which explains not only why obesity is the most common factor predisposing to OSA, but why obese individuals with OSA are more likely to have more severe clinical consequences than their non-obese counterparts (Figure 1.4). Although it is unclear whether the predominant mechanism is increased Ptis or simply excessive parapharyngeal tissue without an
increase in Ptis, the majority of studies indicate that, compared to weight-matched controls, obese patients with OSA have a smaller baseline upper airway cross-sectional area. This narrowing is located predominantly in the retropalatal region.19,33 Logic would dictate that excessive adipose tissue should be the cause of this decreased area, and there is evidence to support this hypothesis. Using magnetic resonance imaging (MRI), which can distinguish soft tissue from fat, one study indicated that, compared to weight-matched controls, obese patients with OSA had excess fat deposition in the soft palate, tongue and areas posterior and lateral to the oropharynx at the level of the palate.34 Two other MRI studies confirmed the smaller baseline pharyngeal area in obese subjects with OSA, and also demonstrated the presence of a larger volume
8
Obstructive sleep apnea: the syndrome
OBESITY
Parapharyngeal fat
Thickness, lateral parapharyngeal walls
Abdominal, chest wall, diaphragm fat
Lung volume
Tracheal tug
Baseline UA area
UA compliance
Pmusc
A-P orientation of UA
UA caliber
UAR
Ptis
+
Respiratory load compensation
OSA
Figure 1.4 The pathophysiologic role of obesity in the obstructive sleep apnea syndrome. UA, upper airway; UAR, upper airway resistance; OSA, obstructive sleep apnea; A-P, anterior–posterior; Ptis = pressure in tissues surrounding the pharyngeal wall; Pmusc = pressure exerted by pharyngeal dilating muscles. (Adapted from Koenig SM, Suratt PM. Obesity and sleepdisordered breathing. In: Alpert MA, Alexander JD, eds. The Heart and Lung in Obesity. Armong, New York: Futura Publishing Company, 1998:157.)
of adipose tissue adjacent to the pharyngeal airway.35,36 Moreover, not only did the volume of this parapharyngeal fat correlate with the degree of OSA, but weight loss resulted in a substantial decrease in both pharyngeal adipose tissue volume and the severity of OSA.36 In addition, surgical specimens from
individuals with OSA who underwent uvulopalatopharyngoplasty (UPPP) (see below) have demonstrated increased fat in the soft palate.37 In contrast, although Schwab et al confirmed that airway size is smaller in patients with sleep apnea, their findings
Pathogenesis and risk factors indicated that it was the thickness of the lateral pharyngeal wall and not the size of the soft palate, tongue or parapharyngeal fat pads that was the major anatomic factor causing airway narrowing in apneics.38 Moreover, using a proton spectroscopic technique called hydrogen ultrathin phase-encoded spectroscopy (HUPSPEC) with MRI, he demonstrated that this increased thickness of the lateral pharyngeal walls was not secondary to increased fat infiltration or edema.39,40 He went on to hypothesize that obesity may predispose to sleep apnea by increasing the size of the upper airway soft tissue structures themselves (tongue, soft palate, lateral pharyngeal walls), rather than by the direct deposition of fat in the parapharyngeal fat pads or by compressing the lateral walls by these fat pads. Thus, although most evidence supports a smaller baseline upper airway caliber in obese patients, the exact mechanism of this narrowing remains to be defined. Fat might also encroach on the upper airway lumen and alter its shape without necessarily reducing its diameter. With MRI, differences in pharyngeal shape but not in cross-sectional area have been documented between obese patients and normal-weight controls.21 When the pharynx was viewed in coronal section, the airways of normal awake controls were in the shape of an ellipse, with the long axis oriented transversely. In contrast, awake OSA patients had elliptically shaped airways oriented in an anteroposterior or longitudinal direction. Non-apneic snorers had upper airway shapes intermediate between these two groups. Using CT scanning, Schwab et al made similar findings.19 These results are consistent with reports that the upper airway collapses laterally during sleep when viewed endoscopically or by fast CT.36 Whether the longitudinal orientation of the pharynx in patients with OSA is secondary to
9
lateral encroachment by fat, i.e. an increase in Ptis, or to pharyngeal dilator muscles pulling the airway anteriorly, is unknown. However, as mentioned above, this anteroposterior orientation could diminish the ability of pharyngeal muscles to dilate the upper airway (i.e. decreased Pmusc).20 Several measures have been used to evaluate the compliance or collapsibility of the human upper airway, including acoustic reflection techniques that measure the lung volumerelated change in pharyngeal area, nasopharyngeal resistance and the critical closing pressure of the airway or Pcrit. Pcrit is the luminal pressure at which the cross-sectional area of the upper airway becomes zero. Regardless of the technique employed, numerous studies have suggested that fat surrounding the human upper airway increases the compliance of the pharynx.23–25,41–43 This increased compliance or collapsibility could result from a direct effect on the airway itself or an indirect effect on the function of the upper airway dilator muscles (i.e. decreased Pmusc). Obesity, particularly central or upper body obesity, can also result in decreased lung volume.44,45 Since pharyngeal area and resistance are directly proportional, and compliance is inversely proportional to lung volume, obesity can decrease the baseline area and increase the resistance and compliance of the upper airway simply by its effect on lung volume.22–25 Obesity can also affect the degree of oxyhemoglobin desaturation and hypercapnia associated with a given abnormal respiratory event by several mechanisms: (1) increased baseline oxygen consumption and carbon dioxide production; and (2) decreased lung volume, which increases mismatch of ventilation and perfusion from airway closure and collapse (atelectasis); this results in decreased oxygen stores in the lung, decreased mixed venous oxygen saturation and a lower baseline
10
Obstructive sleep apnea: the syndrome
oxyhemoglobin saturation.46–48 Thus, for a given abnormal respiratory event, an obese individual is more likely than his non-obese counterpart to have oxyhemoglobin desaturation and hypercapnia. Neck circumference is a simple clinical measurement that reflects obesity in the region of the upper airway. Studies have indicated that patients with OSA have larger necks than nonapneic snorers as well as weight-matched controls.49,50 This parameter is related to obesity, apnea severity, tongue and soft palate size, as well as maxillary, mandibular and hyoid bone position, all thought to be important in the pathogenesis of OSA.33,51–56 In addition, of all the anthropometric measurements, including BMI, the neck circumference, particularly if adjusted for height, was the strongest predictor of sleep-disordered breathing.49,57 Hip-to-waist ratio, another measure of central obesity, also exhibits a better correlation with OSA severity than BMI.58 These findings suggest that it is the distribution of fat, in particular upper body obesity, rather than total body fat, that is important to the development of OSA. In one study, only neck circumference and retroglossal space were independent correlates of apnea severity.59 Nonetheless, although a more useful predictor of OSA than BMI and other signs and symptoms, neck circumference alone, even if corrected for height, is neither sufficiently sensitive nor sufficiently specific to avoid the need for further diagnostic testing to establish the diagnosis (r2 = 0.38; sensitivity = 87%; specificity = 79%; positive predictive value = 66%).57
Clinical features Sleep-disordered breathing has two primary outcomes, arousal from sleep and oxyhemoglobin desaturation and hypercapnia. The
Table 1.2 Consequences of arousal from sleep. Sleep fragmentation Excessive daytime sleepiness Personality changes Intellectual deterioration Visual–motor incoordination Impotence Insomnia Restlessness Choking, gagging, gasping, resuscitative snorting
Table 1.3 Consequences of nocturnal hypoxia/hypercapnia. Polycythemia Pulmonary hypertension Cor pulmonale Chronic hypercapnia Morning and nocturnal headache Left-sided congestive heart failure Cardiac dysrhythmias Nocturnal angina Diurnal systemic hypertension
consequences of these abnormalities are depicted in Tables 1.2 and 1.3. Although daytime sleepiness, fatigue, irritability and personality change have been attributed to both nocturnal oxyhemoglobin desaturation and the chronic sleep deprivation caused by sleep fragmentation, arousal from sleep is considered the more important of the two factors.60 Daytime sleepiness and visual–motor incoordination are the presumed cause of the increased rate of automobile (seven-fold) and work-related accidents in patients with OSA
Clinical features compared to the general population.61,62 The most common cardiac dysrhythmia observed in patients with OSA is a cyclic decrease and then increase in heart rate (sinus bradytachyarrhythmia).63,64 Other associated bradydysrhythmias include marked sinus bradycardia (< 30 beats/min), sinus arrest (> 2.5 s) and second-degree atrioventricular (A-V) block. Supraventricular paroxysmal depolarizations (SVPDs), ventricular paroxysmal depolarizations (VPDs), atrial fibrillation, atrial flutter and ventricular tachycardia are also reported. Unless there is coexistent coronary artery disease, increased VPDs and ventricular tachycardia do not typically occur until oxyhemoglobin saturation drops to less than 60–65%.65,66 Patients with sleep-disordered breathing may present with all, or only a few, of the symptoms and signs listed in Tables 1.2 and 1.3. Whether an individual presents with snoring, symptoms of sleep fragmentation, signs of hypoxia/hypercapnia or a combination of these, depends on several factors (Figure 1.5). As has already been mentioned, everything begins with some predisposing abnormality or abnormalities of the upper airway. When this predisposing factor(s) is combined with the decreased pharyngeal dilator muscle activity and lung volume and increased Ptis that accompanies sleep onset, some degree of upper airway narrowing occurs. If the soft portions of the oropharynx and nasopharynx vibrate, snoring will also result. For snoring to occur, you need both the proper structure, e.g. a long floppy uvula and soft palate, as well as exposure to an inspiratory pressure negative enough to set these tissues in motion. The reason why more than 80% of individuals with OSA snore is that the most common site of upper airway abnormality and narrowing is the region around the soft palate.
11
Predisposing factor + Sleep onset
Snoring
Decreased pharyngeal muscle activity and lung volume
Pharyngeal narrowing
Obstructive apnea/hypopnea
Hypoxia and hypercapnia
Inadequate respiratory load compensation Increased ventilatory effort Adequate respiratory load compensation Arousal from sleep
Figure 1.5 Pathophysiology of obstructive sleep apnea. (Adapted from Koenig SM, Suratt PM. Obesity and sleep-disordered breathing. In: Alpert MA, Alexander JD, eds. The Heart and Lung in Obesity. Armong, New York: Futura Publishing Company, 1998:165.)
Depending on the degree of narrowing and resultant increase in upper airway resistance, ventilatory effort may increase to maintain the required ventilation. Because increased ventilatory effort is transmitted to the upper airway in the form of a greater negative intraluminal pressure (PL), the pharynx will become narrower, further increasing upper airway resistance, and a vicious cycle may ensue.
12
Obstructive sleep apnea: the syndrome
Studies have demonstrated that the arousal from sleep that opens the upper airway and terminates an abnormal respiratory event during sleep is much more tightly linked to the tension–time index of the diaphragm than oxyhemoglobin desaturation.67,68 The tension–time index of the diaphragm is an indicator of ventilatory effort. If this ‘ventilatory effort arousal threshold’ is exceeded while the respiratory muscles are still able to compensate for the increased upper airway resistance or load, an arousal from sleep alone, without a decrease in airflow, i.e. without an apnea or hypopnea (see below), will occur. And, without diminished airflow, no oxyhemoglobin desaturation or hypercapnia will result. This condition, which is associated with daytime fatigue, tiredness and sleepiness due to the sleep fragmentation induced by the arousals, has been termed the upper airway resistance syndrome (UARS).69 (see below). Interestingly, several patients with UARS, all women, did not even snore. If ventilatory effort does not exceed its ‘arousal threshold’ prior to the respiratory muscles becoming unable to compensate for the increased upper airway resistance or load, a decrease in airflow and tidal volume occurs; this is called a hypopnea. If airflow ceases completely prior to arousal from sleep, an apnea occurs. An apnea is defined as the complete or near complete cessation of airflow that lasts for at least 10 s.70 A hypopnea is defined as a * 50% decrease in airflow or a < 50% decrease lasting at least 10 s with either an oxyhemoglobin desaturation of * 3% or an arousal from sleep.70 Both abnormal breathing events are associated with similar sequelae, are treated in the same manner, and often occur together in the same patient. There are two possible outcomes of a hypopnea and apnea: a further increase in ventilatory effort followed by an arousal
alone, or hypoxia and hypercapnia, which independently, as well as by further increasing ventilatory effort, usually result in an arousal from sleep. The determinants of whether an apnea or hypopnea result in oxyhemoglobin desaturation and hypercapnia, as well as the severity of these abnormalities if they do occur, are discussed above. Finally, if both the ‘ventilatory effort arousal threshold’ and an individual’s ability to compensate for hypoxia, hypercapnia and respiratory loads are sufficiently blunted, hypoventilation alone, without the periodic arousals that terminate hypopneas, apneas or increased UAR, results. Thus the term OSA is not, strictly speaking, applicable to the entire spectrum of sleep-disordered breathing, but is best reserved for those individuals with the most severe form of the disease. The term obstructive sleep-disordered breathing syndrome (OSDB) better describes the entire spectrum of obstructive breathing abnormalities during sleep (Figure 1.6). At one end of the upper airway resistance continuum there is primary, asymptomatic snoring. This is followed by the UARS, then by the sleep hypopnea syndrome, and finally by the sleep apnea syndrome. The obesity hypoventilation syndrome is used to describe individuals with OSDB who also have daytime hypoventilation and who are typically morbidly obese. The major factors that determine where along the spectrum of OSDB a patient lies are the ‘ventilatory effort arousal threshold’ and the resistive load compensation. Whether hypoventilation, a hypopnea or an apnea eventuates in hypoxia and hypercapnia depends on the individual’s underlying pulmonary function and the duration of the abnormal respiratory event, the latter determined primarily by the ‘ventilatory effort arousal threshold.’ Regarding some of the other long-term consequences of OSDB, several retrospective
Clinical diagnosis Upper airway resistance '
0 Snoring
Arousal
Hypopnea
Apnea
UA vibration
Yes
Yes/No
Yes/No
Yes/No
Ventilatory effort arousal threshold exceeded
No
Yes
No
No
Adequate respiratory load compensation
Yes
Yes
No
No
Clinical syndrome
Primary snoring
UARS
Sleep hypopnea syndrome
Sleep apnea syndrome
Figure 1.6 Spectrum of obstructive sleep-disordered breathing syndrome. UA, upper airway; UARS, upper airway resistance syndrome. The degree of resultant hypoxia and hypercapnia depends on the patient’s underlying cardiopulmonary function (i.e. arterial and mixed venous oxyhemoglobin saturation, lung volumes) and the duration of the abnormal respiratory event. If daytime hypercapnia is present and the patient morbidly obese, the term obesity hypoventilation syndrome is used. (Adapted from Koenig SM, Suratt PM. Obesity and sleep-disordered breathing. In: Alpert MA, Alexander JD, eds. The Heart and Lung in Obesity. Armong, New York: Futura Publishing Company, 1998:167.)
studies have shown that both the OSA syndrome and snoring were associated with an increased prevalence of hypertension, coronary artery disease and cerebral vascular accidents, even when adjustments were made for other risk factors such as weight, age,
13
smoking and sex.71–73 That snoring alone is associated with increased cardiovascular morbidity suggests that even mild degrees of sleep-disordered breathing may have adverse health effects. Finally, in yet another retrospective study, He et al. demonstrated that untreated significant OSA, defined as an apnea index (AI) > 20, was associated with excess mortality.74 Because current morbidity and mortality data are based on retrospective studies, the true impact of sleep-disordered breathing on society remains unknown. A randomized trial is clearly required, and, in fact, is presently ongoing. The mechanism whereby sleep-disordered breathing increases the risk of cardiovascular disease and consequences is unclear. It appears to be mediated by a complex interaction between the mechanical effects of repetitive increased upper airway resistance, the oftenassociated hypoxia and hypercapnia, and their effect on the autonomic nervous system as well as increased platelet aggregation that has been described in untreated sleep apnea.7,75–77
Clinical diagnosis The possibility of sleep-disordered breathing should be considered in any patient with any of the predisposing factors, signs or symptoms mentioned above (Tables 1.1–1.3). Talking with the bed partner, family members, friends or fellow employees can be very helpful, as they will often notice signs, such as apneas or falling asleep unintentionally, that the patient may be unaware of or deny. The next step is to estimate a clinical likelihood or pretest probability of sleep-disordered breathing based on a focused history and physical examination. This evaluation should include searching for alternative explanations for symptoms, such
14
Obstructive sleep apnea: the syndrome
Table 1.4 Features most useful in determining the probability of obstructive sleep-disordered breathing. Male sex Age > 40 Habitual snoring Nocturnal gasping, choking or resuscitative snorting Witnessed apnea BMI > 25 kg/m2, or neck circumference ⭓ 17 inches in males, ⭓ 16 inches in females Systemic hypertension BMI, body mass index.
as insufficient sleep or shiftwork causing excessive daytime sleepiness. Those symptoms and signs that have been shown to be most useful in determining the need for further diagnostic evaluation are listed in Table 1.4. Symptoms of excessive daytime sleepiness, unrefreshing or non-restorative sleep, morning headaches, cognitive impairment, depression, nocturnal esophageal reflux (due to increases in abdominal pressure during upper airway obstruction), nocturia or enuresis (due to increased intra-abdominal pressure and/or secretion of atrial natriuretic hormone), hearing loss, automatic behavior, sleep drunkenness (disorientation, confusion upon awakening), hypnagogic hallucinations and night sweats, although commonly reported, do not distinguish sleep apnea from other nonpulmonary sleep disorders. In any patient presenting with a complaint of daytime sleepiness, the degree of sleepiness should be quantitated. The sleepier the individual, the more likely it is that he has sleep-disordered breathing or some other significant disorder, and the more severe the
Table 1.5 Sleep-inducing situations in sleep apnea patients. Situation
% of patients
Watching television Reading Riding in a car (passenger) Church Visiting friends or relatives Driving in a car Working Waiting at a traffic light
91 85 71 57 54 50 43 32
n = 385 patients. (Adapted from Roth T, Roehrs TA, Carskadon MA, Dement WC. Daytime sleepiness and alertness. In: Kryger MH, Roth T, Dement WC, eds. Principles and Practice of Sleep Medicine. Philadelphia: WB Saunders Company, 1994:43.)
condition; the severity or the condition influences treatment (see below). A reasonable approach is to divide sleepiness into mild, moderate and severe, based on the frequency of sleep episodes, the degree of impairment of social and occupational function, and the situations in which sleep episodes occur.78 With mild sleepiness, sleep episodes are infrequent, may not occur every day, and occur at times of rest or when little attention is required, such as while watching TV, reading, or traveling as a passenger. Sleepiness is considered severe when it is present daily and when sleep episodes occur even during activities requiring sustained attention, such as eating, conversation, walking and driving. Moderate sleepiness lies somewhere in between these extremes. Table 1.5 presents those sleep-inducing situations most commonly reported by patients with OSA syndrome.
Clinical diagnosis It is important to remember that although the majority of patients with sleep-disordered breathing are sleepy when measured by multiple sleep latency testing (MSLT), daytime sleepiness is underreported.79,80 MSLT is an objective measure of sleepiness (see below). Fatigue may be the only symptom reported. This situation probably results because sleepdisordered breathing develops over a long period, and patients adapt their lifestyles to compensate for it. In addition, sleepiness may be denied because of lack of awareness of risk, embarrassment, or concern regarding punitive actions such as loss of occupation.81 Thus the absence of sleepiness cannot be used to reliably exclude OSA. In addition, sleep-disordered breathing is not the only cause of excessive daytime sleepiness (EDS) (Chapter 2). That is, EDS is not specific for sleep-disordered breathing either. Those physical examination findings that significantly increase the likelihood of sleepdisordered breathing are listed in Table 1.4. Other features that should be searched for include craniofacial and upper airway abnormalities such as retrognathia; tonsillar hypertrophy, especially in children; and an enlarged soft palate. The size and consistency of the tongue, presence of pharyngeal edema or abnormal reddish coloring of the pharynx, appearance of the soft palate, size, length and position of the uvula, evidence of trauma, and nares, including whether they collapse with inspiration, particularly while the patient is supine, should also be noted (Figure 1.1). Unfortunately, subjective impression alone, based on history and physical examination, lacks both sensitivity (52–78%) and specificity (50–79%).82–85 Although plugging clinical variables into regression formulas improves these operating characteristics somewhat (sensitivity 79–92%, specificity 50–51%), many involve complicated mathematical formulas,
15
which limits their usefulness.83,85,86 Moreover, even if the clinical likelihood is low, the posttest probability for OSA, defined as a respiratory disturbance index (RDI) > 10, still varies between 16% and 21%.83,86,87 In addition, since the criterion for the diagnosis of OSA in these studies was an RDI > 10–15, patients with symptoms secondary to UARS would have been missed, decreasing the sensitivity of clinical assessment even further. Whether a post-test probability for OSA of 16–21% is low enough will depend on the threshold at which a physician is willing to accept diagnostic uncertainty. The threshold for pursuing further diagnostic testing will probably be lower in patients with severe daytime sleepiness, comorbid illnesses such as coronary artery disease, a driving accident record and certain occupations, i.e. school bus driver. Recently, a morphometric model that combines measurements of the oral cavity with BMI and neck circumference has been recommended as a screening tool for OSA syndrome.88 This model had a sensitivity of 97.6%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 88.5%. Although these results are quite impressive, verification of this morphometric model by other investigators and in other sleep clinic populations must be performed before it can be recommended. The diagnosis of sleep-disordered breathing should also be considered in any individual with unexplained daytime hypercapnia, polycythemia, pulmonary hypertension or cor pulmonale. Patients with hypercapnia and pulmonary hypertension secondary to chronic obstructive pulmonary disease (COPD) typically have a forced expiratory volume in 1 second (FEV1 < 1–1.3 l/min (30% of predicted).89 Pulmonary hypertension predictably occurs in COPD when arterial oxygen tension PaO2 is < 50 mmHg and PaCO2 is
16
Obstructive sleep apnea: the syndrome
> 45 mmHg.90,91 Those with pulmonary hypertension due to restrictive lung disease usually have a forced vital capacity (FVC) < 50% of predicted.92 With systemic sclerosis, a diffusing capacity for carbon monoxide < 43% was a better predictor of pulmonary hypertension than a FVC < 50%, having a sensitivity of 67%.93
References 1. Young T, Palta M, Dempsey J, Skatrud J, Weber S, Badr S. The occurrence of sleepdisordered breathing among middle-aged adults. N Engl J Med 1993;328:1230–5. 2. Ancoli-Israel S. Epidemiology of sleep disorders. Clin Geriatr Med 1989;5:347–62. 3. Gislason T, Almqvist M, Eriksson G, Taube A, Boman G. Prevalence of sleep apnea syndrome among Swedish men—an epidemiological study. J Clin Epidemiol 1988;41:571–6. 4. Lauie P. Incidence of sleep apnea in a presumably healthy working population: a significant relationship with excessive daytime sleepiness. Sleep 1983;6:312–18. 5. Peter JH, Fuchs E, Kohler U et al. Studies in the prevalence of sleep apnea activity (SAA): evaluation of ambulatory screening results. Eur J Respir Dis – Suppl 1986;146:451–8. 6. Stoohs RA, Bingham LA, Itoi A, Guilleminault C, Dement WC. Sleep and sleep-disordered breathing in commercial long-haul truck drivers. Chest 1995;107:1275–82. 7. Bonsignore MR, Marrone O, Insalaco G, Bonsignore G. The cardiovascular effects of obstructive sleep apnoeas: analysis of pathogenic mechanisms. Eur Respir J 1994;7:786–805. 8. National Commission on Sleep Disorders Research. Wake up America: A National Sleep Alert. Washington, DC: Government Printing Office, 1993.
9. Mathur R, Douglas NJ. Family studies in patients with the sleep apnea–hypopnea syndrome. Ann Intern Med 1995;122:174–8. 10. Redline S, Tishler PV, Tosteson TD et al. The familial aggregation of obstructive sleep apnea. Am J Respir Crit Care Med 1995;151:682–7. 11. Pillar G, Lavie P. Assessment of the role of inheritance in sleep apnea syndrome. Am J Respir Crit Care Med 1995;151:688–91. 12. Redline S, Leitner J, Arnold J, Tishler PV, Altose MD. Ventilatory-control abnormalities in familial sleep apnea. Am J Respir Crit Care Med 1997;156:155–60. 13. Redline S, Tosteson T, Tishler PV, Carskadon MA, Millman RP. Studies in the genetics of obstructive sleep apnea. Familial aggregation of symptoms associated with sleep-related breathing disturbances [published erratum appears in Am Rev Respir Dis 1992;145(4 Pt 1):979]. Am Rev Respir Dis 1992;145:440–4. 14. Guilleminault C, Partinen M, Hollman K, Powell N, Stoohs R. Familial aggregates in obstructive sleep apnea syndrome. Chest 1995;107:1545–51. 15. Pillar G, Schnall RP, Peled N, Oliven A, Lavie P. Impaired respiratory response to resistive loading during sleep in healthy offspring of patients with obstructive sleep apnea. Am J Respir Crit Care Med 1997;155:1602–8. 16. Burwell CS, Robin ED, Whaley R, Bickelmann AG. Extreme obesity associated with alveolar hypoventilation. A Pickwickian syndrome. Am J Med 1956;21:811. 17. Powell NB, Guilleminault C, Riley RW. Principles and Practice of Sleep Medicine. Philadelphia: WB Saunders Company, 1994:706–21. 18. Remmers JE, deGroot WJ, Sauerland EK, Anch AM. Pathogenesis of upper airway occlusion during sleep. J Appl Physiol 1978;44:931–8. 19. Schwab RJ, Gefter WB, Hoffman EA, Gupta KB, Pack AI. Dynamic upper airway imaging during awake respiration in normal subjects and patients with sleep-disordered breathing. Am Rev Respir Dis 1993;148:1385–400.
References 20. Leiter JC. Upper airway shape: is it important in the pathogenesis of obstructive sleep apnea? Am J Respir Crit Care Med 1996;153:894–8. 21. Rodenstein DO, Dooms G, Thomas Y et al. Pharyngeal shape and dimensions in healthy subjects, snorers, and patients with obstructive sleep apnoea. Thorax 1990;45:722–7. 22. Van de Graaff WB. Thoracic traction on the trachea: mechanisms and magnitude. J Appl Physiol 1991;70:1328–36. 23. Brown IG, Bradley TD, Phillipson EA, Zamel N, Hoffstein V. Pharyngeal compliance in snoring subjects with and without obstructive sleep apnea. Am Rev Respir Dis 1985;132:211–15. 24. Hoffstein V, Zamel N, Phillipson EA. Lung volume dependence of pharyngeal crosssectional area in patients with obstructive sleep apnea. Am Rev Respir Dis 1984;130:175–8. 25. Brown IB, McClean PA, Boucher R, Zamel N, Hoffstein V. Changes in pharyngeal crosssectional area with posture and application of continuous positive airway pressure in patients with obstructive sleep apnea. Am Rev Respir Dis 1987;136:628–32. 26. Berger RJ. Tonus of extrinsic laryngeal muscles during sleep and dreaming. Science 1961;134:840 27. Ballard RD, Irvin CG, Martin RJ. Influence of sleep on lung volume in asthmatic patients and normal subjects. J Appl Physiol 1990;68:2034–41. 28. Wiegand DA, Latz B, Zwillich CW et al. Geniohyoid muscle activity in normal men during wakefulness and sleep. J Appl Physiol 1990;69:1262–9. 29. Hudgel DW, Martin RJ, Johnson B et al. Mechanics of respiratory system and breathing pattern during sleep in normal humans. J Appl Physiol 1984;56:133–7. 30. Orem J. Medullary respiratory neuron activity: relationship to tonic and phasic REM sleep. J Appl Physiol 1980;48:54–65.
17
31. Berthon-Jones M, Sullivan CE. Ventilation and arousal responses to hypoxia in sleeping humans. Am Rev Respir Dis 1982;125:632–9. 32. Douglas NJ, White DP, Weil JV, Pickett CK, Zwillich CW. Hypercapnic ventilatory response in sleeping adults. Am Rev Respir Dis 1982;126:758–62. 33. Rivlin J, Hoffstein V, Kalbfleisch J, McNicholas W, Zamel N, Bryan AC. Upper airway morphology in patients with idiopathic obstructive sleep apnea. Am Rev Respir Dis 1984;129:355–60. 34. Horner RL, Mohiaddin RH, Lowell DG et al. Sites and sizes of fat deposits around the pharynx in obese patients with obstructive sleep apnoea and weight matched controls. Eur Respir J 1989;2:613–22. 35. Shelton KE, Gay SB, Hollowell DE, Woodson H, Suratt PM. Mandible enclosure of upper airway and weight in obstructive sleep apnea. Am Rev Respir Dis 1993;148:195–200. 36. Shelton KE, Woodson H, Gay S, Suratt PM. Pharyngeal fat in obstructive sleep apnea. Am Rev Respir Dis 1993;148:462–6. 37. Stauffer JL, Buick MK, Bixler EO et al. Morphology of the uvula in obstructive sleep apnea. Am Rev Respir Dis 1989;140:724–8. 38. Schwab RJ, Gupta KB, Gefter WB, Metzger LJ, Hoffman EA, Pack AI. Upper airway and soft tissue anatomy in normal subjects and patients with sleep-disordered breathing. Significance of the lateral pharyngeal walls. Am J Respir Crit Care Med 1995;152: 1673–89. 39. Listerud J, Lenkinski RE, Axel L, Roberts M. Hydrogen ultrathin phase-encoded spectroscopy (HUPSPEC). Magnet Reson Imag 1990;14:507–21. 40. Schwab RJ, Prasad A, Gupta KB et al. Fat and water measurements of the upper airway soft tissues in normal subjects and patients with sleep-disordered breathing using magnetic resonance proton spectroscopy. Am Rev Respir Dis 1991;145:A214 (abstract). 41. Bradley TD, Brown IG, Grossman RF et al.
18
42.
43.
44.
45.
46.
47.
48.
49.
50.
51.
Obstructive sleep apnea: the syndrome Pharyngeal size in snorers, nonsnorers, and patients with obstructive sleep apnea. N Engl J Med 1986;315:1327–31. Rubinstein I, Colapinto N, Rotstein LE, Brown IG, Hoffstein V. Improvement in upper airway function after weight loss in patients with obstructive sleep apnea. Am Rev Respir Dis 1988;138:1192–5. Rubinstein I, Hoffstein V, Bradley TD. Lung volume-related changes in the pharyngeal area of obese females with and without obstructive sleep apnoea. Eur Respir J 1989;2:344–51. Enzi G, Baggio B, Vianello A et al. Respiratory disturbances in visceral obesity. Int J Obes 1990;14:26. Muls E, Vryens C, Michels A et al. The effects of abdominal fat distribution measured by computed tomography on the respiratory system in non-smoking obese women. Int J Obes 1990;14:136. Dempsey JA, Reddan W, Balke B et al. Work capacity determinants and physiologic cost of weight-supported breathing in obesity. J Appl Physiol 1966;21:1815–20. Don HG, Crain DB, Wahbo WM et al. The measurement of gas trapped in the lungs at functional residual capacity and the effects of posture. Anesthesiology 1971;35:582–90. Holley HS, Milic-Emili J, Becklake MR et al. Regional distribution of pulmonary ventilation and perfusion in obesity. J Clin Invest 1967;46:475–81. Katz I, Stradling J, Slutsky AS, Zamel N, Hoffstein V. Do patients with obstructive sleep apnea have thick necks? Am Rev Respir Dis 1990;141:1228–31. Pressman MR, Meyer TJ, Kendrick-Mohamed J, Figueroa WG, Greenspon LW, Peterson DD. Night terrors in an adult precipitated by sleep apnea. Sleep 1995;18:773–5. Ferguson KA, Ono T, Lowe AA, Ryan CF, Fleetham JA. The relationship between obesity and craniofacial structure in obstructive sleep apnea. Chest 1995;108:375–81.
52. Shepard JWJ, Gefter WB, Guilleminault C et al. Evaluation of the upper airway in patients with obstructive sleep apnea. Sleep 1991;14:361–71. 53. deBerry-Borowiecki B, Kukwa A, Blanks RH. Cephalometric analysis for diagnosis and treatment of obstructive sleep apnea. Laryngoscope 1988;98:226–34. 54. Bacon WH, Krieger J, Turlot JC, Stierle JL. Craniofacial characteristics in patients with obstructive sleep apnea syndrome. Cleft Palate J 1988;25:374–8. 55. Strelzow VV, Blanks RH, Basile A, Strelzow AE. Cephalometric airway analysis in obstructive sleep apnea syndrome. Laryngoscope 1988;98:1149–58. 56. Partinen M, Guilleminault C, Quera-Salva MA, Jamieson A. Obstructive sleep apnea and cephalometric roentgenograms. The role of anatomic upper airway abnormalities in the definition of abnormal breathing during sleep. Chest 1988;93:1199–205. 57. Davies RJ, Ali NJ, Stradling JR. Neck circumference and other clinical features in the diagnosis of the obstructive sleep apnoea syndrome. Thorax 1992;47:101–5. 58. Grunstein R, Wilcox I, Yang TS, Gould Y, Hedner J. Snoring and sleep apnoea in men: association with central obesity and hypertension. Int J Obes Relat Metab Disord 1993;17:533–40. 59. Davies RJ, Stradling JR. The relationship between neck circumference, radiographic pharyngeal anatomy, and the obstructive sleep apnoea syndrome. Eur Respir J 1990;3:509–14. 60. Colt HG, Haas H, Rich GB. Hypoxemia vs sleep fragmentation as cause of excessive daytime sleepiness in obstructive sleep apnea. Chest 1991;100:1542–8. 61. Findley LJ, Unverzagt ME, Suratt PM. Automobile accidents involving patients with obstructive sleep apnea. Am Rev Respir Dis 1988;138:337–40. 62. Young T, Blustein J, Finn L, Palta M. Sleepdisordered breathing and motor vehicle
References
63.
64.
65.
66.
67.
68.
69.
70.
71.
72.
accidents in a population-based sample of employed adults. Sleep 1997;20:608–13. Guilleminault C, Connolly S, Winkle R, Melvin K, Tilkian A. Cyclical variation of the heart rate in sleep apnoea syndrome. Mechanisms, and usefulness of 24 h electrocardiography as a screening technique. Lancet 1984;1:126–31. Miller WP. Cardiac arrhythmias and conduction disturbances in the sleep apnea syndrome. Prevalence and significance. Am J Med 1982;73:317–21. Guilleminault C, Connolly SJ, Winkle RA. Cardiac arrhythmia and conduction disturbances during sleep in 400 patients with sleep apnea syndrome. Am J Cardiol 1983;52:490–4. Shepard JWJ, Garrison MW, Grither DA, Dolan GF. Relationship of ventricular ectopy to oxyhemoglobin desaturation in patients with obstructive sleep apnea. Chest 1985;88:335–40. Vincken W, Guilleminault C, Silvestri L, Cosio M, Grassino A. Inspiratory muscle activity as a trigger causing the airways to open in obstructive sleep apnea. Am Rev Respir Dis 1987;135:372–7. Gleeson K, Zwillich CW, White DP. The influence of increasing ventilatory effort on arousal from sleep. Am Rev Respir Dis 1990;142:295–300. Guilleminault C, Stoohs R, Clerk A, Cetel M, Maistros P. A cause of excessive daytime sleepiness: the upper airway resistance syndrome. Chest 1993;104:781–7. Loube DI, Gay PC, Strohl KP, Pack AI, White DP, Collop NA. Indications for positive airway pressure treatment of adult obstructive sleep apnea patients: a consensus statement. Chest 1999;115:863–6. Hung J, Whitford EG, Parsons RW, Hillman DR. Association of sleep apnoea with myocardial infarction in men. Lancet 1990;336:261–4. Partinen M, Guilleminault C. Daytime sleepiness and vascular morbidity at seven-
73.
74.
75.
76.
77.
78.
79.
80. 81.
82.
83.
19
year follow-up in obstructive sleep apnea patients. Chest 1990;97:27–32. Young T, Peppard P, Palta M et al. Population-based study of sleep-disordered breathing as a risk factor for hypertension. Arch Intern Med 1997;157:1746–52. He J, Kryger MH, Zorick FJ, Conway W, Roth T. Mortality and apnea index in obstructive sleep apnea. Experience in 385 male patients. Chest 1988;94:9–14. Bokinsky G, Miller M, Ault K, Husband P, Mitchell J. Spontaneous platelet activation and aggregation during obstructive sleep apnea and its response to therapy with nasal continuous positive airway pressure. A preliminary investigation. Chest 1995;108:625–30. Rangemark C, Hedner JA, Carlson JT, Gleerup G, Winther K. Platelet function and fibrinolytic activity in hypertensive and normotensive sleep apnea patients. Sleep 1995;18:188–94. Eisensehr I, Ehrenberg BL, Noachtar S et al. Platelet activation, epinephrine, and blood pressure in obstructive sleep apnea syndrome. Neurology 1998;51:188–95. The International Classification of Sleep Disorders: Diagnostic and Coding Manual. Rochester: American Sleep Disorders Association, 1990. Kribbs NB, Getsy JE, Dinges DF. Investigation and management of daytime sleepiness in sleep apnea. In: Saunders NA, Sullivan CE, eds. Sleeping and Breathing. New York: Marcel Dekker, 1993:575–604. Walsleben JA. The measurement of daytime wakefulness. Chest 1992;101:890–1. Wedderburn AA. Sleeping on the job: the use of anecdotes for recording rare but serious events. Ergonomics 1987;30:1229–33. Hoffstein V, Szalai JP. Predictive value of clinical features in diagnosing obstructive sleep apnea. Sleep 1993;16:118–22. Viner S, Szalai JP, Hoffstein V. Are history and physical examination a good screening test for sleep apnea? Ann Intern Med 1991;115:356–9.
20
Obstructive sleep apnea: the syndrome
84. Kapuniai LE, Andrew DJ, Crowell DH, Pearce JW. Identifying sleep apnea from selfreports. Sleep 1988;11:430–6. 85. Gyulay S, Olson LG, Hensley MJ, King MT, Allen KM, Saunders NA. A comparison of clinical assessment and home oximetry in the diagnosis of obstructive sleep apnea. Am Rev Respir Dis 1993;147:50–3. 86. Crocker BD, Olson LG, Saunders NA et al. Estimation of the probability of disturbed breathing during sleep before a sleep study. Am Rev Respir Dis 1990;142:14–18. 87. Flemons WW, Whitelaw WA, Brant R, Remmers JE. Likelihood ratios for a sleep apnea clinical prediction rule. Am J Respir Crit Care Med 1994;150:1279–85. 88. Kushida CA, Efron B, Guilleminault C. A predictive morphometric model for the obstructive sleep apnea syndrome. Ann Intern Med 1997;127:581–7.
89. Burrows B, Strauss RH, Niden AH. Chronic obstructive lung disease: 3. Interrelationships of pulmonary function data. Am Rev Respir Dis 1965;91:861. 90. Harvey RM, Enson Y, Ferrer MI. A reconsideration of the origins of pulmonary hypertension. Chest 1971;59:82. 91. Enson Y, Giuntini C, Lewis ML et al. The influence of hydrogen ion concentration and hypoxia on the pulmonary circulation. J Clin Invest 1964;43:1146. 92. Enson Y, Thomas HMI, Bosken CH et al. Pulmonary hypertension in interstitial lung disease: relation of vascular resistance to abnormal lung structure. Trans Assoc Am Physicians 1975;88:248. 93. Ungerer RG, Tahskin DP, Furst D et al. Prevalence and clinical correlates of pulmonary arterial hypertension in progressive systemic sclerosis. Am J Med 1983;75:65.
2 Non-apneic causes of excessive daytime sleepiness Mark W Mahowald
Introduction There is a tendency to equate the complaint of excessive daytime sleepiness (EDS) with the diagnosis of obstructive sleep apnea (OSA). In fact, OSA is only one of many causes of EDS, and often coexists with and may serve to confound other primary sleep disorders. This is important to recognize, as asymptomatic or coincidental OSA may be identified in patients with other causes of EDS, and may serve to mislead the sleep clinician, resulting in an erroneous diagnosis and ineffective treatment recommendations. Although clinically significant OSA may affect 2–4% of the adult population, observed, but possibly clinically insignificant or confounding OSA may be present in up to 9% of women and 24% of men.1 This means that at least 9–24% of patients who complain of EDS due to other causes will be found to have some degree of OSA upon formal evaluation. However, that degree of OSA may not be sufficient to explain the EDS. The presence of OSA on a sleep study performed on a patient complaining of EDS does not automatically establish cause and effect. It is the sleep professional’s responsibility to determine whether the degree of apnea identified is sufficient to
Case example 1 A 61-year-old, 1.73-m-tall, 158-lb school administrator was evaluated for a long history of severe excessive daytime sleepiness. He had none of the ancillary symptoms of narcolepsy. Polysomnography (PSG) revealed a respiratory disturbance index (RDI) of 22/h, with lowest hemoglobin oxygen saturation of 91%. The obstructive sleep apnea responded nicely to nasal continuous positive airway pressure (CPAP) 7 cm H2O pressure, with no clinical improvement. A repeat sleep study, while using nasal CPAP, confirmed CPAP effectiveness. A multiple sleep latency test (MSLT) the next day revealed a mean sleep latency of 3.0 min, with REM sleep on none of the naps. The true cause of his EDS was longstanding monosymptomatic narcolepsy or idiopathic central nervous system (CNS) hypersomnia, with coincidental OSA. In retrospect, his mild OSA was clearly an inadequate explanation for his longstanding, severe EDS. He responded well to stimulant medication.
22
Non-apneic causes of excessive daytime sleepiness
explain the severity of the patient’s EDS complaint, or whether the apnea is coincidental or contributory to another underlying cause of EDS, such as sleep deprivation or one of the many other medical causes of EDS.
Excessive daytime sleepiness—prevalence and consequences The prevalence of EDS is between 0.3% and 31%.2–5 The complaint of EDS should be taken very seriously, as there are serious consequences, including impaired psychosocial functioning, accidents, reduced work/school performance, and economic and public health consequences.4,6 As more data become available, state and national transportation and labor officials are appropriately becoming more interested in and concerned with the true consequences of EDS in the workplace and behind the wheel. Private and commercial vehicle crashes are frequently due to sleepiness. Factors involved include: sleep deprivation, underlying sleep disorders, duration of drive, and circadian rhythm influences. For the driver, there is a striking and distressing lack of awareness of the precursors to falling asleep.7–9 It is likely that the true incidence of fall-asleep motor vehicle crashes is far greater than reported.10 To add perspective, one full night of sleep deprivation is as impairing for driving as a legally intoxicating blood alcohol level.11 True EDS is always the manifestation of underlying physiologic sleepiness, and, contrary to popular opinion, is rarely, if ever, due to psychological or psychiatric conditions such as depression, laziness, boredom, workavoidance behavior, or other character defects.
In the absence of sleep deprivation, daytime hypersomnia is almost inevitably due to an identifiable and treatable sleep disorder such as sleep apnea, narcolepsy, or idiopathic CNS hypersomnia. Regrettably, despite the high prevalence and dire personal, societal and socio-economic consequences of EDS, a sleep history is routinely ignored in medical practice.12
Evaluation of EDS Evaluation of sleep physiology Polysomnography (PSG)
The technology used for the physiologic diagnosis of sleep disorders employs standard electrophysiologic recording systems and is thoroughly discussed in Chapter 4. Actigraphy
Analysis of sleep diaries may be insufficient to verify a tentative diagnosis in patients with reported insomnia or suspected wake–sleep cycle abnormalities. In such cases, definitive objective data may be obtained by actigraphy, a recently developed technique to record activity during wake and sleep that supplements the subjective sleep log. An actigraph is a small wrist-mounted device which records the activity plotted against time, usually for a week or two. When data collection has been completed, the results are transferred into a personal computer, where software displays activity versus time, demonstrating the rest–activity pattern at a glance. There is direct correlation between the rest–activity recorded by the actigraph and the wake–sleep pattern as determined by PSG.13 Indications for the use of actigraphy include: insomnia, wake–sleep
Evaluation of EDS schedule disorders, and monitoring treatment progress.14,15
Evaluation of daytime alertness–sleepiness Subjective (Sleepiness scales)
Subjective introspective alertness–sleepiness scales such as the Stanford Sleepiness Scale and the Epworth Sleepiness Scale (ESS) have been developed.16,17 The ESS is frequently used as a screening tool for identifying excessive daytime sleepiness, and generally correlates with other measures of sleep propensity.18,19 It must be remembered that such instruments are limited by their lack of sensitivity: there may be a striking discrepancy between the selfperceived sleepiness and the underlying true physiologic sleepiness in a given individual.20,21 In one study, neither patient nor partner ESS ratings were strong predictors of the degree of sleep apnea severity.22 Subjective sleepiness scales may be an inaccurate surrogate for true daytime sleepiness.
23
in quantifying daytime sleepiness and in differentiating the subjective complaints of ‘sleepiness’, ‘tiredness’ and ‘fatigue’. Single nap studies are inadequate, and MSLTs must always be preceded by a formal PSG to document the quality and quantity of sleep immediately preceding the MSLT. In difficult cases, it may be helpful to have 1 week of sleep diaries or actigraphic monitoring preceding the PSG/MSLT to ensure adequate sleep prior to the studies. (See case example 2). It must be remembered that falsely negative MSLTs can and do occur, and that there may be a discrepancy between the subjective complaint of sleepiness and the results of the MSLT.27,28 Stating that a patient does not have EDS on the basis of a ‘normal’ MSLT is analogous to stating that a patient with chest pain does not have cardiac disease on the basis of a normal EKG. Importantly, REM sleep may also occur in subjects with no complaints of excessive daytime sleepiness.29 Clearly, the PSG/MSLT results must be interpreted in light of the entire clinical setting. Maintenance of Wakefulness Test
Objective
Numerous methods have been developed to measure physiologic sleepiness during the waking period.23 Multiple Sleep Latency Test
The MSLT is discussed elsewhere in Chapter 4. Many factors can affect sleep latency during the daytime: prior sleep deprivation, sleep continuity, age, time of day, and medication.24–26 Proper interpretation requires a PSG the preceding night to measure the quality and quantity of sleep obtained immediately prior to the MSLT. The MSLT is a most useful tool
The maintenance of wakefulness test (MWT) is a variation of the MSLT. Unlike during the MSLT, the subject during the MWT is asked to resist sleep while sitting in a chair, rather than asked to fall asleep while lying in bed.30 The MWT appears to offer no specific advantage over the MSLT.31 Alpha Attenuation Test
This is a recently described technique to evaluate daytime sleepiness, based upon the fact that EEG power in the alpha frequency range decreases with eyes closed. The ratio of mean eyes-closed to mean eyes-open alpha power
24
Non-apneic causes of excessive daytime sleepiness
during seated wakefulness is smaller in sleepy subjects.32 Acceptance of this procedure will depend upon more extensive validation studies.
limitations, and, as with many other tests in medicine, the results of either must be interpreted in light of the specific clinical situation.19,34
Pupillography
Static pupillography is based on the fact that the pupils constrict during sleep. The rate of pupillary constriction is determined, and is felt to reflect the degree of underlying sleepiness.33 Pupillography is used infrequently in the evaluation of EDS, as it may be difficult to perform and interpret, and gives no indication as to the cause of the sleepiness. It is clear that all currently available subjective and objective measures of sleepiness have
Case example 2 An 18-year-old female with a remote history of severe depression had undergone two formal sleep studies for the complaint of severe EDS which was destroying her high school career. The first revealed a normal PSG, followed by an MSLT with a very short sleep latency ( 50 mmHg; as % TST) State with most obstruction Arousals Sleep architecture
Children
Adults
Cyclic apneas or obstructive hypoventilation Any
Cyclic apneas > 10 s
>1
>5
< 92
< 90
53 > 10%
?a ?a
REM +/– Preserved
REM or non-REM ++ Fragmented
a
Normative data on PCO2 during sleep in adults are not well established. TST, total sleep time; PETCO2, end-tidal PCO2.
have shown that reviewing audiotapes16,26 or videotapes27 of the sleeping child, in addition to the clinical evaluation, does not provide sufficient specificity to confirm the diagnosis of OSAS. Polysomnography has been shown to be cost-effective.22 Nonetheless, many otolaryngologists do not obtain sleep studies prior to surgery, citing such difficulties as cost or lack of available pediatric sleep centers.28,29 With time, more pediatric facilities will hopefully become available. Polysomnography
Polysomnography remains the gold standard for diagnosing OSAS in children.25 With the use of appropriate equipment and personnel, polysomnography can be performed successfully during natural sleep in infants and children of all ages. Provision should be made
for a parent to stay with the child. Vigilant technical support is necessary, as children frequently displace monitoring leads. There are several polysomnographic differences between children with OSAS and adults (Table 3.3). 1. Sleep architecture. Children with OSAS are less likely to have fragmented sleep than adults. In adults, obstructive apneas are usually terminated by cortical arousal. This is a protective mechanism that minimizes gas exchange abnormalities, but results in fragmented sleep, with diminished slow-wave and REM sleep, and resultant daytime sleepiness.30,31 In contrast, children with OSAS frequently do not have cortical arousals associated with obstructive apnea; the younger the child, the fewer the arousals.32 As a result, sleep architecture is preserved,17,33 and
Diagnostic considerations
45
Figure 3.2 All-night summary of a polysomnogram from an 8-yearold child with obstructive sleep apnea. Each apnea is designated by a vertical line. Time is represented on the X-axis. Note that apneas and episodes of arterial oxygen desaturation occur almost exclusively during REM sleep (depicted as the bold bars on the hypnogram). WK, wake; S1–4, sleep stages 1–4, respectively.
daytime sleepiness is uncommon.34 However, there is evidence that children with OSAS may have subcortical arousals,35 which can result in autonomic sequelae such as heart rate changes36 and hypertension.20 2. In children, obstructive apnea is predominantly an REM phenomenon (Figure 3.2).37,38 A recent study of children with severe OSAS showed that the majority of obstructive apneas occurred during REM sleep, although REM sleep accounted for less than a quarter of total sleep time.38 Furthermore, apneas were longer and more numerous during later REM periods than during REM periods earlier in the night. The clinical significance of this finding is that sleep-disordered breathing may be missed if REM time is decreased or absent on screening studies, such as nap studies or on home audio/videotapes.
3. Children may show a pattern of persistent, partial upper airway obstruction associated with hypercapnia and/or hypoxemia, rather than cyclic discrete obstructive apnea (Figures 3.3 and 3.4). This has been termed ‘obstructive hypoventilation’.25 OH is seen most commonly in younger children, perhaps because their high arousal threshold allows for long periods of partial obstruction. Clinically, these children are difficult to diagnose, as they have a history of constant snoring, which is not interrupted by pauses or gasps. However, their parents frequently describe labored breathing during sleep. OH is diagnosed by the presence of episodic elevated end-tidal PCO2 levels in association with snoring and paradoxical breathing. Episodes may be very long (hours). In order to detect obstructive hypoventilation, it is important to monitor the end-tidal PCO2 (PETCO2)
46
Obstructive sleep apnea in children
Figure 3.3 A 2-min portion of a polysomnograph from an 8-year-old child is shown. There are multiple, discrete episodes of obstructive apnea (of up to 25 s duration) associated with cyclical desaturation (to 83%) and EEG arousals. This pattern is similar to that seen in adults with obstructive sleep apnea. LEOG, left electro-oculogram; REOG, right electro-oculogram; C3A2 and O1A2, EEG leads; Chin, submental EMG; NAF, oronasal airflow via a thermistor; THO, thoracic wall movement; ABD, abdominal wall movement; CO2, end-tidal PCO2 waveform; PULSE, oximeter pulse waveform; LEMG, tibial EMG. Time is shown on the X-axis.
Figure 3.4 A 30-s portion of a polysomnograph from a 2year-old child with obstructive hypoventilation is shown. There are no discrete episodes of obstructive apnea, and no evidence of cortical arousal. Paradoxical inward motion of the chest wall during inspiration is present. This is associated with persistent hypercapnia (end-tidal PCO2 (EtCO2) in the 60s) and arterial oxygen desaturation (SaO2 77–85%). Abbreviations as for Figure 3.3.
Diagnostic considerations during pediatric polysomnography. When scoring sleep studies, it should be remembered that normal PCO2 levels are higher during sleep than during wakefulness. A study of normal children showed that a peak PETCO2 > 53 mmHg during sleep is abnormal.39 A more important parameter to measure is the duration of hypoventilation. A PETCO2 > 50 mmHg for more than 10% of total sleep time is abnormal.39 4. Pediatric sleep studies need to be scored and interpreted differently from adult studies. Breathing during sleep changes with age. Therefore, the standards used for the interpretation of polysomnography in adults cannot be extrapolated to infants and children. Children appear to have clinical sequelae associated with milder forms of OSAS than adults, i.e. with fewer and shorter obstructive apneas. The reason for this is unclear, but may be that significant desaturation can occur even with brief apneas. This is because children have a lower functional residual capacity and a faster respiratory rate than adults. The details for pediatric scoring are outlined in the American Thoracic Society consensus statement.25 In adults, apneas > 10s in duration are scored, whereas in children, obstructive apneas of any length are quantitated. For convenience, our laboratory scores obstructions that are two or more respiratory cycles in length. In adults, an apnea index > 5–10/h is considered abnormal. Based on normative data,39 an obstructive apnea index > 1 is considered abnormal in children. However, while an apnea index greater than one is statistically significant, it is not known what level is clinically significant.40 There are no normative data for hypopneas in young children. An arterial oxygen saturation of 92% is considered the lower
47
limit of normal.39 However, it is not uncommon for normal children to have transient desaturation below this level, often in association with central apnea or periodic breathing.41 The upper airway resistance syndrome (UARS) may occur in children.42 Currently, it is diagnosed by measuring the esophageal pressure during polysomnography. Less invasive diagnostic techniques are being developed.43
Nap studies
Daytime nap polysomnography is an alternative to overnight polysomnography. Nap studies, if positive, are highly suggestive of OSAS. However, nap polysomnography has a high false-negative rate and frequently underestimates the degree of sleep-disordered breathing.44 Nap polysomnography is of shorter duration, may not include REM sleep, and may be altered by circadian variations in sleep patterns. In addition, sedation or sleep deprivation, both of which can affect polysomnography results, are frequently necessary to induce sleep.
Home sleep studies
The utility of home or unattended sleep studies has not been well studied in children. Success has been reported from one center.45 However, the polysomnography system used in this study consisted of seven channels in conjunction with videotaping, and is not analogous to commercially available systems. Furthermore, few patients with moderate to severe OSAS were studied. Home studies are potentially advantageous, as they are less disruptive for the patient and family, and may make
48
Obstructive sleep apnea in children
polysomnography more accessible and cheaper. Potential problems include lead displacement, inability to monitor for OH or UARS, and the lack of monitoring for REM sleep with most systems.
Pulse oximetry
Nocturnal pulse oximetry has been evaluated as a screening tool for OSAS.13,46–48 It may be useful if it shows a pattern of cyclic desaturation; however, there is a high false-negative rate. Furthermore, it will miss those children who have obstructive apneas without significant desaturation, but with increased work of breathing or sleep fragmentation.
Ancillary studies
In most children, radiologic evaluation of the upper airway is unnecessary. The tonsils can be evaluated clinically, and the adenoids can be assessed at the time of surgery or via endoscopy. In patients with complex craniofacial anomalies, upper airway endoscopy, cephalometry or CT scans may be helpful to delineate the anatomy and help plan the surgical approach. Patients with severe OSAS should be assessed for pulmonary hypertension by chest X-ray and EKG or echocardiography. Formal testing of cognitive function or assessment of hyperactivity may be appropriate for individual patients.
Treatment considerations
children with severe OSAS should always be treated. On the other hand, there is no evidence that children with primary snoring benefit from treatment. However, children with mild degrees of OSAS present a dilemma. Little is known about the natural course of untreated, mild OSAS in children. Furthermore, it is not known which polysomnographic parameters predict morbidity, and hence what degree of OSAS merits treatment.40 Further study is clearly needed. In the interim, treatment decisions should be based on the constellation of symptoms, physical examination and polysomnography. As most children initially present because they are symptomatic, and as we have seen a number of children with progressive OSAS, but none with spontaneous resolution of OSAS, our tendency is to treat many of the children with mild disease.
Emergency stabilization and treatment Most children with OSAS have been symptomatic for some time prior to diagnosis, and can await elective treatment. Occasionally, a child presents with severe hypoxemia, heart failure, respiratory failure or an altered level of consciousness. In an emergency situation, the patient can be treated with nasopharyngeal tubes that are passed to the level of the tonsils.49 Alternatively, continuous positive airway pressure (CPAP) can be used pending definitive treatment.
When to treat
Tonsillectomy and adenoidectomy
It is not clear which children with sleep-disordered breathing need to be treated. Certainly,
The cardinal treatment for childhood OSAS is tonsillectomy and adenoidectomy (T&A).
Treatment considerations OSAS results from the relative size and structure of the upper airway components, rather than the absolute size of the adenotonsillar tissue. Therefore, both tonsils and adenoids should be removed, even if one or the other appears to be the primary abnormality. An exception is infants, in whom adenoidectomy alone may be sufficient. However, when necessary, T&A is safe and effective in this age group.50 By the same logic, T&A should be the initial treatment of OSAS in children with other predisposing factors, such as obesity51 or Down syndrome,52 although further treatment may be necessary. In children with a submucous cleft palate, adenoidectomy may result in velopharyngeal incompetence; in this group, tonsillectomy alone is a consideration. Although T&A is considered to be relatively minor surgery, significant complications may occur. It is for this reason that T&A is not recommended as treatment for primary snoring. Recent studies have demonstrated complication rates of 6–9%;53–55 complication rates are higher in children with OSAS. Potential complications include immediate perioperative problems (such as pain, dehydration and anesthetic complications), hemorrhage, postoperative respiratory compromise, nasopharyngeal stenosis, velopharyngeal incompetence and death. Postoperative respiratory compromise has been reported to occur in 16–27% of children with OSAS.56–58 The reasons for this include postoperative upper airway edema, increased secretions, respiratory depression secondary to analgesic and anesthetic agents, and postobstructive pulmonary edema.59 High-risk groups include children < 3 years of age, those with severe OSAS, and those with underlying diseases, such as craniofacial anomalies or cerebral palsy.56,57,60 These children are not candidates for outpatient surgery.
49
The majority of children with OSAS will improve postoperatively. Those with severe OSAS,4 or other underlying diseases, should undergo repeat polysomnography 6–8 weeks postoperatively, in order to ensure that additional treatment is not needed.
Continuous positive airway pressure Nasal CPAP is the mainstay of treatment for OSAS in the adult population. Although still not approved by the American Food and Drug Administration for use in children, reports in the literature describe its successful application in more than 266 infants and children.61–64 In our experience, CPAP is well tolerated and effective in the pediatric population, provided that appropriate counseling and support is provided. CPAP use in the young or developmentally delayed child may be difficult. In these cases, behavioral psychology techniques can be useful.65 Another problem with CPAP use in the pediatric population is a shortage of appropriately sized interfaces. Small or weak children may not be able to trigger bilevel or auto-CPAP devices. The sideeffects of CPAP in children are similar to those in adults, and include nasal symptoms, eye irritation or skin lesions. More serious potential side-effects, such as aspiration, pneumothorax or middle ear problems, have not been reported. Central apnea occurs quite commonly in children using CPAP, and is probably due to the prominent Hering–Breuer reflex seen in this age group. If necessary, this can be prevented by providing bilevel pressure with a backup rate. Anecdotal concerns of midfacial depression due to mask pressure have been raised, but definitive data are lacking. In children, unlike in adults, it is
50
Obstructive sleep apnea in children
necessary to frequently re-evaluate pressure levels, as these may change in association with growth of the airway and changes in the airway soft tissue.61 In addition, mask size needs to be evaluated with growth.
Weight loss Unlike adults, most children with OSAS are not obese. However, OSAS is common among morbidly obese children.66 The prevalence of childhood obesity is increasing. Currently, 10% of children in the US are obese.67 Weight loss in obese patients will result in an improvement in the degree of sleep-disordered breathing. However, weight reduction may be extraordinarily difficult for a child to achieve, particularly when the entire family is overweight. Fortunately, many obese children with OSAS will improve following T&A,51 which should be considered as initial treatment. For those obese patients in whom surgery is insufficient, CPAP treatment is indicated while the patient attempts to lose weight.
Uvulopharyngopalatoplasty (UPPP) Few studies have evaluated the safety and efficacy of UPPP in children. It is useful in patients in whom abnormal upper airway neuromuscular tone contributes to OSAS, e.g. patients with cerebral palsy68,69 or Down syndrome.70,71 In addition, it has been reported to be successful in the treatment of an otherwise normal 3-year-old child with OSAS.72 Currently, we would consider UPPP for children with OSAS unresponsive to either T&A or nasal CPAP, especially those children who are obese or have redundant oropharyngeal soft tissue. However, further study is needed.
Craniofacial surgery In patients with craniofacial anomalies, specific surgical procedures may be appropriate, such as supraglottoplasty in patients with severe laryngomalacia73 and mandibular distraction in children with micrognathia. Tongue wedge resection has been reported to be efficacious in patients with macroglossia (e.g. those with Down syndrome or Beckwith–Wiedemann syndrome).70,74
Supplemental oxygen Two studies have evaluated the use of supplemental oxygen in children with OSAS.75,76 Both studies showed an improvement in arterial oxygen saturation, without a worsening of apnea. However, although PCO2 levels did not change for the group as a whole, a few individuals developed significant hypercapnia when breathing supplemental oxygen. Although supplemental oxygen should not be used as a first-line treatment for OSAS, it may be useful in a few individuals in whom surgical or CPAP therapy is unsuccessful, providing that the patient’s PCO2 is monitored closely.
Pharmacologic treatment It is generally accepted that pharmacologic agents are not clinically useful in the management of OSAS in children. Topical treatment of allergic rhinitis can be a useful adjunct to definitive treatment. Although systemic steroids have been used to shrink adenoidal tissue, a recent controlled study showed no significant improvement in sleep-disordered breathing after a 5-day course of prednisone.77
References The use of sedative drugs should be avoided, as these may aggravate OSAS.
Oral appliances The use of oral appliances in the treatment of adults with OSAS is increasing. However, oral appliances have not been studied in detail in pediatric patients, due to the concern that they may adversely affect the facial configuration of the growing child. Some centers have advocated the use of rapid maxillary expansion to treat children with OSAS; however, objective data on this procedure are not yet available.
51
independent disease entity. There has been only one long-term study of childhood OSAS. Guilleminault et al8 re-evaluated adolescents who had been successfully treated with T&A during childhood, and found that a small percentage (13% of those who returned for follow-up) had a recurrence. All were male. This study suggests that either some or all children with OSAS and adenotonsillar hypertrophy have additional subclinical abnormalities, be they structural or neuromuscular, that can lead to recurrence of OSAS if additional risk factors (such as weight gain, or testosterone secretion at puberty) are acquired. Further study is needed.
Acknowledgments Tracheotomy Tracheotomy is the ultimate treatment for OSAS, as it bypasses the site of obstruction. However, it is associated with many complications, including speech problems, chronic tracheitis and interference with the activities of daily life. Fortunately, with the increased use of CPAP and other treatment modalities, tracheotomy is now rarely required for OSAS. It may be needed in children with upper airway obstruction during both wakefulness and sleep, particularly children with craniofacial anomalies or cerebral palsy.
Prognosis and natural course The natural course and long-term prognosis of childhood OSAS are not known. Specifically, it is not known whether childhood OSAS is a precursor of adult OSAS, or whether it is an
Dr Marcus was supported in part by the Pediatric Clinical Research Center #RR00052, the Johns Hopkins Hospital, Baltimore, MD, and NHLBI grant #HL58585-01.
References 1. Redline S, Tishler PV, Schluchter M, Aylor J, Clark K, Graham G. Risk factors for sleepdisordered breathing in children. Associations with obesity, race, and respiratory problems. Am J Respir Crit Care Med 1999;59:1527–32. 2. Gislason T, Benediktsdottir B. Snoring, apneic episodes, and nocturnal hypoxemia among children 6 months to 6 years old. Chest 1995;107:963–6. 3. Jeans WD, Fernando DCJ, Maw AR, Leighton BC. A longitudinal study of the growth of the nasopharynx and its contents in normal children. Br J Radiol 1981;54: 117–21. 4. Suen JS, Arnold JE, Brooks LJ. Adenotonsillectomy for treatment of
52
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
Obstructive sleep apnea in children obstructive sleep apnea in children. Arch Otolaryngol Head Neck Surg 1995;121:525–30. Fernbach SK, Brouillette RT, Riggs TW, Hunt CE. Radiologic evaluation of adenoids and tonsils in children with obstructive apnea: plain films and fluoroscopy. Pediatr Radiol 1983;13:258–65. Mahboubi S, Marsh RR, Potsic WP, Pasquariello PS. The lateral neck radiograph in adenotonsillar hyperplasia. Int J Pediatr Otorhinolaryngol 1985;10:67–73. Laurikainen E, Erkinjuntti M, Alihanka J, Rikalainen H, Suonpaa J. Radiological parameters of the bony nasopharynx and the adenotonsillar size compared with sleep apnea episodes in children. Int J Pediatr Otorhinolaryngol 1987;12:303–10. Guilleminault C, Partinen M, Praud JP, Quera-Salva MA, Powell N, Riley R. Morphometric facial changes and obstructive sleep apnea in adolescents. J Pediatr 1989;114:997–9. Kotagal S, Gibbons VP, Stith JA. Sleep abnormalities in patients with severe cerebral palsy. Dev Med Child Neurol 1994;36:304–11. Khan Y, Heckmatt JZ. Obstructive apnoeas in Duchenne muscular dystrophy. Thorax 1994;49:157–61. Ali NJ, Pitson DJ, Stradling JR. Snoring, sleep disturbance and behaviour in 4–5 year olds. Arch Dis Child 1993;68:360–6. Hultcrantz E, Lofstrand-Tidestrom B, AhlquistRastad J. The epidemiology of sleep related breathing disorder in children. Int J Pediatr Otorhinolaryngol 1995;32(suppl): S63–6. Owen GO, Canter RJ, Robinson A. Overnight pulse oximetry in snoring and nonsnoring children. Clin Otolaryngol 1995;20:402–6. Teculescu DB, Caillier I, Perrin P, Rebstock E, Rauch A. Snoring in French preschool children. Pediatr Pulmonol 1992;13:239–44. Carroll JL, McColley SA, Marcus CL, Curtis S, Loughlin GM. Inability of clinical history
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
to distinguish primary snoring from obstructive sleep apnea syndrome in children. Chest 1995;108:610–18. Goldstein NA, Sculerati N, Walsleben JA, Bhatia N, Friedman DM, Rapoport DM. Clinical diagnosis of pediatric obstructive sleep apnea validated by polysomnography. Otolaryngol Head Neck Surg 1994;111:611–17. Marcus CL, Carroll JL, Koerner CB, Hamer A, Lutz J, Loughlin GM. Determinants of growth in children with the obstructive sleep apnea syndrome. J Pediatr 1994;125:556–62. Gozal D. Sleep-disordered breathing and school performance in children. Pediatrics 1998;102:616–20. Brouillette RT, Fernbach SK, Hunt CE. Obstructive sleep apnea in infants and children. J Pediatr 1982;100:31–40. Marcus CL, Greene MG, Carroll JL. Blood pressure in children with obstructive sleep apnea. Am J Respir Crit Care Med 1998;157:1098–103. Nieminen P, Tolonen U, Lopponen H, Lopponen T, Luotonen J, Jokinen K. Snoring children: factors predicting sleep apnea. Acta Otolaryngol Suppl (Stockh) 1997;529:190–4. Wang RC, Elkins TP, Keech D, Wauquier A, Hubbard D. Accuracy of clinical evaluation in pediatric obstructive sleep apnea. Otolaryngol Head Neck Surg 1998;118:69–73. Leach J, Olson J, Hermann J, Manning S. Polysomnographic and clinical findings in children with obstructive sleep apnea. Arch Otolaryngol Head Neck Surg 1992;118: 741–4. American Sleep Disorders Association. Practice parameters for the treatment of obstructive sleep apnea in adults: the efficacy of surgical modifications of the upper airway. Sleep 1995;19:152–5. American Thoracic Society. Standards and indications for cardiopulmonary sleep studies in children. Am J Respir Crit Care Med 1996;153:866–78. Lamm C, Mandeli J, Kattan M. Evaluation of home audiotapes as an abbreviated test for
References
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
obstructive sleep apnea syndrome (OSAS) in children. Pediatr Pulmonol 1999;27:267–72. Sivan Y, Kornecki A, Schonfeld T. Screening obstructive sleep apnoea syndrome by home videotape recording in children. Eur Respir J 1996;9:2127–31. Messner AH. Evaluation of obstructive sleep apnea by polysomnography prior to pediatric adenotonsillectomy. Arch Otolaryngol Head Neck Surg 1999;125:353–6. Pelayo R, Powell N. Evaluation of obstructive sleep apnea by polysomnography prior to pediatric adenotonsillectomy. Arch Otolaryngol Head Neck Surg 1999;125:1282–3. Weitzman ED, Kahn E, Pollak CP. Quantitative analysis of sleep and sleep apnea before and after tracheostomy in patients with the hypersomnia–sleep apnea syndrome. Sleep 1980;3:407–23. Bradley TD, Phillipson EA. Pathogenesis and pathophysiology of the obstructive sleep apnea syndrome. Med Clin North Am 1985;69:1169–85. McNamara F, Issa FG, Sullivan CE. Arousal pattern following central and obstructive breathing abnormalities in infants and children. J Appl Physiol 1996;81:2651–7. Frank Y, Kravath RE, Pollak CP, Weitzman ED. Obstructive sleep apnea and its therapy; clinical and polysomnographic manifestations. Pediatrics 1983;71:737–42. Carroll JL, Loughlin GM. Obstructive sleep apnea syndrome in infants and children: clinical features and pathophysiology. In: Ferber R, Kryger M, eds. Principles and Practice of Sleep Medicine in the Child. Philadelphia: WB Saunders, 1995:163–91. Mograss MA, Ducharme FM, Brouillette RT. Movement/arousals. Description, classification, and relationship to sleep apnea in children. Am J Respir Crit Care Med 1994;150:1690–6. Aljadeff G, Gozal D, Schechtman VL, Burrell B, Harper RM, Ward SL. Heart rate variability in children with obstructive sleep apnea. Sleep 1997;20:151–7.
53
37. Morielli A, Ladan S, Ducharme FM, Brouillette RT. Can sleep and wakefulness be distinguished in children by cardiorespiratory and videotape recordings? Chest 1996;109:680–7. 38. Goh DYT, Galster PMCL. Sleep architecture and respiratory disturbances in children with obstructive sleep apnea. Am J Respir Crit Care Med 2000;162:682–6. 39. Marcus CL, Omlin KJ, Basinki DJ et al. Normal polysomnographic values for children and adolescents. Am Rev Respir Dis 1992;146:1235–9. 40. American Thoracic Society. Cardiorespiratory sleep studies in children: establishment of normative data and polysomnographic predictors of morbidity. Am J Respir Crit Care Med 1999;160:1381–7. 41. Poets CF, Stebbens VA, Samuels MP, Southall DP. Oxygen saturation and breathing patterns in children. Pediatrics 1993;92:686–90. 42. Guilleminault C, Pelayo R, Leger D, Clerk A, Bocian RC. Recognition of sleep-disordered breathing in children. Pediatrics 1996;98:871–82. 43. Katz ES, Marcus C. The pulse transit time as a measure of arousal and respiratory effort in children with sleep-disordered breathing. Am J Respir Crit Care Med 2000;161:A806. 44. Marcus CL, Keens TG, Ward SL. Comparison of nap and overnight polysomnography in children. Pediatr Pulmonol 1992;13:16–21. 45. Jacob SV, Morielli A, Mograss MA, Ducharme FM, Schloss MD, Brouillette RT. Home testing for pediatric obstructive sleep apnea syndrome secondary to adenotonsillar hypertrophy. Pediatr Pulmonol 1995;20:241–52. 46. Brouillette RT, Morielli A, Leimanis A, Waters KA, Luciano R, Ducharme FM. Nocturnal pulse oximetry as an abbreviated testing modality for pediatric obstructive sleep apnea. Pediatrics 2000;105:405–12. 47. Stradling JR, Thomas G, Warley AR, Williams P, Freeland A. Effect of
54
48.
49.
50.
51.
52.
53.
54.
55.
56.
57.
Obstructive sleep apnea in children adenotonsillectomy on nocturnal hypoxaemia, sleep disturbance, and symptoms in snoring children. Lancet 1990;335:249–53. van Someren VH, Hibbert J, Stothers JK, Kyme MC, Morrison GAJ. Identifying hypoxaemia in children admitted for adenotonsillectomy. BMJ 1989;298:1076. Kravath RE, Pollak CP, Borowiecki B. Hypoventilation during sleep in children who have lymphoid airway obstruction treated by nasopharyngeal tube and T and A. Pediatrics 1977;59:865–71. Leiberman A, Tal A, Brama I, Sofer S. Obstructive sleep apnea in young infants. Int J Pediatr Otorhinolaryngol 1988;16:39–44. Kudoh F, Sanai A. Effect of tonsillectomy and adenoidectomy on obese children with sleepassociated breathing disorders. Acta Otolaryngol 1996; Suppl 523:216–18. Marcus CL, Keens TG, Bautista DB, Von Pechmann WS, Ward SL. Obstructive sleep apnea in children with Down syndrome. Pediatrics 1991;88:132–9. Nicklaus PJ, Herzon FS, Steinle EW. Shortstay outpatient tonsillectomy. Arch Otolaryngol Head Neck Surg 1995;121:521–4. Kendrick D, Gibbin K. An audit of the complications of paediatric tonsillectomy, adenoidectomy and adenotonsillectomy. Clin Otolaryngol 1993;18:115–17. Reiner SA, Sawyer WP, Clark KF, Wood MVV. Safety of outpatient tonsillectomy and adenoidectomy. Otolaryngol Head Neck Surg 1990;102:161–8. Rosen GM, Muckle RP, Mahowald MW, Goding GS, Ullevig C. Postoperative respiratory compromise in children with obstructive sleep apnea syndrome: can it be anticipated? Pediatrics 1994;93:784–8. McColley SA, April MM, Carroll JL, Loughlin GM. Respiratory compromise after adenotonsillectomy in children with obstructive sleep apnea. Arch Otolaryngol Head Neck Surg 1992;118:940–3.
58. Ruboyianes JM, Cruz RM. Pediatric adenotonsillectomy for obstructive sleep apnea. Ear Nose Throat J 1996;75:430–3. 59. Galvis AJ. Pulmonary edema complicating relief of upper airway obstruction. Am J Emerg Med 1987;5:294–7. 60. Wiatrak BJ, Myer CM, Andrews TM. Complications of adenotonsillectomy in children under 3 years of age. Am J Otolaryngol 1991;12:170–2. 61. Marcus CL, Ward SL, Mallory GB et al. Use of nasal continuous positive airway pressure as treatment of childhood obstructive sleep apnea. J Pediatr 1995;127:88–94. 62. Waters KA, Everett FM, Bruderer JW, Sullivan CE. Obstructive sleep apnea: the use of nasal CPAP in 80 children. Am J Respir Crit Care Med 1995;152:780–5. 63. Guilleminault C, Pelayo R, Clerk A, Leger D, Bocian RC. Home nasal continuous positive airway pressure in infants with sleep-disordered breathing. J Pediatr 1995;127:905–12. 64. McNamara F, Sullivan CE. Obstructive sleep apnea in infants and its management with nasal continuous positive airway pressure. Chest 1999;116:10–16. 65. Rains JC. Treatment of obstructive sleep apnea in pediatric patients. Clin Pediatr 1995;34:535–41. 66. Marcus CL, Curtis S, Koerner CB, Joffe A, Serwint JR, Loughlin GM. Evaluation of pulmonary function and polysomnography in obese children and adolescents. Pediatr Pulmonol 1996;21:176–83. 67. Mei Z, Scanlon KS, Grummer-Strawn LM, Freedman DS, Yip R, Trowbridge FL. Increasing prevalence of overweight among US low-income preschool children: the Centers for Disease Control and Prevention pediatric nutrition surveillance, 1983 to 1995. Pediatrics 1998;101:12. 68. Kosko JR, Derkay CS. Uvulopalatopharyngoplasty: treatment of obstructive sleep apnea in neurologically impaired pediatric patients. Int J Pediatr Otorhinolaryngol 1995;32:241–6.
References 69. Seid AB, Martin PJ, Pransky SM, Kearns DB. Surgical therapy of obstructive sleep apnea in children with severe mental insufficiency. Laryngoscope 1990;100:507–10. 70. Donaldson JD, Redmond WM. Surgical management of obstructive sleep apnea in children with Down syndrome. J Otolaryngol 1988;17:398–403. 71. Strome M. Obstructive sleep apnea in Down syndrome children: a surgical approach. Laryngoscope 1986;96:1340–2. 72. Abdu MH, Feghali JG. Uvulopalatopharyngoplasty in a child with obstructive sleep apnea. A case report. J Laryngol Otol 1988;102:5465–8. 73. Marcus CL, Crockett DM, Ward SL. Evaluation of epiglottoplasty as treatment for severe laryngomalacia [published erratum appears in J Pediatr 1991;118(1):168]. J Pediatr 1990;117:706–10.
55
74. Morgan WE, Friedman EM, Duncan NO, Sulek M. Surgical management of macroglossia in children. Arch Otolaryngol Head Neck Surg 1996;122:326–9. 75. Marcus CL, Carroll JL, Bamford O, Pyzik P, Loughlin GM. Supplemental oxygen during sleep in children with sleep-disordered breathing. Am J Respir Crit Care Med 1995;152:1297–301. 76. Aljadeff G, Gozal D, Bailey-Wahl SL. Effects of overnight supplemental oxygen in obstructive sleep apnea in children. Am J Respir Crit Care Med 1996;153:51–5. 77. Al-Ghamdi SA, Manoukian JJ, Morielli A, Oudjhane K, Ducharme FM, Brouillette RT. Do systemic corticosteroids effectively treat obstructive sleep apnea secondary to adenotonsillar hypertrophy? Laryngoscope 1997;107:1382–7.
4 Diagnostic studies for sleep apnea/hypopnea Rajesh Jasani, Mark H Sanders and Patrick J Strollo Jr
Airflow Effort
Expiration Inspiration
Pes
Figure 4.1 Obstructive sleep apnea: apnea with continuing respiratory effort, as shown by progressively increasing fluctuations in esophageal pressure (Pes) associated with cessation of airflow. The arrow represents resumption of airflow which usually accompanies an arousal. Airflow
Obstructive sleep apnea–hypopnea syndrome (OSAHS) is a common disorder that represents a significant public health problem, affecting 2–4% of the middle-aged population with a wide range of severity.1,2 The clinical spectrum of OSAHS includes a number of different disorders, possibly resulting from different pathophysiologic mechanisms or representing different points along a continuum of upper airway dysfunction. Although the definition of apnea is unambiguous, identifying those events in which airflow is present but pathologically reduced (hypopnea) is more challenging. There is currently no universally accepted definition for hypopnea.3–6 The application of various clinical techniques possessing different sensitivities to record airflow and breathing effort has further contributed to heterogeneity across sleep laboratories in identifying abnormal breathing events, even when using the same definitions. Ultimate resolution of these issues must await standardization of recording techniques and studies assessing correlations between definitions and health outcomes. To facilitate patient care until this occurs, a task force of The American Academy of Sleep Medicine has recommended terminology and standards of practice for the recording of sleep
and breathing, and assigned evidence-based definitions for abnormal events, parameters and disorders as outlined below and in Figures 4.1–4.5 (‘Chicago Criteria’).7
Effort
Introduction
Expiration Inspiration
Pes
Figure 4.2 Central sleep apnea: cessation of airflow associated with no respiratory efforts, as shown by changes in esophageal pressure (Pes).
Apnea This is defined as cessation of airflow for 10 s or more. Apnea is divided into three patterns. Obstructive apnea
This is apnea during which there is ventilatory effort but no airflow, due to upper airway obstruction (Figure 4.1). Central apnea
This is apnea occurring in the absence of ventilatory effort (Figure 4.2).
Airflow
Diagnostic studies for sleep apnea/hypopnea
Effort
58
Expiration Inspiration
Apnea
Pes
Figure 4.3 Mixed apnea: apnea initially appears as a central apnea (without respiratory effort as evidenced by the constant esophageal pressure (Pes), followed by a period of obstructive apnea (with respiratory effort as evidenced by changes in esophageal pressure). The arrow represents arousal and termination of an event.
This is defined as an event which is characterized by disproportionate reduction of inspiratory airflow relative to inspiratory effort or metabolic needs. The American Academy of Sleep Medicine Task Force7 defined or characterized hypopnea as follows: ‘A clear decrease (> 50%) from baseline in the amplitude of a valid measure of breathing during sleep or an amplitude reduction (< 50%) associated with either an oxyhemoglobin desaturation (> 3%) or an arousal, and the event should last at least 10 seconds.’ Hypopneas, like apneas, can be central or obstructive, although this distinction is infrequently made when reporting clinical sleep studies (Figures 4.4 and 4.5). In routine clinical practice, it may not be necessary to
Effort
Expiration Inspiration
Pes
Figure 4.4 Obstructive sleep hypopnea: decrease in airflow associated with an increase in respiratory effort (Pes, esophageal pressure; arrow represents an arousal).
Airflow
Hypopnea
Effort
This is apnea which is initially due to absent ventilatory effort (a ‘central’ pattern), and subsequently persists despite resumption of ventilatory efforts (an ‘obstructive’ pattern) (Figure 4.3).
Airflow
Mixed apnea
Expiration Inspiration
Pes
Figure 4.5 Central sleep hypopnea: decrease in airflow associated with decrease in respiratory effort.
Introduction differentiate apneas from hypopneas when both types of events have similar pathophysiologic consequences, such as arousal and oxyhemoglobin desaturation.8–10 There are currently no data to suggest different long- or short-term outcome in patients with predominantly hypopneas as compared to apneas.
Apnea, hypopnea and apnea + hypopnea indices Dividing the total number of apneas during a recording period by the total sleep time yields the average number of apneas per hour of sleep, or apnea index (AI). Similarly a variety of other indices, including hypopnea index (HI) and apnea + hypopnea index (AHI) (also termed the respiratory disturbance index (RDI)) are usually employed to quantify OSAHS severity. The concept of ‘index’ permits standardization of event frequency for the number of hours slept. This facilitates comparison of individual patient data with normative as well as pre- and post-treatment values.
Obstructive sleep apnea–hypopnea syndrome The OSAHS is usually defined as excessive daytime somnolence and other sequelae attributable to frequent obstructive apneas or hypopneas during sleep. The criterion of an AHI * 5 is also frequently employed.7 The use of an event frequency of five per hour as a minimal threshold value has been based on epidemiologic data suggesting that adverse health effects, including hypertension, sleepiness and motor vehicle accidents, may be
59
observed at or above this threshold.11–13 Additionally, limited data from intervention studies suggest treatment-associated improvements in vitality, mood and fatigue in patients with AHI between 5 and 30,14 as well as improvement in sleepiness and neurocognitive function in patients with AHI levels of 5–15.15,16 The threshold of AHI that should be employed as a case-finding instrument for the diagnosis of OSAH probably varies with the age of the patient. As discussed in Chapter 3, the presence of one obstructive apnea per hour in a young child may be sufficient to make the diagnosis of obstructive sleep apnea.17–19 Thus, although there are no specific large epidemiologic studies defining the normal distribution of OSAH in the general population, AHI greater than 5–10 is considered to be beyond the broad limits of normal and may justify therapy, particularly in the presence of adverse physiologic or neurocognitive consequences, or attributable difficulty in maintaining alertness.
Upper airway resistance syndrome The upper airway resistance syndrome (UARS) is defined by repetitive and progressively increasing inspiratory efforts with subsequent transient arousal, but without associated reduction in airflow (i.e. not meeting the criteria for hypopnea), hypoventilation or oxygen desaturation20 (Figure 4.6). Controversy exists with regard to whether UARS lies on a continuum between primary (e.g. ‘benign’ snoring; snoring which is not associated with symptoms or known adverse physiologic consequences) and OSAHS, or if it is a distinct clinical syndrome.21 UARS patients have subtle airflow limitation as a
60
Diagnostic studies for sleep apnea/hypopnea
EEG Arousal Airflow
Effort (rib cage)
Effort (abdomen) Effort (Pes cm H2O)
% SaO2
0 –20 –40 –60 100 75 50
10 s
Figure 4.6 Respiratory effort-related arousal (RERA): peak increase in respiratory effort (as shown with more negative esophageal pressure) followed by arousal.
consequence of increased upper airway resistance, but not necessarily a reduction in tidal volume, due to the ‘protective’ compensatory physiologic responses, including increased inspiratory effort. This increased effort is a hallmark of UARS but may not be easily identifiable by the usual clinical monitors such as qualitative measures of chest wall (e.g. rib cage and abdomen).20 However, esophageal manometry or calibrated inductance plethysmography may reveal increasing inspiratory efforts unaccompanied by increased inspiratory flow leading to arousal. Furthermore, more quantitative recording of flow, or recording of pressure fluctuations at the nares (nasal pressure transduction), may reveal inspiratory flow limitation, which is characteristic of increased airway resistance (Figure 4.6).22
UARS patients usually but not universally have crescendo snoring prior to arousal.23 While the UARS and OSAHS are entities which reflect a constellation of physiologic and clinical conditions, individual events in which arousal results from increased inspiratory effort associated with elevated upper airway resistance (e.g. apneas, hypopneas, or elevated airway resistance even in the absence of reduced airflow or tidal volume) have been termed respiratory effort-related arousals (RERAs).24 The American Academy of Sleep Task Force7 defined RERA or UARS as a: ‘Pattern of progressively more negative esophageal pressure, terminated by a sudden change in pressure to a less negative level and an arousal with an event lasting 10 seconds or longer’ (Figure 4.6). Physiologic and clinical
Clinical predictors of OSAH
61
Table 4.1 Types of studies for evaluating sleep apnea (minimum of 6 h of overnight recording). Level 1 Standard PSG
Level 2 Comprehensive portable PSG
Level 3 Modified portable testing
Level 4 Continuous single or dual bioparameter recording
No. of parameters measured EEG EOG Chin EMG EKG/HR Airflow
*7
*7
*4
1–3
C4–A1 or C3–A2 Required Required EKG Required
C4–A1 or C3–A2 Required Required EKG or HR Required
Not measured Not measured Not measured Optional Optional
Respiratory effort
Required
Required
O2 saturation Body position
Required Visual or measured Optional In attendance
Required Measured (optional) Optional Not in attendance
Not measured Not measured Not measured EKG or HR Either one channel of each effort and airflow or two channels of effort Required Measured (optional) Optional Not in attendance
Leg movement Personnel intervention
冦
Optional
Measured Not measured Not measured Not in attendance
EOG, electro-oculogram; HR, heart rate; PSG, polysomnography; EEG, electroencephalogram; EKG, electrocardiogram.
manifestations of RERA or UARS may also be present in some non-snoring individuals, but the exact prevalence is unknown.
Clinical predictors of OSAHS The clinical features of OSAHS are described in detail in Chapter 1. Several studies have
examined the clinical predictors of OSAHS using various symptoms, signs, risk factors and morphologic parameters. The ‘Berlin Questionnaire’25 examined the presence and frequency of snoring, waketime sleepiness or fatigue, and history of obesity or hypertension, defining a group at high risk for OSAHS by the presence of at least two of these variables. The questionnaire had a sensitivity of 0.86, a specificity of 0.77, a positive predictive value of 0.89, and a likelihood ratio of 3.79 in identifying patients with AHI * 5/h.25 Flemons et al
62
Diagnostic studies for sleep apnea/hypopnea
observed that the AHI correlated linearly with neck circumference, hypertension, habitual snoring and bedpartner reports of nocturnal gasping/choking respirations.26 Employing a morphometric model, Kushida et al found a combination of values for body mass index (BMI), neck circumference and oral cavity measurements to be highly predictive of AHI * 5/h (sensitivity 97.6%, specificity 100%, positive predictive value 100%, and negative predictive value 88.5%).27
Objective diagnostic studies for sleep apnea The variables recorded during diagnostic evaluation for sleep apnea depend upon the type of recording device that is used. A Task Force established by the American Sleep Disorders Association suggested four levels of classification of recording devices for sleep apnea (Table 4.1):28 •
•
•
Level I devices: complete in-laboratory polysomnography including electroencephalogram, electro-oculogram and submental electromyogram, cardiopulmonary monitoring and limb movement monitoring. Level II devices: polysomnography with complete sleep and cardiopulmonary monitoring outside of the laboratory environment (e.g. in the home or on a patient care unit). In contrast to level I, level II studies do not involve the presence of a technologist during the recording. Level III devices: generally record only cardiopulmonary variables, including some measure of breathing effort, airflow, oxygen saturation, and either heart rate
•
(by cardiotachometer) or an electrocardiogram (ECG). Level IV devices: typically record only one to three variables, such as pulse oximetry and ECG. Some devices also provide a recording of airflow. Studies at this level provide the least information.
Polysomnography Polysomnography (PSG) refers to multichannel recording of sleep and breathing variables and, when attended by a trained technician, is the historical and ‘gold standard’ method employed to diagnose OSAHS and other sleeprelated disorders such as periodic limb movements disorder (PLMD) and rapid eye movement sleep behavior disorder. PSG has traditionally been performed overnight. However, the time and labor-intensive nature of attended, overnight PSG and the consequent cost and resource burden of these studies has led to several modifications in the way in which these studies are performed at some centers. One variation is to perform PSG during a daytime nap (nap PSG). Care must be taken when making clinical decisions based on these studies which may be unreliable for the evaluation of sleep architecture and may underestimate the severity of the sleep apnea, particularly if REM sleep or sleep in the supine position is not recorded.29 There are few systematically collected data addressing the value of nap recordings. It appears, however, that a positive study is likely to be valid but a negative study is inadequate to definitively exclude a diagnosis of sleep apnea.30,31 Daytime studies are appropriate in shiftworkers who normally sleep during the daylight hours.
Polysomnography Data collection, derived information and its importance Full PSG typically records sleep stage, breathing effort, airflow, oxyhemoglobin saturation by pulse oximetry (SpO2), an electrocardiogram (ECG), body position, and limb movements.
63
efficiency and prolonged REM latency (‘the first night effect’).42 Although this may be of concern when performing PSG to diagnose a non-pulmonary sleep–wake disorder, the clinical significance of the ‘first night effect’ and night-to-night variability in the frequency of respiratory disturbances in patients who have more than mild OSAHS is believed to be minimal.42,43
Sleep stages and arousal
Sleep stages are monitored by recording the electroencephalogram (EEG), right and left electrooculogram (EOG), and submental electromyogram (EMG). The latter two parameters identify the eye movements and postural muscle hypotonia that characterize and help define REM sleep. Sleep stage percentages and distribution can be calculated, as well as latencies to each of the various stages. In patients with intrinsic lung disease, the apneas and oxyhemoglobin desaturation, even in the absence of specific apnea and hypopnea events, are usually most marked in REM sleep.32–40 Thus, comprehensive assessment for sleepdisordered breathing requires recording during REM sleep. Apneas and hypopneas are terminated by an arousal, which can be identified as a transient (3–14-s) activation of the EEG.41 Arousals, regardless of cause, may result in sleep fragmentation and are believed to be a primary mechanism responsible for daytime hypersomnolence in patients with a variety of sleep disorders (e.g. OSAH, PLMD). Identifying the cause of arousals is essential in establishing a diagnosis and treatment planning. The frequency of arousals (arousal index) becomes an important descriptor of the sleep continuity. The first night of sleep in the unfamiliar laboratory environment may be qualitatively and quantitatively different from sleep at home or during subsequent nights in the laboratory, being characterized by decreased sleep
Monitoring of breathing Airflow changes
Distinguishing a normal breath from an apnea or hypopnea requires a measure of airflow or tidal volume. Various devices have been employed to detect oral and nasal airflow. These include pneumotachography, nasal pressure transduction, use of thermal sensors,44 rapid response carbon dioxide (CO2) analyzers, and laryngeal and tracheal microphones.45–47 The advantages and disadvantages of the various devices are shown in Table 4.2. Recently, recording fluctuation of pressure at the nares with inspiration and expiration has been reported to reflect phasic airflow and demonstrate inspiratory airflow waveform. As with a classic pneumotachograph, variation in the pattern of pressure changes at the nose reflects the pattern of airflow. In this regard, flattening of the inspiratory waveform appears to be a good marker for inspiratory flow limitation and increased upper airway resistance.48 Comparisons of a pneumotachograph recording with nasal pressure, and nasal pressure with thermistor, for the detection of sleep-disordered breathing events, are shown in Figures 4.7 and 4.8, respectively. Respiratory effort monitoring
Absence of airflow in conjunction with absent rib cage and abdominal movements (effort)
64
Diagnostic studies for sleep apnea/hypopnea
Table 4.2 Various techniques for the measurement of airflow changes. Technique
Advantages
Disadvantages
Pneumotachography: Quantitates airflow by providing breath-to-breath measurements, measured by a snug-fitting mask attached with the pneumotachometer (Figure 4.7)
Reference standard for the measurement of airflow changes7 Provides quantitative measurements of airflow and easily integrated to yield tidal volume Can be incorporated into nasal CPAP systems More sensitive than thermal sensors for detecting hypopneas48 (Figure 4.7) Moderate accuracy in measuring ventilation while awake49
Intolerance to mask–pneumotachograph system, especially in minimally sleepy patients Cumbersome to use and may alter sleep architecture
Nasal pressure: Pressure fluctuation at nose during inspiration and expiration reflects indirect measurement of inspiratory and expiratory airflow. Used either with a full-face mask or nasal pressure cannulae connected to a sensitive pressure transducer (Figures 4.7 and 4.8) Thermal sensors (oronasal thermistor or thermocouples): Senses alteration in heat exchange during inspiration and expiration providing indirect measurement of airflow changes44 (Figure 4.8)
Simple and easy to use Well tolerated Less expensive
Expired CO2: Provides indirect measurement of airflow by detecting increased CO2 in expired air
Easy to use Qualitative or semi quantitative indicator of airflow
Tracheal sound: Airflow through trachea produces sound audible via microphone
Qualitative measurement of airflow Inexpensive and easy to use Can be use to quantitate snoring
Less sensitive than pneumotachometer for detecting hypopneas50 Not clear whether sensitivity for the detection of hypopnea would improve if criteria for oxygen desaturation or an arousal were included7 If only nasal pressure cannulae are used, the technique may lack sensitivity if the patient employs predominantly mouth breathing Appears promising, but not recommended as a measurement of a RERA7 Less sensitive than pneumotachometer and nasal pressure48,51 (Figure 4.7) Poor accuracy in recording hypopneas in awake subjects under ideal conditions49 Provides only qualitative information about airflow changes Limited data about the accuracy and precision of these devices Signal quality reduced during nasal CPAP treatment Significant time delay because air is sampled continuously for remote analysis Signal quality reduced during nasal CPAP treatment No data on the accuracy for detecting hypopneas and its correlation with outcomes No data to evaluate the accuracy and precision of expired CO2 Sound amplitude also increases during snoring or partial airflow obstruction No data to evaluate its usefulness and accuracy
CPAP, continuous positive airway pressure; RERA, respiration effort-related arousal.
Polysomnography
65
1.5
Expiration
0.0
Inspiration
Pneumotachograph Nasal prongs (NP) Square root of NP
–1.5 0
10
20
30
40
50
60
Time (s)
Figure 4.7 Comparison between pneumotachograph and nasal prongs: nasal flow recorded simultaneously with a pneumotachograph (solid line) and nasal prongs (dashed line). The dotted line represents the square root of the prongs signal. For comparison, the amplitude of the nasal prongs signal and of its square root were scaled to achieve the same amplitude as with the pneumotachograph in the first breathing cycle. Note that the signal from the nasal prongs overestimates the pneumotachograph signal, and that after the square root correction, the nasal prongs signal was almost coincident with the pneumotachograph signal.48
implies central apnea, whereas the absence of airflow despite persistent chest wall movement with or without paradoxical motion of rib cage and abdomen identifies an obstructive apnea. Respiratory effort can be assessed by quantitative or qualitative respiratory inductance plethysmography (RIP)52 or by qualitative measures including impedance pneumography,53 piezo sensors or strain gauges (Table 4.3). However, the ‘gold
standard’ to quantify inspiratory effort is recording breath-by-breath esophageal pressure fluctuations reflecting swings in intrathoracic pressure using an esophageal balloon/pressure catheter (Table 4.3). Thus, several options exist for monitoring breathing effort. There are, however, few studies addressing the relative efficacy of each in the clinical environment. In view of its noninvasive nature and ease of use, qualitative RIP
66
Diagnostic studies for sleep apnea/hypopnea
EEG EOG EOG EMG
Legs Thermistor Rib Abdomen Nasal cannula SaO2
Figure 4.8 A 120-s section from PSG in one subject with hypopnea that is easily detected on the nasal cannula signal (nasal pressure) but missed by the thermistor. Chest wall and abdominal movements were monitored with piezoelectric strain gauges.
(uncalibrated) is often employed and is generally a reliable clinical tool, although the clinician must recognize the limitations (see Table 4.3). Qualitative RIP may misclassify obstructive apneas as central apneas. If clinically indicated, the clinician should consider repeating PSG using an esophageal catheter in patients in whom qualitative RIP has been employed and in whom only central apnea was identified, in order to confirm this diagnosis. Making the distinction between central and obstructive apnea is important, since the subsequent evaluations and treatment strategies may differ.62
Although there is a wide variety of techniques for measurement of respiratory airflow and effort, there are, at present, insufficient data to develop firm and universal recommendations about which instrumentation is optimal. The situations in which measurements of esophageal pressure should be used as the preferred method quantitatively to assess respiratory effort are uncertain. Additional studies are needed to examine the error rates in identification and typing of respiratory events with different currently employed methodologies. The American Academy of Sleep Medicine Task Force7 has
Polysomnography
67
Table 4.3 Various techniques for the measurement of respiratory efforts. Technique
Advantages
Disadvantages
Esophageal balloon or pressure catheter
Reference standard for measuring respiratory effort7 Reference standard for the detection of central apnea or hypopnea7 Reference standard for the detection of RERA or UARS7 Sleep profile does not appear to be significantly affected in patients with OSAHS54 Provides semiquantitative measurement of ventilation, but most sleep laboratories use uncalibrated RIP (qualitative) Can also provide indirect measurement of airflow (tidal volume is proportional to airflow) Inexpensive Easy to use
Invasive Not universally tolerated May interfere with sleep by reducing total sleep time and sleep efficiency in non-apneic patients54 No studies have compared alternative techniques of measuring respiratory effort or flow limitation with the reference standard Relatively expensive
Respiratory inductance plethysmography (RIP): Detects changes in the circumference of the rib cage and abdomen during breathing; when properly calibrated, the sum of these two signals provides a measure of tidal volume Piezo sensors, strain gauges, and thoracic impedance
Cumbersome nature of the calibration technique and controversy regarding the optimal calibration method55,56 Frequency of central apnea may be overestimated57 Unclear whether it provides quantitative measurements of ventilation throughout sleep period in unrestrained humans who often changes body position58–60 Less reliable than the RIP More sensitive to the changes in body position that may produce reduction in transducer tension61 Few data on which to judge the accuracy of these sensors to qualitatively or semiquantitatively record flow or volume changes compared with reference standards
RERA, respiratory effort-related arousal; UARS, upper airway resistance syndrome; OSAHS, obstructive sleep apneahypopnea syndrome.
recommended reference standard methods as well as other comparative but less sensitive methods for the detection of airflow and respiratory changes as shown in Table 4.2 and 4.3.
The quality of evidence and recommendation grades for various breathing monitoring devices in the detection of sleep-disordered breathing events are described in an original
Diagnostic studies for sleep apnea/hypopnea
Oxyhemoglobin saturation
Monitoring oxyhemoglobin saturation provides the clinician with a parameter of sleep disorder severity and consequently may be useful in management decision-making. Pulse oximeters have proven to be a major asset in the diagnosis and severity assessment of sleep-disordered breathing. It is noninvasive, relatively unobtrusive and, within limitations, discussed below, accurate.63 The clinician should be aware, however, that variation in the oximeter response sampling and response frequency may influence the accuracy in measurements of the oscillatory changes in oxyhemoglobin saturation that are typical of patients with sleep-disordered breathing. Optimal detection of fluctuations in oxyhemoglobin saturation requires that the signal averaging time should not exceed 3 s. A longer averaging time risks underestimation of the severity of the magnitude of desaturation, as shown in Figure 4.9.64 The response time may also vary with the characteristics or the placement of pulse oximeter probes (e.g. the finger or the ear). Clinicians should evaluate both the steady-state and transient responses of oximeters before employing them for cardiopulmonary sleep studies. There is a need to develop standards for such instrumentation in a similar fashion to the standards developed for spirometry.65 The clinician should be aware that pulse oximetry readings may be inaccurate in certain clinical situations, even if the device is functioning properly and is free from the external interference. Abnormal hemoglobin or hemoglobin variants may interfere with the accuracy of pulse oximetry if absorption properties are similar to those of ‘normal’
100 SaO2 (%)
paper by the American Academy of Sleep Medicine Task Force.7
90 80 70
100 SaO2 (%)
68
90 80 70 0
60
120
180
240
Time (s)
Figure 4.9 Example of the SaO2 signals measured with two identical pulse oximeters simultaneously. Top: one oximeter was set to an averaging time (T) of 3 s (control). Bottom: the other oximeter was first set to T = 3 s and subsequently to T = 21 s. The vertical dashed line indicates the time when the setting of T was moved from 3 s to 21 s.
oxyhemoglobin or deoxyhemoglobin. For example since carboxyhemoglobin absorbs approximately the same amount of light as oxyhemoglobin, a pulse oximetry value may not represent oxyhemoglobin (Figure 4.10).66–70 In cases of carbon monoxide poisoning or in chronic, heavy smokers, a falsely reassuring pulse oximetry reading may notably mask reduced oxyhemoglobin saturation. Methemoglobin also absorbs a similar amount of light as oxyhemoglobin,68 and SpO2 tends to be about 85% at higher methemoglobin levels, regardless of the true percentage of oxyhemoglobin (Figure 4.11).66,71–73 When
Polysomnography 100
100 SpO2 80
90
60
80
SpO2 and SaO2 (%)
Saturation SpO2 or O2Hb (%)
69
40 O2Hb
20 FiO2 = 1.0 0 0
20
40
60
80
100
70 60 50
COHb 40
Figure 4.10 Effect of carboxyhemoglobin on measured oxygen saturation by pulse oximetry (SpO2). SpO2 and O2Hb versus carboxyhemoglobin (COHb) at FiO2 = 1.0. SpO2 consistently overestimates saturation in the presence of COHb. At 70% COHb and 30% O2Hb, SpO2 is still around 90%. (Adapted from Barker and Tremper.)69
carboxyhemoglobinemia or methemoglobinemia is suspected, co-oximetry, rather than pulse oximetry is required to accurately measure oxyhemoglobin. Co-oximeters use four rather than two wavelengths of light to detect oxyhemoglobin, deoxyhemoglobin, carboxyhemoglobin, and methemoglobin, but require a sample of arterial blood.74,75 Sickle cell and fetal hemoglobin generally produces pulse oximeter readings similar to those of normal hemoglobin.76–78 Several methods have been proposed to describe a patient’s oxyhemoglobin saturation during sleep. Perhaps the most frequently used is the nadir of O2 saturation, but this value
FiO2 = 1.0
30 0
20
40
60
MetHb (%)
Figure 4.11 Effect of methemoglobin on measured oxygen saturation by pulse oximetry. SpO2 reading (blue circles) and true SaO2 by blood gas (red square along the line) versus MetHb percentage at FiO2 = 1.0. (Adapted from Barker et al.)72
may not be the most physiologically relevant, because it may relate to a single, transient event. Other measures, such as mean overnight oxyhemoglobin saturation or average desaturation per event, have also been used. A convenient graphical format is the cumulative oxyhemoglobin saturation histogram, in which the total percentage of sleep time spent at each saturation is presented.79 From this format, a number of descriptive parameters may be derived, including percentage of time spent with SpO2 below 90%, 80%, 70% and 60% and the SpO2 at which 50% of the time is spent. Unfortunately, we do not currently know the degree and
70
Diagnostic studies for sleep apnea/hypopnea
duration of desaturation that reflects a health hazard. Apneas and hypopneas often result in oxyhemoglobin desaturation, usually reaching nadir levels within 30 s of the termination of the abnormal breathing event. Oxyhemoglobin saturation monitoring may show recurrent episodes of desaturation and resaturation in a ‘saw-tooth’ pattern in patients with OSAHS. As discussed above the oximeter should be set to the fastest response speed in order to accurately capture the transient peaks and troughs of SpO2. Limb movements
Limb movements are recorded during PSG using a surface EMG of the anterior tibialis muscle. It is important to detect these movements, because they may define PLMD, a primary sleep disorder in which repetitive leg movements or ‘jerks’ precipitate arousals, resulting in daytime sleepiness. It is not infrequent that patients have more than one sleep abnormality. PLMD may be either a comorbid feature of sleep-disordered breathing, or a consequence of OSAH (e.g. arousals due to abnormal breathing events resulting in secondary limb movement). It is important to distinguish primary from secondary limb movements, because of their impact on therapeutic directions. As with other variables, one can calculate the number of limb movement events per hour of sleep and identify those that occur independently from abnormal breathing events in order to define and potentially quantify disease severity (i.e. PLMD). Snoring
The amount and intensity of snoring may be determined with a microphone placed over the upper airway. Snoring can be used as an
additional marker to titrate therapy with positive pressure,80 although inspiratory airflow limitation is a more useful and sensitive marker than snoring alone.81 There is, however, no standardized, commercially available device to calibrate these microphones for clinical use. Body position monitoring
The severity of OSAHS may vary with body position (generally worse in the supine position) and, since this feature may have therapeutic implications, it is important to monitor posture during sleep. Furthermore, recording sleep and breathing in all body positions increases the comprehensive degree of the PSG and may enhance the predictive power of the results. Body position monitors can provide information regarding body position dependency of sleep-disordered breathing.82 Some patients with such supine position dependency may be treated using the ‘sleep-sock’ technique, wherein a tennis ball is placed in a sock which is safety-pinned to the back of the sleeping garment. If the patient assumes the supine position, he or she will be prompted to resume sleeping in lateral recumbency. It should be noted that the long-term effectiveness of this intervention has not been systematically evaluated in large study populations. Electrocardiogram
The ECG is useful to detect arrhythmias or variability in heart rate associated with sleepdisordered breathing.83,84 Identification of dysrhythmias and arrhythmias may affect therapeutic strategies, which may be more or less aggressive depending on the nature of the ECG abnormality (e.g. as it indicates cardiac ischemia or rhythm abnormalities). Moreover,
Polysomnography heart rate acceleration may be a clue to arousal.
Validity of diagnostic polysomnography PSG is considered the ‘gold standard’ for the diagnosis of sleep disorders. However, a negative PSG does not conclusively exclude the diagnosis of OSAHS, especially in adults with a high pretest clinical suspicion of the disease. One prospective study demonstrated that a single negative study was inadequate to exclude OSAHS in patients with one or more of the important clinical markers of the disease, and 6 of 11 such patients had a positive second sleep study. Thus, a second diagnostic PSG should be considered in patients who have an unexpectedly negative first study.
71
or treatment efficacy. Newly developed selfadjusting CPAP machines that monitor inspiratory flow may be as effective as sleep technicians in determining the CPAP prescription for home use85 but trained technologists remain a valuable problem-solving and educational resource during the titration process. An apparent value of auto-titrating CPAP devices is to eliminate the burden of manual titration on technicians, thereby permitting greater freedom to provide patient education and support, which hopefully will increase adherence to recommended therapy.86 A more complete discussion of positive-pressure therapy is provided in Chapter 6. PSG can also be used for a follow-up evaluation to determine the adequacy of treatment, the timing of which depends on the nature of the treatment (weight loss, medication, positive-pressure therapy, surgery, oral appliances, assisted ventilation, etc.).
‘Split-night’ PSG studies Assessment of treatment modalities Besides its utility as a diagnostic tool, PSG has been used in the context of titrating continuous positive airway pressure (CPAP) or bilevel positive pressure therapy for OSAHS. During PSG, pressure applied via nasal mask, full facemask or nasal prongs is increased in response to persistent snoring, apneas, hypopneas, desaturations, or arousals. The optimal pressure determined from this type of evaluation is used for the prescription of home therapy. Laboratory PSG (level I) during titration identifies persistent arousals that are not attributable to OSAHS but may be caused by PLMs, and also identifies leaks at the interface or mouth that might impair patient tolerance
Traditionally, patients undergo a diagnostic PSG over a full night in the sleep laboratory, with a subsequent night of study during which positive-pressure titration is performed. However, there has been a recent trend to perform split-night studies, in which the diagnosis of OSAHS is established in the first portion of the night of PSG monitoring and the therapeutic positive pressure and optimal interface are determined during the second portion of the night. The diagnostic portion of the study generally reflects a period of 2–3 h. If moderate to severe OSAHS is diagnosed, the remaining 3–5 h of the study are available for titration. When positive for OSAHS, the first half of the night has been shown to provide a reasonably accurate appraisal of disease severity,87,88 and a single split-night study can also
72
Diagnostic studies for sleep apnea/hypopnea
establish the correct pressure in a majority of patients.88–91 Patient adherence does not appear to be adversely affected by a half night versus a full night of titration in the laboratory.91–93 This method appears to be a realistic approach to diagnosis and the initiation of therapy, particularly in patients with high pretest clinical probability and enough events (usually more than 30 apneic events) recorded for the diagnostic portion of the split-night study. A partial night diagnostic study that is negative for OSAHS cannot reliably exclude the diagnosis, and therefore recording must be continued for a full night in these instances. MSLT should not be performed after a splitnight study, since the patient will not be in a ‘steady state’ during this time.
Evaluation of sleepiness Hypersomnolent patients may complain of excessive daytime sleepiness (EDS), falling asleep in inappropriate places and under inappropriate circumstances (e.g. while driving, at school, at work, during social activities). The consequences of EDS can be severe, including motor vehicle accidents, workrelated accidents/injuries or household accidents. EDS can be evaluated subjectively by the Epworth Sleepiness Scale (ESS) and objectively by either multiple sleep latency test (MSLT) or maintenance of wakefulness test (MWT). Demonstration of EDS is not required for the diagnosis of OSAHS, so, objective evaluation (MSLT or MWT) is not mandatory in the evaluation of OSAHS. However, if a PSG does not reveal a specific diagnosis, MSLT performed on the subsequent day may provide useful information regarding the presence of a different sleep disorder such as narcolepsy. Similarly, when complaints of sleepiness persist
after adequate treatment for OSAHS is instituted, an MSLT may reveal another sleep disorder requiring a separate treatment approach. The details of the subjective (ESS) and objective (MSLT or MWT) measurement of EDS are discussed in Chapter 2.
Screening and ambulatory monitoring techniques A number of ‘simplified’ approaches have been suggested for screening for or diagnosing individuals with sleep-disordered breathing, but there are few validatory data regarding the cost-effectiveness of all these various screening techniques in the evaluation of sleep-disordered breathing. A study by Chervin et al94 comparing cost-effectiveness of PSG, home study and no testing showed superior costutility of PSG over a period of 5 years since the initial evaluation for sleep apnea, compared to home study or no diagnostic testing. Screening devices include four-channel cardiopulmonary monitoring (level III) and pulse oximetry (level IV). Other less commonly used techniques include tracheal sound recordings,45–47 exhaled CO2 detector to monitor airflow to identify apnea,95 and the static charge-sensitive bed.96,97 With the method of static charge-sensitive bed, a mattress on which the patient sleeps sends signals that relate to the heartbeat (ballistocardiography), breathing movements, and body movements. When combined with oximetry, the static charge-sensitive bed technique may have some utility in detecting apneas, although validation of this device remains at the preliminary stage97 and use in North America appears to be very limited indeed.
Screening and ambulatory monitoring techniques Heart rate (beats/min)
73
200 100 75 50 25
Impedance
Thermistor A
SaO22 (percentage) SaO percentage
A
A
100 90 80 70 60 50
Figure 4.12 Typical tracing from a four-channel cardiopulmonary recording. The parameters measured include pulse rate, chest wall impedance, airflow, and oxygen saturation. Obstructive apneas are denoted by the letter A.
Level III devices A 1994 position paper by the American Sleep Disorders Association suggested that level III and IV studies should be restricted to urgent circumstances.98 However, several subsequent studies have suggested that, within limitations, these devices are reliable and potentially useful in the diagnosis and management of OSAHS.99,100 Each of these techniques has particular strengths and weaknesses, and it is
probably optimal to have all the devices available in a large sleep disorders center. A recording from a typical level III device is shown in Figure 4.12. In this example, breathing effort is detected by chest wall impedance monitors, airflow at the nose and mouth by a temperature-sensitive thermistor, and changes in oxyhemoglobin saturation and heart rate by pulse oximetry. The frequency of apneas and hypopneas may be assessed with these devices, although it may be difficult to classify these as
74
Diagnostic studies for sleep apnea/hypopnea
central or obstructive with certainty. Level III devices do not record sleep, and therefore arousals cannot be identified. These devices have the greatest utility when there is a high clinical, pretest probability of OSAHS with a low clinical likelihood of a significant falsenegative study. Portable recording devices may be used to diagnose OSAHS in the home as well as in sick, hospitalized patients who are too ill to be evaluated in an outpatient laboratory setting. Although it remains to be tested, home recording may also be more convenient and less costly than laboratory studies to assess the adequacy of existing treatment for OSAHS with positive airway pressure, weight loss, surgery, or an oral appliance, although this is unproven. It is controversial whether nasal CPAP can be accurately titrated to the patient’s therapeutic needs using home monitoring. Most sleep specialists believe that the most accurate pressure recommendations can be made after assessment through full PSG, although titration utilizing a fourchannel, level III portable recorder in the home environment has been reported.101 In this study, however, a technologist was present at the bedside to adjust the pressure when appropriate, in response to breakthrough events. The new technological development of auto-adjusting nasal CPAP units may resolve this issue in the future. Studies comparing technician-determined optimal CPAPs and pressures determined by an auto-titrating machine in patients with sleep apnea found no difference between the manually derived pressure determined with full PSG monitoring and the pressure derived by the auto-adjusting device in sleep laboratory or in home settings.85,102 Level III devices have some notable limitations. Interpretation must be performed in the absence of objective measures of sleep. It is
essential that the clinician assess the results of any level III device study in the context of the pretest clinical suspicion for the presence of sleep apnea.103 There also remains a paucity of evidence-based literature supporting the validity of level III devices in the diagnosis of sleepdisordered breathing in otherwise unselected patients (e.g. without excluding individuals with underlying pulmonary or neurologic disorders such as might be seen in the patient population referred to sleep centers).
Level IV devices Application of pulse oximetry alone as an example of a level IV device in the diagnosis of OSAHS is controversial. Although OSAHS can produce a classic oximetry pattern of desaturation–resaturation, there is inadequate sensitivity for routine diagnostic use.28 The sensitivity of oximetry may be increased when combined with a pretest clinical score, but it has been suggested that some patients may still be missed28 due to the relatively low predictive value for the detection of apnea (0.56).104 To determine the accuracy of oximetry alone for diagnosing sleep apnea, Douglas and colleagues105 studied 200 patients with PSG and oximetry. They found 53% sensitivity and 97% specificity for diagnosing sleep-disordered breathing, using event identification criteria of * 4% desaturation/event and >10 events/h.105 In cases where the clinical suspicion is not high, an oximetry study may be adequate to exclude significant OSAHS from consideration, if the criterion for a positive study is the identification of 10 rapid, shortduration desaturations per hour.63,106 Home overnight oximetry is frequently used to assess the efficacy of OSAHS therapy, but investigations employing long-term outcome measures have not been published. Clinicians
Radiographic imaging must be cognizant of the very limited nature of the information provided by this modality, which provides no data relating to sleep continuity. Furthermore, the possibility of sleepdisordered breathing events unaccompanied by oxyhemoglobin desaturation but nonetheless associated with sleep fragmentation cannot be excluded by oximetry. If home oximetry study shows normal SpO2 while the patient is on therapy, and previous sleep apnea symptoms have resolved, then the physician and patient may be somewhat reassured that the therapy is adequate. In this regard, the definition of adequate overnight oxyhemoglobin saturation remains open to question. Finally, a single night of oximetry may not be representative of the patient’s actual response to therapy, and it is unclear if such studies are useful and cost-effective. The value and optimal use of oximetry in the evaluation of patients suspected of having sleep-disordered breathing are not known with certainty.106 Practice parameter guidelines published by the American Sleep Disorders Association in 1994 recommended that level IV devices should not be used for the evaluation of OSAHS.98
Radiographic imaging Although there are no evidence-based data, radiographic imaging may be an adjunct to clinical evaluation, particularly when surgical treatment or dental appliances are considered as treatment options. It has significantly advanced our understanding of the pathogenesis of sleep apnea, and it may also identify various sites of upper airway obstruction to potentially facilitate individualization of treatment strategies. The role of upper airway imaging in the evaluation and management of sleep-disordered breathing seems promising,
75
but there is a paucity of evidence-based literature supporting these techniques, and therefore any discussion in this regard is conceptual. There does not appear to be an evidence-based role for routine use of sophisticated imaging techniques in the evaluation of patients with suspected OSAHS. The upper airway can be subdivided anatomically into three regions:107–109 (1) The nasopharynx (the region between the nasal turbinates and the hard palate); (2) The oropharynx, which can be subdivided into the retropalatal region (also called the velopharynx) and the retroglossal region, and; (3) the hypopharynx (the region from the base of the tongue to the larynx). Imaging techniques have revealed that the upper airway is smallest in the oropharynx in both normal subjects and patients with OSAHS, particularly in the retropalatal region.107,110–113 Airway closure during sleep occurs in the retropalatal region in the majority of patients with sleep apnea.114,115 The relevant anatomic structures of this region (tongue, lateral pharyngeal walls, lateral parapharyngeal fat pads) in normal patients and in patients with OSAHS are shown in Figures 4.13 and 4.14. The ideal upper airway imaging modality in OSAHS is one which is inexpensive and noninvasive, and does not involve radiation. In addition, it should be performed in the supine position, with the possibility of dynamic imaging during sleep in order to visualize apneic events, and should provide high-resolution anatomic representations of the airway and soft tissue structures. Such an ideal modality does not exist; the advantages/usefulness and disadvantages/limitations of various techniques are summarized in Table 4.4. Upper airway imaging is not indicated in the routine clinical evaluation, as its value in diagnosing and developing management strategies for OSAHS has not been established.
76 A
Diagnostic studies for sleep apnea/hypopnea B
Figure 4.13 Reduced upper airway size in obstructive sleep apnea: comparison of a mid-sagittal image of a normal subject (A) and a patient with sleep apnea (B). Soft palate and tongue area are larger in the patient with sleep apnea, leading to a reduction in upper airway size. (RP, retropalatal region, from the level of the hard palate to the distal margin of the soft palate; RG, retroglossal region, from the distal margin of the soft palate to the base of the epiglottis).
A
B Figure 4.14 Reduced airway size in obstructive sleep apnea: comparison of an axial image at the minimum airway area (retropalatal region) of a normal subject (A) and a patient with sleep apnea (B). Note the smaller airway size and airway width in the patient with sleep apnea. In addition, the thickness of the lateral pharyngeal wall (distance between the airway and parapharyngeal fat pads) is greater in the patient with sleep apnea.
Radiographic imaging
77
Table 4.4 Advantages and disadvantages of various imaging modalities. Technique
Advantages
Disadvantages
Cephalometry: Lateral radiograph of the head and neck
Widely available and easy to perform No weight limitation Less expensive than CT or MRI Evaluates bony abnormalities such as retrognathia Useful in the evaluation of patients undergoing maxillomandibular advancement or placement of dental appliances Useful in predicting palatopharyngoplasty failure116
Fluoroscopy
Dynamic upper airway imaging during wakefulness or, potentially, during sleep
Acoustic reflection: Measurement of airway caliber on the basis of reflected sound waves
Non-invasive No associated radiation Reproducible Possibility of dynamic imaging No weight limitation New devices may permit assessment during sleep
Radiographic equipment; technique and interpretative skills must be standardized Performed only in the sitting or standing position while patients is awake, and may not reflect condition during sleep Two-dimensional evaluation of skeletal and soft tissue structures, no volumetric analytic capabilities Limited information about anterior–posterior structures and no information about lateral soft tissue structures Significant radiation exposure Insensitive to measure changes in airway size or the detailed motion of the soft tissue structures surrounding the upper airway No capability of cross-sectional (axial or sagittal) imaging Performed while the patient is awake, and may not reflect condition during sleep Primarily used as a research tool; clinical usefulness has not been adequately studied Performed while patient is awake, in the sitting position, through the mouth, which alters upper airway anatomy Does not provide high-resolution anatomic representation of the airway or soft tissue structures Invasive Evaluates only airway lumen, not surrounding soft tissue structures Generally performed during wakefulness; cumbersome to do during sleep
Nasopharyngoscopy Widely available and easy to perform No radiation, no weight limitation Can be performed in sitting or supine positions during wakefulness or sleep Muller maneuver, performed during the procedure, may provide insight into the location of upper airway closure by potentially simulating obstructive apneas
continued
78
Diagnostic studies for sleep apnea/hypopnea
Table 4.4 continued Advantages and disadvantages of various imaging modalities. Technique
Computed tomography
MR imaging
Advantages May be useful in predicting UPPP outcome by determining if retropalatal or retroglossal obstruction occurs during the Muller maneuver117–119 May be useful to identify upper airway lesions (e.g. tumors) Supine imaging Accurate assessment of upper airway cross-sectional area and volume Excellent airway and bony resolution; however, images acquired only in axial plane Three-dimensional reconstruction of craniofacial structures (cranium, mandible, hyoid) and airway May be useful in evaluating patients who undergo bony manipulations (dental appliances and maxillomandibular advancement) Dynamic imaging can be performed with electron beam (ultrafast CT), providing excellent temporal and spatial resolution (images in 50 ms) Helical CT allows for direct acquisition of three-dimensional images Supine imaging, generally during wakefulness Accurate assessment of upper airway cross-sectional area and volume Excellent airway, soft tissue and fat resolution Direct sagittal, coronal and axial images without radiation, so studies can be performed and repeated during wakefulness and sleep Three-dimensional reconstruction of soft tissue structures (tongue, soft palate, lateral parapharyngeal fat pads, lateral pharyngeal walls) and airway (Figures 4.13 and 4.14)
Disadvantages
Relatively expensive Weight limitation of approximately 400 lb Radiation exposure limits ability to perform repeat studies during wakefulness and sleep Poor resolution for upper airway adipose tissue compared with MRI Generally performed during wakefulness and may not reflect condition during sleep
Technique not widely available Expensive Weight limitation of approximately 300 lb Claustrophobia is a problem Cannot be performed in patients with ferromagnetic clips or pacemakers Generally performed during wakefulness and may not reflect condition during sleep
continued
Summary
79
Table 4.4 continued Advantages and disadvantages of various imaging modalities. Technique
Disadvantages
Advantages Useful in the evaluation of patients who undergo surgical procedures that alter upper airway soft tissue configuration (e.g. UPPP, geniohyoid advancement) Dynamic imaging possible with ultrafast MRI Potential for soft tissue characterization with spectroscopic imaging studies (e.g. for fat and water) and for magnetic tagging imaging to study the biomechanics for the upper airway
UPPP, uvulopalatopharyngoplasty.
There are no published studies indicating that upper airway imaging improves treatment outcome, and, in addition, those studies examining the pathogenesis of sleep apnea have largely been applied to awake patients, and may not provide an optimal representation of upper airway features and behavior during sleep.
Summary There are several diagnostic techniques and various instruments available for the evaluation of sleep-disordered breathing. The initial evaluation is based on clinical suspicion, possibly incorporating various models, examining particular clinical features, risk factors and morphometric or anthropometric measurements.
PSG is the ‘gold standard’ test for the evaluation of OSAHS, and the clinician must have knowledge of the individual monitored variables and recording as well as the limitations of the currently employed criteria employed in the scoring of abnormal events. In general, patients with high probability of OSAH based on clinical suspicion and predictability models may be candidates for split-night PSG, while the diagnostic approach in patients with low to moderate probability of OSAHS or possible other pulmonary or non-pulmonary sleep–wake disorder requires full-night PSG. Portable monitoring devices also have some use in specific situations, but with clear limitations. Radiographic imaging has potential usefulness in understanding the pathogenesis of sleep-disordered breathing, but its routine use in the evaluation of OSAHS awaits outcome data.
80
Diagnostic studies for sleep apnea/hypopnea
References 1. Pack AI. Obstructive sleep apnea. Adv Intern Med 1994;39:517–67. 2. Young T, Palta M, Dempsey J, Skatrud J, Weber S, Badr S. The occurrence of sleepdisordered breathing among middle-aged adults. N Engl J Med 1993;328(17):1230–5. 3. Redline S, Sanders M. Hypopnea, a floating metric: implications for prevalence, morbidity estimates, and case finding. Sleep 1997;20(12):1209–17. 4. Catterall JR, Calverley PM, Shapiro CM, Flenley DC, Douglas NJ. Breathing and oxygenation during sleep are similar in normal men and normal women. Am Rev Respir Dis 1985;132(1):86–8. 5. Bradley TD, Brown IG, Zamel N, Phillipson EA, Hoffstein V. Differences in pharyngeal properties between snorers with predominantly central sleep apnea and those without sleep apnea. Am Rev Respir Dis 1987;135(2):387–91. 6. West P, Kryger MH. Continuous monitoring of respiratory variables during sleep by microcomputer. Methods Inf Med 1983;22(4):198–203. 7. Report of an American Academy of Sleep Medicine Task Force. Sleep-related breathing disorders in adults: recommendations for syndrome definition and measurement techniques in clinical research. Sleep 1999;22:667–89. 8. Gould GA, Whyte KF, Rhind GB, et al. The sleep hypopnea syndrone. Am Rev Respir Dis 1988;137(4):895–8. 9. Block AJ, Boysen PG, Wynne JW, Hunt LA. Sleep apnea, hypopnea and oxygen desaturation in normal subjects. A strong male predominance. N Engl J Med 1979;300(10):513–17. 10. Martin SE, Engleman HM, Kingshott RN, Douglas NJ. Microarousals in patients with sleep apnoea/hypopnoea syndrome. J Sleep Res 1997;6(4):276–80.
11. Young T, Finn L, Hla KM, Morgan B, Palta M. Snoring as part of a dose-response relationship between sleep-disordered breathing and blood pressure. Sleep 1996;19(10 Suppl):S202–5. 12. Young T, Peppard P, Palta M, et al. Population-based study of sleep-disordered breathing as a risk factor for hypertension. Arch Intern Med 1997;157(15):1746–52. 13. Young T, Blustein J, Finn L, Palta M. Sleepdisordered breathing and motor vehicle accidents in a population-based sample of employed adults. Sleep 1997;20(8):608–13. 14. Redline S, Adams N, Strauss ME, Roebuck T, Winters M, Rosenberg C. Improvement of mild sleep-disordered breathing with CPAP compared with conservative therapy. Am J Respir Crit Care Med 1998;157(3 Pt 1):858–65. 15. Engleman HM, Martin SE, Deary IJ, Douglas NJ. Effect of CPAP therapy on daytime function in patients with mild sleep apnoea/hypopnoea syndrome. Thorax 1997;52(2):114–9. 16. Engleman HM, Kingshott RN, Wraith PK, Mackay TW, Deary IJ, Douglas NJ. Randomized placebo-controlled crossover trial of continuous positive airway pressure for mild sleep apnea/hypopnea syndrome. Am J Respir Crit Care Med 1999;159(2):461–7. 17. Marcus CL, Omlin KJ, Basinki DJ, et al. Normal polysomnographic values for children and adolescents. Am Rev Respir Dis 1992;146(5 Pt 1):1235–9. 18. Gaultier C. Sleep-related breathing disorders. 6. Obstructive sleep apnoea syndrome in infants and children: established facts and unsettled issues. Thorax 1995;50(11):1204–10. 19. Marcus CL, Keens TG, Ward SL. Comparison of nap and overnight polysomnography in children. Pediatr Pulmonol 1992;13(1):16–21. 20. Guilleminault C, Stoohs R, Clerk A, Cetel M, Maistros P. A cause of excessive daytime sleepiness. The upper airway resistance syndrome. Chest 1993;104(3):781–7.
References 21. Guilleminault C, Chowdhuri S. Upper airway resistance syndrome is a distinct syndrome. Am J Respir Crit Care Med 2000;161(5):1412–13. 22. Condos R, Norman RG, Krishnasamy I, Peduzzi N, Goldring RM, Rapoport DM. Flow limitation as a noninvasive assessment of residual upper-airway resistance during continuous positive airway pressure therapy of obstructive sleep apnea. Am J Respir Crit Care Med 1994;150(2):475–80. 23. Shepard J, Kaplan J, Parish J, et al. Snoring and sleep disordered breathing. In: Shepherd JW, ed. Atlas of Sleep Medicine. Mount Kisco, NY: Futura Pub. Co., 1991, p. 81. 24. American Academy of Sleep Medicine. Sleep-related breathing disorders in adults: Recommendations for syndrome definition and measurement techniques in clinical research. Sleep 1999;22:667. 25. Netzer NC, Stoohs RA, Netzer CM, Clark K, Stohl KP. Using the Berlin Questionnaire to identify patients at risk for the sleep apnea syndrome. Arch Intern Med 1999;131(7):485–91. 26. Flemons WW, Whitelaw WA, Brant R, Remmers JE. Likelihood ratios for a sleep apnea clinical prediction rule. Am J Respir Crit Care Med 1994;150(5 Pt 1):1279–85. 27. Kushida CA, Efron B, Guilleminault C. A predictive morphometric model for the obstructive sleep apnea syndrome. Ann Inter Med 1997;127(8 Pt 1):581–7. 28. Ferber R, Millman R, Coppola M, et al. Portable recording in the assessment of obstructive sleep apnea. ASDA standards of practice. Sleep 1994;17(4):378–92. 29. Series F, Cormier Y, La Forge J. Validity of diurnal sleep recording in the diagnosis of sleep apnea syndrome. Am Rev Respir Dis 1991;143(5 Pt 1):947–9. 30. Silvestri R, Guilleminault C, Coleman R, et al. Nocturnal sleep versus daytime nap findings in patients with breathing abnormalities during sleep (abstract). Sleep Res 1982;11:174.
81
31. Roberts CJ, Hooper RG. Prediction of polysomnography results by abbreviated testing (abstract). Chest 1985;88:4435. 32. Findley LJ, Wilhoit SC, Suratt PM. Apnea duration and hypoxemia during REM sleep in patients with obstructive sleep apnea. Chest 1985;87(4):432–6. 33. Coccagna G, Lugaresi E. Arterial blood gases and pulmonary and systemic arterial pressure during sleep in chronic obstructive pulmonary disease. Sleep 1978;1(2):117–24. 34. Wynne JW, Block AJ, Hemenway J, Hunt LA, Flick MR. Disordered breathing and oxygen desaturation during sleep in patients with chronic obstructive lung disease (COLD). Am J Med 1979;66(4):573–9. 35. Douglas NJ, Calverley PM, Leggett RJ, Brash HM, Flenley DC, Brezinoa V. Transient hypoxaemia during sleep in chronic bronchitis and emphysema. Lancet 1979;i(8106):1–4. 36. Fletcher EC, Gray BA, Levin DC. Nonapneic mechanisms of arterial oxygen desaturation during rapid-eye-movement sleep. J Appl Physiol 1983;54(3):632–9. 37. Goldstein RS, Ramcharan V, Bowes G, McNicholas WT, Bradley D, Phillipson EA. Effect of supplemental nocturnal oxygen on gas exchange in patients with severe obstructive lung disease. N Engl J Med 1984;310(7):425–9. 38. Guilleminault C, Kurland G, Winkle R, Miles LE. Severe kyphoscoliosis, breathing, and sleep: the “Quasimodo” syndrome during sleep. Chest 1981;79(6):626–30. 39. Mezon BL, West P, Israels J, Kryger M. Sleep breathing abnormalities in kyphoscoliosis. Am Rev Respir Dis 1980;122(4):617–21. 40. Goldstein RS, Molotiu N, Skrastins R, et al. Reversal of sleep-induced hypoventilation and chronic respiratory failure by nocturnal negative pressure ventilation in patients with restrictive ventilatory impairment. Am Rev Respir Dis 1987;135(5):1049–55.
82
Diagnostic studies for sleep apnea/hypopnea
41. American Sleep Disorders Association. EEG arousals: scoring rules and examples. Sleep 1992;15:173. 42. Agnew Jr. HW, Webb WB, Williams RL. The first night effect: an EEG study of sleep. Pyschophysiology 1966;2(3):263–6. 43. Wittig RM, Romaker A, Zorick FJ, Roehrs TA, Conway WA, Roth T. Night-to-night consistency of apneas during sleep. Am Rev Respir Dis 1984;129(2):244–6. 44. Fisher JG, Garza G, Flickinger R, de la Pena A. An alternate method of recording airflow during sleep. Sleep 1980;2(4):461–3. 45. Krumpe PE, Cummiskey JM. Use of laryngeal sound recordings to monitor apnea. Am Rev Respir Dis 1980;122(5):797–801. 46. Cummiskey J, Williams TC, Krumpe PE, Guilleminault C. The detection and quantification of sleep apnea by tracheal sound recordings. Am Rev Respir Dis 1982;126(2):221–4. 47. Peirick J, Shepard Jr. JW, Automated apnoea detection by computer: analysis of tracheal breath sounds. Med Biol Eng Comput 1983;21:632–5. 48. Norman RG, Ahmed MM, Walsleben JA, Rapoport DM. Detection of respiratory events during NPSG: nasal cannula/pressure sensor versus thermistor. Sleep 1997;20(12):1175–84. 49. Berg S, Haight JS, Yap V, Hoffstein V, Cole P. Comparison of direct and indirect measurements of respiratory airflow: implications for hypopneas. Sleep 1997;20(1):60–4. 50. Fleury B, Rakotonanahary D, Hausser-Hauw C, Lebeau B, Guilleminault C. A laboratory validation study of the dignostic mode of the Autoset system for sleep-related respiratory disorders. Sleep 1996;19(6):502–5 [erratum appears in Sleep 1996;19(7):601]. 51. Farre R, Montserrat JM, Rotger M, Ballester E, Navajas D. Accuracy of thermistors and thermocouples as flow-measuring devices for detecting hypopnoeas. Eur Respir J 1998;11(1):179–82.
52. Cohn MA, Rao AS, Broudy M, et al. The respiratory inductive plethysmograph: a new non-invasive monitor of respiration. Bull Eur Physiopathol Respir 1982;18(4):643–58. 53. Larsen VH, Christensen PH, Oxhoj H, Brask T. Impedance pneumography for long-term monitoring of respiration during sleep in adult males. Clin Physiol 1984;4(4):333–42. 54. Sampson MG, Walskben JA. Effect of esophageal balloon on sleep structure (abstract). Sleep Res 1984;13:211. 55. Chadha TS, Watson H, Birch S, et al. Validation of respiratory inductive plethysmography using different calibration procedures. Am Rev Respir Dis 1982;125(6):644–9. 56. Stradling JR, Chadwick GA, Quirk C, Phillips T. Respiratory inductance plethysmography: calibration techniques, their validation and the effects of posture. Bull Eur Physiopathol Respir 1985;21:317–24. 57. Staats BA, Bonekat HW, Harris CD, Offord KP. Chest wall motion in sleep apnea. Am Rev Respir Dis 1984;130(1):59–63. 58. Gugger M, Gould GA, Whyte KF, et al. Inductive plethysmographs do not accurately measure ventilation during sleep in unrestrained subjects (abstracts). Am Rev Respir Dis 1987;135(suppl):A50. 59. Spier S, England S. The respiratry inductive plethysmograph: bands versus jerkins. Am Rev Respir Dis 1983;127(6):784–5. 60. Zimmerman PV, Connellan SJ, Middleton HC, Tabona MV, Goldman MD, Pride N. Postural changes in rib cage and abdominal volume–motion coefficients and their effect on the calibration of a respiratory inductance plethysmograph. Am Rev Respir Dis 1983;127(2):209–14. 61. Surez M, Bizousky R, Befeler A, Sackner MA. Performance of mecury in silastic strain gauges and respiratory inductive pletyhsmograph as assessed with spirometry (abstract). Am Rev Respir Dis 1987;135(suppl):A49.
References 62. Zolty P, Sanders MH, Pollack IF. Chiari malformation and sleep-disordered breathing: a review of diagnostic and management issues. Sleep 2000;23(5):637–43. 63. Series F, Marc I, Cormier Y, La Forge J. Utility of nocturnal home oximetry for case finding in patients with suspected sleep apnea hypopnea syndrome. Ann Inter Med 1993;119(6):449–53. 64. Farre R, Montserrat JM, Ballester E, Hernandez L, Rotger M, Navajas D. Importance of the pulse oximeter averaging time when measuring oxygen desaturation in sleep apnea. Sleep 1998;21(4):386–90. 65. Gardner R. Snowbird workshop on standardization of spirometry. Am Rev Respir Dis 1979;119:831. 66. Grace RF. Pulse oximetry. Gold standard or false sense of security? Med J Aust 1994;160(10):638–44. 67. Poets CF, Southall DP. Noninvasive monitoring of oxygenation in infants and children: practical considerations and areas of concern. Pediatrics 1994;93(5): 737–46. 68. Mengelkoch LJ, Martin D, Lawler J. A review of the principles of pulse oximetry and accuracy of pulse oximeter estimates during exercise. Phys Ther 1994;74(1):40–9. 69. Barker SJ, Tremper KK. The effect of carbon monoxide inhalation on pulse oximetry and transcutaneous PO2. Anesthesiology 1987;66(5):677–9. 70. Hampson NB. Pulse oximetry in severe carbon monoxide poisoning.Chest 1998;114(4):1036–41. 71. Severinghaus JW, Kelleher JF. Recent developments in pulse oximetry. Anesthesiology 1992;76(6):1018–38. 72. Barker SJ, Tremper KK, Hyatt J. Effects of methemoglobinemia on pulse oximetry and mixed venous oximetry. Anesthesiology 1989;70(1):112–17. 73. Wright RO, Lewander WJ, Woolf AD. Methemoglobinemia: etiology,
74. 75. 76.
77.
78.
79.
80.
81.
82. 83.
84.
85.
83
pharmacology, and clinical management. Ann Emerg Med 1999;34(5):646–56. Stoneham MD. Uses and limitations of pulse oximetry. Br J Hosp Med 1995;54(1):35–41. Tallon RW. Oximetry: state-of-the-art. Nurs Manage 1996;27(11):43–4. Lindberg LG, Lennmarken C, Vegfors M. Pulse oximetry–clinical implications and recent technical developments. Acta Anaesthesiol Scand 1995;39(3):279–87. Ortiz FO, AldrichTK, Nagel RL, Benjamin LJ. Accuracy of pulse oximetry in sickle cell disease. Am J Respir Crit Care Med 1999;159(2):447–51. Mendelson Y. Pulse oximetry: theory and applications for noninvasive monitoring. Clin Chem 1992;38(9):1601–7. Slutsky AS, Strohl KP. Quantification of oxygen saturation during episodic hypoxemia. Am Rev Respir Dis 1980;121(5):893–5. Berkani M, Lofaso F, Chouaid C, et al. CPAP titration by an auto-CPAP device based on snoring detection: a clinical trial and economic considerations. Eur Respir J 1998;12(4):759–63. Ayappa I, Norman RG, Hosselet JJ, Gruenke RA, Walsleben JA, Rapoport DM. Relative occurrence of flow limitation and snoring during continuous positive airway pressure titration. Chest 1998;114(3):685–90. Cartwright RD. Effect of sleep position on sleep apnea severity. Sleep 1984;7(2):110–14. Pascal-Sebaoun S, Milosevic D, Orvoen-Frija E, Leger D, Basdevant A, Laaban JP. [Value of Holter ECG in the diagnosis of sleep apnea syndrome in patients with massive obesity]. Presse Med 2000;29(1):11–16. Keyl C, Lemberger P, Pfeifer M, Hochmuth K, Geiseler P. Heart rate variability in patients with daytime sleepiness suspected of having sleep apnoea syndrome: a receiveroperating characteristic analysis. Clin Sci (Colch) 1997;92(4):335–43. Lloberes P, Ballester E, Montserrat JM, et al. Comparison of manual and automatic CPAP titration in patients with sleep
84
86.
87.
88.
89.
90.
91.
92.
93.
94.
Diagnostic studies for sleep apnea/hypopnea apnea/hypopnea syndrome. Am J Respir Crit Care Med 1996;154(6 Pt 1):1755–8. Stradling JR, Barbour C, Pitson DJ, Davies RJ. Automatic nasal continuous positive airway pressure titration in the laboratory: patient outcomes. Thorax 1997;52(1):72–5. Sanders MH, Black J, Costantino JP, Kern N, Studnicki K, Coates J. Diagnosis of sleepdisordered breathing by half-night polysomnography. Am Rev Respir Dis 1991;144(6):1256–61. Iber C, O’Brien C, Schluter J, Davies S, Leatherman J, Mahowald M. Single night studies in obstructive sleep apnea. Sleep 1991;14(5):383–5. Yamashiro Y, Kryger MH. CPAP titration for sleep apnea using a split-night protocol. Chest 1995;107(1):62–6. Sullivan CE, Issa FG, Berthon-Jones M, McCauley VB, Costas LJ. Home treatment of obstructive sleep apnoea with continuous positive airway pressure applied through a nose-mask. Bull for Physiopathol Respir 1984;20:49–54. Strollo Jr. PJ, Sanders MH, Costantino JP, Walsh SK, Stiller RA, Atwood Jr. CW. Splitnight studies for the diagnosis and treatment of sleep-disordered breathing. Sleep 1996;19(10 Suppl):S255–9. Fleury B, Rakotonanahary D, Tehindrazanarivelo AD, Hausser-Hauw C, Lebeau B. Long-term compliance to continuous positive airway pressure therapy (nCPAP) set up during a split-night polysomnography. Sleep 1994;17(6):512–15. Sanders MH, Kern NB, Costantino JP, et al. Prescription of positive airway pressure for sleep apnea on the basis of a partial-night trial. Sleep 1993;16(8 Suppl):S106–7. Chervin RD, Murman DL, Malow BA, Totten V. Cost-utility of three approaches to the diagnosis of sleep apnea: polysomnography, home testing, and empirical therapy. Ann Intern Med 1999;130(6):496–505.
95. Schmidt-Nowara W. The utility of a CO2 home monitor respisomnograph in the diagnosis of sleep apnea syndrome (abstract). Sleep Res 1985;14:279. 96. Salmi T, Leinonen L. Automatic analysis of sleep records with static charge sensitive bed. Electroencephalogr Clin Neurophysiol 1986;64(1):84–7. 97. Svanborg E, Larsson H. Screening of obstructive sleep apnea with respiration movement and SaO2 monitoring: high diagnostic accuracy in comparison with polygraphic recordings (abstract). Sleep Res 1987;16:587. 98. Standards of Practice Committee of the American Sleep Disorders Association. Practice parameters for the use of portable recording in the assessment of obstructive sleep apnea. Sleep 1994;17(4):372–7. 99. Redline S, Tosteson T, Boucher MA, Millman RP. Measurement of sleep-related breathing disturbances in epidemiologic studies. Assessment of the validity and reproducibility of a portable monitoring device. Chest 1991;100(5): 1281–6. 100. White DP, Gibb TJ, Wall JM, Westbrook PR. Assessment of accuracy and analysis time of a novel device to monitor sleep and breathing in the home. Sleep 1995;18(2):115–26. 101. Waldhorn RE, Wood K. Attended home titration of nasal continuous positive airway pressure therapy for obstructive sleep apnea. Chest 1993;104(6):1707–10. 102. Fletcher EC, Stich J, Yang KL. Unattended home diagnosis and treatment of obstructive sleep apnea without polysomnography. Arch Fam Med 2000;9(2):168–74. 103. Meyer TJ, Eveloff SE, Kline LR, Millman RP. One negative polysomnogram does not exclude obstructive sleep apnea. Chest 1993;103(3):756–60. 104. Farney RJ, Walker LE, Jensen RL, Walker JM. Ear oximetry to detect apnea and differentiate rapid eye movement (REM) and
References
105.
106.
107.
108.
109.
110.
111.
112.
non-REM (NREM) sleep. Screening for the sleep apnea syndrome. Chest 1986;89(4):533–9. Douglas NJ, Thomas S, Jan MA. Clinical value of polysomnography. Lancet 1992;339(8789):347–50. Pack AI. Simplifying the diagnosis of obstructive sleep apnea (editorial). Ann Inter Med 1993;119(6):528–9. Schwab RJ, Gupta KB, Gefter WB, Metzger LJ, Hoffman EA, Pack AI. Upper airway and soft tisue anatomy in normal subjects and patients with sleep-disordered breathing. Significance of the lateral pharyngeal walls. Am J Respir Crit Care Med 1995;152(5 Pt 1):1673–89. Hudgel DW. The role of upper airway anatomy and physiology in obstructive sleep apnea. Clin Chest Med 1992;13(3):383–98. van Lunteren E. Muscles of the pharynx: structural and contractile properties. Ear Nose Throat J 1992;13(3):383–98. Galvin JR, Rooholamini SA, Stanford W. Obstructive sleep apnea: diagnosis with ultrafast CT. Radiology 1989;171(3):775–8. Shepard Jr. JW, Thawley SE. Evaluation of the upper airway by computerized tomography in patients undergoing uvulopalatopharyngoplasty for obstructive sleep apnea. Am Rev Respir Dis 1989;140(3):711–16. Schwab RJ, Gefter WB, Hoffman EA, Gupta KB, Pack AI. Dynamic upper airway imaging during awake respiration in normal subjects and patients with sleep disordered
113.
114.
115.
116.
117.
118.
119.
85
breathing. Am Rev Respir Dis 1993;148(5):1385–400. Schwab RJ, Gefter WB, Pack AI, Hoffman EA. Dynamic imaging of the upper airway during respiration in normal subjects. J Appl Physiol 1993;74(4):1504–14. Horner RL, Shea SA, McIvor J, Guz A. Pharyngeal size and shape during wakefulness and sleep in patients with obstructive sleep apnoea. Q J Med 1989;72(268):719–35. Suto Y, Matsuo T, Kato T, et al. Evaluation of the pharyngeal airway in patients with sleep apnea: value of ultrafast MR imaging. Am J Roentgenol 1993;160(2):311–14. Riley R, Guilleminault C, Powell N, Simmons FB. Palatopharyngoplasty failure, cephalometric roentgenograms, and obstructive sleep apnea. Otolaryngol Head Neck Surg 1985;93(2):240–4. Sher AE, Thorpy MJ, Shprintzen RJ, Spielman AJ, Burack B, McGregor PA. Predictive value of Muller maneuver in selection of patients for uvulopalatopharyngoplasty. Laryngoscope 1985;95(12):1483–7. Doghramji K, Jabourian ZH, Pilla M, Farole A, Lindholm RN. Predictors of outcome for uvulopalatopharyngoplasty. Laryngoscope 1995;105(3 Pt 1):311–4. Naya M, Vicente E, Llorente E, Marin C, Damborenea J. [Predictive value of the Müller maneuver in obstructive sleep apnea syndrome]. Acta Otorrinolaringol Esp 2000;51(1):40–5.
II Therapy
5
Medical therapy
Richard B Berry
Indications for treatment The indications for treatment of obstructive sleep apnea (OSA) have expanded since the original description of the syndrome. It is now recognized that milder forms of this disorder can be associated with daytime sleepiness1–6 and that treatment can improve symptoms and the quality of life.4–6 Over a decade ago, it was recognized that obstructive hypopnea (reductions in airflow during periods of high upper airway resistance) had the same consequences as obstructive apnea.7 The frequency of apneas and hypopneas are added to determine the apnea hypopnea index (AHI) as an indicator of disease severity. Subsequently, the upper airway resistance syndrome (UARS) was described in patients with daytime sleepiness but little or no apnea, hypopnea, or desaturation. They exhibited repetitive arousals (brief awakenings) associated with episodes of increased inspiratory effort demonstrated by esophageal pressure monitoring. The sleepiness of these patients improved after treatment of the upper airway narrowing. Arousal from respiratory stimuli is related to the level of inspiratory effort and can occur in the absence of apnea or desaturation.8 Experimentally induced repetitive arousals have been demonstrated to cause daytime sleepiness in normal individuals in the absence of arterial oxygen desaturation.9 Thus, daytime sleepiness in
UARS is believed to occur secondary to arousals from increased respiratory effort during periods of high upper airway resistance. The term respiratory effort-related arousals (RERAs) has recently been widely adopted to describe events characterized by increased respiratory effort leading to arousal from sleep which do not meet criteria for apnea or hypopnea.10 The recognition of the importance of RERAs has led to the understanding that the AHI alone may not adequately characterize the degree of respiratory-induced sleep disturbance in individuals with ‘milder OSA’. Rather than being a separate syndrome, most now feel that the upper airway resistance syndrome is simply part of the spectrum moving from non-arousing snoring at the milder end to full-blown sleep apnea at the severe end. While many will agree with this concept, how to utilize RERAs is still somewhat controversial. A consensus conference suggested that the RERA index be added to the AHI to give a true respiratory disturbance index (RDI).11 This assumes that RERAs and apnea/hypopneas disturb sleep equally (not proven). However, as most laboratories do not utilize esophageal pressure monitoring, precise identification of RERAs may be difficult. Recently, the use of nasal pressure or pneumotachograph monitoring of airflow rather than thermistors has been
90
Medical therapy
utilized to identify periods of airflow limitation (inspiratory flattening). A period of flattening followed by the abrupt return of a round airflow profile has been thought to correctly identify periods of increased upper airway resistance.12 Thus, RERAs could be identified by a pattern of flow limitation followed by arousal and reversal of flow limitation. However, almost all population studies have used thermistors, so little normative information is available with this technique. Another controversial point is whether one should count flow-limited events not associated with arousals. Certainly, not all apneas and hypopneas are associated with clear-cut cortical arousal.8 Events associated only with abrupt change in respiration/heart rate/blood pressure also appear to cause daytime sleepiness.13 If RERAs can be accurately identified, what number should be considered abnormal? Mathur and colleagues demonstrated that normal adults may have an arousal index up to 25/h.14 Therefore, one might guess that an RDI (AHI + RERA index) of around 30/h would be the range at which significant sleep disturbance would occur. Hosselet et al12 identified a flow limitation event index of 30/h as separating symptomatic from asymptomatic individuals. However, they also suggested that an AHI higher than 5/h may be needed for separation of symptomatic individuals when nasal pressure monitoring rather than thermistor flow is used to define the AHI. At this point, no absolute recommendations about what constitutes an abnormal RERA index can made. Definitions of normality, whether based on the AHI, AHI + RERA index, or AHI + a flow limitation index, will certainly depend on the technology used to detect events. What is clear is that a patient with an AHI of 10/h and a RERA index of 30/h is having a significant rate of respiratory arousals per hour, and therefore
it is not surprising that such a patient with ‘mild’ sleep apnea by conventional criteria might be quite symptomatic. In determining an indication for treatment, most physicians evaluate both the RDI (or AHI) and whether or not the patient is symptomatic (daytime sleepiness). Possible detrimental effects from severe hypoxia and evidence of cardiac or neurologic compromise are also considered. Obviously, patients with right heart failure, severe nocturnal hypoxemia or daytime hypercapnia should be treated. In general, the threshold for treating symptomatic patients is lower. For example, a recent consensus conference on positive-pressure treatment suggested that symptomatic patients with an RDI (AHI + RERA index) > 5/h be treated as well as all patients with an RDI > 30/h (with or without symptoms).11 Previous studies of patients with the UARS and two recent studies of patients with an AHI of 5–15/h have clearly demonstrated that patients with milder disease can benefit from treatment, with respect to daytime alertness and quality of life.4–6 Therefore, most physicians would treat sleepy patients with even ‘mild disease’. One caution is that the presence of snoring and mild OSA does not preclude the coexistence of other disorders such as narcolepsy or periodic leg movements in sleep. More than one patient has undergone ‘ineffective’ treatment of mild OSA with nasal CPAP while a another significant sleep disorder went unrecognized and untreated. Most clinicians would also recommend treatment of all patients with moderate to severe OSA (RDI (as defined above) > 30/h or AHI > 20/h), whether or not they are symptomatic. Such patients, if sleepy, should expect clear subjective benefit from successful treatment. A more difficult dilemma is the patient who steadfastly denies any symptoms. Such patients are less likely to perceive a subjective benefit and may be less likely to comply with
Weight loss treatment. What is the evidence for benefit in treating asymptomatic patients with OSA? A frequently quoted retrospective study by He et al15 reported a decrease in survival in untreated OSA patients with an apnea index > 20. Successful treatment with tracheostomy or continuous positive airway pressure (CPAP) normalized the survival. This suggests a benefit from effective treatment apart from symptoms. However, some have challenged the importance of OSA as a health risk.16 More rigorous demonstration of an independent survival risk for untreated OSA awaits results from studies such as the Sleep Heart Health study, which has documented some increase in risk for even relatively mild increases in the AHI.17 Until that time, patients can be told that there is reasonable preliminary evidence that the OSA may negatively impact on other comorbid disorders, such as atherosclerotic heart disease, congestive heart failure and hypertension. Some of this evidence is discussed in more detail in the section on positive-pressure treatment. This chapter will discuss two important medical treatment options: weight loss and positive pressure. As noted below, weight loss alone may be a valid treatment of mild OSA and adjunctive in moderate to severe disease in patients with a wide range of obesity. Positive pressure has traditionally been the treatment of choice for moderate to severe OSA.1,2 Studies have demonstrated that positive pressure can be effective in milder disease, although problems with acceptance and compliance may be even greater than in patients with more severe disease.6
Weight loss Many studies have demonstrated that obesity is a major risk factor for the development of
91
OSA. A clinic population study of OSA patients found that approximately two-thirds were obese (body weight > 120% of predicted).1 A population-based study of 6000 Wisconsin state employees (men and women) between 30 and 60 years of age supports the above findings.3 In the Wisconsin study, an increase in body mass index (BMI) of one standard deviation was associated with a fourfold increase in the risk of sleep-disordered breathing (AHI > 5/h). Neck size was the strongest predictor, suggesting that upper body obesity is especially important. Other studies have also suggested that the distribution as well as the total amount of body fat is an important determinant of the risk for developing OSA.18 Given that obesity is an important risk factor for OSA, it is not surprising that weight loss is an important potential treatment. The benefits are not confined to patients with severe obesity, and relatively modest weight loss can have dramatic effects in individual patients.19,20 Nevertheless, to get patients to lose weight and then maintain the weight loss is a difficult task. The mechanisms by which obesity causes OSA or weight loss decreases OSA are still not known. Direct effects on upper airway anatomy (fat deposits in or near the upper airway/changes in pharyngeal muscles) or indirect changes secondary to changes in lung volume are two possible explanations for the effect of obesity on upper airway patency. One magnetic resonance (MR) study of the upper airway in OSA patients found that the amount of fat deposition near the upper airway correlated with the AHI.21 Two OSA patients who improved after weight loss also showed a decrease in fat around the pharynx. Another MR study comparing obese OSA patients and weight-matched controls found an increase in adipose deposition in the OSA patients in areas posterior and lateral to the oropharynx at the
92
Medical therapy
Figure 5.1 The effect of weight loss on the lateral pharyngeal wall. Axial MR images during wakefulness at the retropalatal region in a normal subject before weight loss (A) and after weight loss (B). After weight loss, there was a decrease in size of the lateral pharyngeal wall and an increase in lateral airway dimensions. (Reprinted with permission, from Schwab.23)
level of the palate.22 Later MR studies have shown that, while obese OSA patients do have more pharyngeal fat, the main change in upper airway size is secondary to the thickness of the lateral pharyngeal muscular walls rather than enlargement of the parapharyngeal fat pad.23 The cause of the thickening of the lateral pharyngeal muscles is not known, but weight loss decreases the thickness (Figure 5.1). The lateral wall changes make the shape of the airways of OSA different from those of normal subjects. In cross-section, the OSA airway is somewhat elliptical with the long axis in the anterior–posterior direction, while in normal subjects the long axis is in the lateral direction. Thus, the upper airway of OSA patients tends to be smaller in size and narrowed in the lateral dimension. Weight loss probably increases the airway size in that dimension.
The size of the upper airway varies with lung volume24 probably secondary to the effects of tracheal displacement (tracheal tug).25 Obesity reduces supine lung volume, and this may be another mechanism by which it reduces upper airway size. Weight loss appears to reduce the lung volume dependence of the pharyngeal area.26 Whatever the mechanism, studies have also shown that the collapsibility of the upper airway is decreased by weight loss, implying that obesity increases the tendency of the upper airway to collapse as well as decreasing the size.27 While early studies showed improvements after major weight reduction,28 other studies have documented that weight loss of even modest proportions (5–10%) can produce significant improvement in sleep apnea.20 The results will vary between patients. A given
Positive airway pressure amount of weight loss may have more effect on upper body obesity in some patients. Even patients with mild obesity (110–115% of ideal body weight) may benefit from weight reduction. Weight loss decreases the AHI but not always to acceptable levels (< 5/h). However, a reduction in collapsibility will often allow a lower level of nasal CPAP to maintain upper airway patency.27 Surgical, behavioral (traditional and very low calorie diets) and medication approaches to weight loss have all been successful in selected groups of patients.19,20,26–29 While some former anorexiant medications have been removed from the market because of an association with pulmonary hypertension, new drugs are rapidly appearing (but are often quite expensive). Surprisingly few studies have addressed the benefits of medicine for weight loss in OSA patients. However, while induction of weight loss is difficult, another major problem has been maintenance of weight loss. Sampol et al studied 216 overweight OSA patients treated by weight reduction alone.30 Twenty-four were cured by this method. After a mean follow-up period of 94 months, 13/24 patients had maintained weight loss. Even in these 13, OSA recurred in 6. Other studies have reported a recurrence of OSA after weight loss.31 Thus, periodic follow-up is required to reinforce weight loss maintenance and to check for symptoms of OSA recurrence. Because different patients have different patterns of weight loss, it is not possible to predict which patients will respond or how much weight loss is needed. In general, weight loss is most effective as a primary treatment in patients with milder OSA. In more severe patients, it is prudent to begin treatment with nasal CPAP while initiating a weight loss program. Noseda et al attempted weight loss while 39 patients were being treated with nasal CPAP for 1 year.
93
However, only 3 of the 39 with weight loss could be weaned from CPAP.32 In summary, while weight loss shows promise as a treatment for sleep apnea, its widespread use as a primary treatment for other than mild disease probably awaits effective and safe medicines which will help patients lose and maintain weight loss.
Positive airway pressure Since the original description of nasal CPAP as a treatment for obstructive sleep apnea,33 positive pressure has become the mainstay of treatment for moderate to severe obstructive sleep apnea.2,10,33–36 However, patients with mild OSA,5–6 the upper airway resistance syndrome,4 or even heavy snoring37,38 have also been treated successfully with positive pressure. Since the original description of CPAP, there have been major technological improvements in delivery systems and masks. Objective compliance data are now available on most machines. However, the major challenge to the clinician is still to get patients to first accept and then to comply with positive airway pressure treatment.
Mechanism of action The mechanism of action of positive airway pressure is believed to be primarily a pneumatic splint effect on the upper airway (Figure 5.2). During application of CPAP, upper airway muscle activity decreases, implying a passive distension of the upper airway.39–42 Studies using CT or MRI have documented that CPAP does dilate the upper airway at multiple locations.43–44 In particular, there appears to be a dilation of the lateral
94
Medical therapy
+
+
+ +
A
– – – – – – –– – – –
+ + +
Figure 5.2 The pneumatic splint mechanism by which nasal positive airway pressure maintains upper airway patency is illustrated here. (A) without a mask; (B) with a nasal mask.
+
B
dimensions of the upper airway.44 Dynamic imaging studies of the upper airway have also shown that the smallest area occurs at end exhalation.45 This may explain why application of expiratory positive airway pressure alone induces some improvement in upper airway patency.46 Positive airway pressure may also have some indirect effects on the upper way via changes in lung volume.47 However, it appears that this is not the major mechanism by which positive airway pressure maintains upper airway patency.48,49 As the level of positive pressure is increased, first apnea, and then hypopnea and desaturation, are abolished. At higher pressure levels, snoring is also prevented. However, evidence of airflow limitation and high upper airway resistance may still persist. Sometimes, only a few additional centimeters of H2O pressure are required for normalizing inspiratory effort (esophageal pressure swings).50
Methods of delivery of positive pressure Currently available modes of delivering positive airway pressure are listed in Table 5.1. CPAP remains the standard method to provide
Table 5.1 Positive-pressure devices and patient interfaces. Positive-pressure devices Patient interfaces Continuous positive airway pressure (CPAP) Bilevel pressure Auto-titrating CPAP Volume-cycled ventilation
Nasal masks Nasal prongs (pillows) Full facemasks (oronasal)
positive pressure for upper airway stabilization.2,11,33–36,50,51 A blower unit provides a flow of air sufficient to maintain a constant pressure during the respiratory cycle and to overcome leaks in the system. A nasal mask is the common interface.52 The palate moves forward against the tongue, preventing oral leaks (Figure 5.2). Nasal prongs (pillows) and full facemasks53–55 are also utilized in some patients. In general, a good seal is more difficult to obtain with full facemasks (oronasal) than with nasal masks. All systems have a facility to wash out exhaled carbon dioxide. This is usually accomplished by a controlled leak through a hole or set of holes in the mask or in a small
Positive airway pressure
A
B
C
D
95
E
Figure 5.3 Several current types of interfaces for positive-pressure delivery are shown here. (A) Nasal pillows (prongs) (Breeze™ headgear, Mallinckrodt: Minneapolis, MN, USA). (B) Nasal mask (Contour™, Respironics: Pittsburgh, PA, USA). (C) Nasal mask (UltraMirage™, ResMed: San Diego, CA, USA). (D) Nasal mask (Simplicity™, Respironics: Pittsburgh, PA, USA). (E) A full facemask (Mirage™, ResMed: San Diego, CA, USA).
section of tubing connecting the hose from the blower unit to the mask (Whisper Swivel™, Respironics). In Figure 5.3, several different types of masks are shown, including nasal and full facemasks and nasal prongs (pillows). Bilevel pressure, in which different pressures are delivered in inspiration (inspiratory positive airway pressure (IPAP)) and expiration (expiratory positive airway pressure (EPAP)) has also been shown to be effective.56 The machine cycles into the expiratory mode when inspiratory airflow reaches a threshold value, and cycles into inspiration when inspiratory flow is detected. Bilevel pressure may allow airway stabilization with a lower pressure during exhalation. In addition, this method can deliver non-invasive pressure support (IPAP – EPAP) as well as maintain upper airway patency.57 While bilevel pressure devices are more expensive than CPAP blower units, they can certainly increase acceptance of positive pressure in some cases. Patients requiring high pressure, those with hypoventilation, some patients with mouth leaks, or patients with chronic obstructive pulmonary or muscle weakness of any cause, may accept
bilevel pressure but not CPAP. However, for unselected OSA patients, there is no evidence that bilevel pressure increases compliance.58 In both CPAP and bilevel pressure, a fixed prescription pressure is given, based on some type of pressure titration study. A third method of delivering positive pressure is an auto-titrating device (‘smart CPAP’).59–64 This type of machine adjusts pressure according to set algorithms that vary between commercial devices. The devices monitor one or more of the following: vibration in the airways (snoring), flow (apnea and hypopnea), inspiratory flow shape (flattening), impedance (forced oscillation) or a combination (snoring, flow, flattening). In most devices, a lower and upper bound for pressures may also be set. Many auto-titrating units can store pressure and leak information in downloadable memory. The delivered airway pressures and leak and flow characteristics during the night are then available. One can prescribe a fixed prescription pressure using a traditional CPAP blower on the basis of pressures needed during the auto-titration night(s). For example, one could use the maximum or 90–95th percentile pressure
96
Medical therapy
(90–95% of time at that pressure or below). Auto-titrating units could potentially allow a technician to titrate more patients or perform unattended titration, either in the hospital or at home. Some units, by recording the number of respiratory events, also provide a means of diagnosis. Alternatively, the same devices could be used for chronic treatment (auto-adjusting). By varying the airway pressure according to changing requirements during the night, autotitrating devices could potentially increase compliance, as a lower mean pressure may be administered. To date, there has not been convincing evidence that these units will increase compliance enough in unselected patients to justify the extra cost. These issues will be discussed in the titration and compliance sections to follow. A final, rarely used method of positive pressure is to utilize volume cycle ventilation with positive end expiratory pressure (PEEP) via a nasal or full facemask interface. The method has been most frequently used in the initial treatment of severe OSA associated with respiratory failure in patients with an acceptable level of consciousness.65 One problem is that most ventilators will alarm repeatedly with the small leaks inevitable in this setting. Recent models of some ventilators now allow raising the threshold for the leak alarm, and may be more useful for this mask ventilation. As some bilevel pressure flow devices can now generate up to 35 cmH2O, volume-cycled ventilation may not be required for even the most severe patients. The relative advantages of the above modes of positivepressure application will be discussed below.
Determination of prescription pressure Traditionally, the level of positive pressure prescribed for the patient is chosen during full-
or partial-night study in the laboratory during conventional polysomnography. The partialnight titration follows an initial diagnostic portion (split study). While the partial night approach is effective for 60–80% of patients66–68 and has economic benefits, it does shorten both diagnostic and positive-pressure titration portions of the study. In patients showing predominant events in either the supine position or during REM sleep, a shortened diagnostic portion may contain little supine or REM sleep and therefore result in an underestimation of the severity of sleep apnea. Many laboratories encourage the patient to sleep supine as much as possible and to include at least one REM period in the diagnostic portion of the study. Split-night studies also shorten the CPAP titration. Sometimes, inadequate REM sleep or little sleep in the supine position are recorded at the final pressure. This may be important, because higher pressures are usually needed to stabilize the upper airway in the supine position and during REM sleep.69 The protocols for titration also vary between laboratories. One must understand that a CPAP trial is both a determination of efficacy and a desensitization to wearing a mask and sleeping with positive pressure. In general, the sleep technician must gauge both the effectiveness of a given level of pressure and tolerance. Thus, temporary reductions in pressure are sometimes required to allow a patient to return to sleep. Many laboratories utilize a positive-pressure treatment table, demonstrating in tabular form the amount and type of apnea/hypopnea, the stages of sleep present, predominant body position, and arterial oxygen saturation at a given pressure or pressure range. For example, in Table 5.2a, one sees that adequacy of treatment at the final pressure was not documented in the supine position during REM sleep. In Table 5.2b, a more ideal titration is shown.
Positive airway pressure
97
Table 5.2 Examples of positive-pressure treatment tables. (a) CPAP Monitoring time (min) Non-REM (min) REM (min) AHI (/h) % of events Obstructive + mixed apnea Central apnea Hypopnea Body position
0 (diagnostic) 180 150 10 75
5.0 40 20 10 60
7.5 60 40 10 30
10 60 40 0 20
12.5 40 30 0 10
100 0 0 Supine
90 0 10 Supine
50 0 50 Lateral
10 0 90 Lateral
0 5 95 Lateral
0 (diagnostic) 120 90 0 75
5.0 60 35 10 60
7.5 60 45 10 30
10 60 30 10 15
12.5 80 20 40 5
75 5 20 Supine
60 0 40 Supine
50 0 50 Lateral
35 5 60 Supine
0 5 95 Supine
(b) CPAP Monitoring time (min) Non-REM (min) REM (min) AHI (/h) % of events Obstructive + mixed apnea Central apnea Hypopnea Body position
A commonly used titration endpoint (see Table 5.3) is to increase positive pressure until apnea, hypopnea, desaturation and snoring are abolished or dramatically reduced. An additional goal is the elimination of RERAs. However, it is not always clear to a technician exactly what is causing repetitive arousals. Direct measurement of esophageal pressure deflections can allow titration until the pressure swings are less than 10 cmH2O.50 Such monitoring is not widely utilized. Others have suggested that the presence of flattening in the inspiratory flow contour (flow limitation) is evidence of persistent elevation in upper airway resistance70 (Figure 5.4). Thermistors do not provide an accurate
Table 5.3 Titration endpoints. Elimination of apnea, hypopnea, desaturation Elimination of snoring Elimination of respiratory effort-related arousals (RERAs) Elimination of increased respiratory effort (requires esophageal pressure monitoring) Elimination of airflow limitation (requires accurate airflow monitoring)
estimate of either flow or the flow versus time profile. Most diagnostic positive-pressure devices have an output utilizing a built-in
98
Medical therapy
CPAP (cm H2O)
14 13 12 11 10
Total flow (l/min)
50 40 30 20 10
Press. Esoph. (cm H2O)
0 4 2 0 –2 –4 Resistance = 12
–6 0
5
Resistance = 29 10
15
20
25
30
Time (seconds)
Figure 5.4 Airflow limitation (inspiratory flattening) during reduction of nasal pressure is shown coincident with increases in esophageal pressure deflections (increased upper airway resistance). (Reprinted from Condos et al.70 with permission.)
pneumotachograph to provide an accurate estimate of flow and system leak. Respiratory impedance determined by the forced oscillation technique has recently been proposed as an alternative to using the airflow profile (flattening) to detect high residual amounts of upper airway resistance.71 Most would recommend that positive pressure should be increased until RERAs are eliminated. Should positive pressure be increased until no flow limitation is present?
The presence of some flow limitation may not be detrimental. Meurice et al72 compared titration to overcome apnea, hypopnea, desaturation and snoring (standard endpoint with a protocol to eliminate flow limitation (PFL)). They found that the PFL group required about an additional 1.5 cmH2O. At the end of a 3week home CPAP treatment trial, the two groups were restudied. There was no difference in sleep quality or daytime vigilance tests between the two groups. The PFL group had a
Positive airway pressure higher nightly compliance (on average greater than 1 h), and the standard endpoint group showed more variability in improvement in sleep latency on the maintenance of wakefulness test (MWT). The difference in compliance makes it difficult to prove that the PFL titration endpoint resulted in better reversal of daytime sleepiness. However, one might propose that the higher compliance was secondary to an increased perceived benefit. In any case, the study does suggest that the addition of a few cm H2O pressure will not reduce compliance. A reasonable pressure titration approach would be to increase pressure to abolish arousals associated with flow limitation or severe flow limitation, even in the absence of arousals. Further upward pressure titration to abolish milder degrees of flow limitation could be attempted so long as this did not induce patient intolerance or intractable air leaks. Ultimately, the prescription pressure is always a compromise between what is optimum for maintaining airway patency and high-quality sleep and what the patient will tolerate (side-effects). Titration protocols for bilevel pressure also vary between sleep centers. A simple and effective approach is to titrate up (IPAP = EPAP) until apnea is abolished.56–57 Then the IPAP is increased until hypopnea, desaturation and respiratory arousals are abolished. In some patients in whom an increase in IPAP is not completely successful or mask leaks/pressure intolerance preclude a higher IPAP, additional increases in EPAP may be tried (Figure 5.5). In patients with hypoventilation or a persistently low arterial oxygen saturation despite upper airway patency, one might try further increases in IPAP to improve oxygenation or increase the tidal volume. An estimation of tidal volume is available on many laboratory diagnostic bilevel devices. The IPAP–EPAP difference is the level of pressure support.
A (a) Flow (L/s)
99
Inspiration 1.0 0 1.0
Pressure (cm H2O)
15 10
(b) B
Inspiration Flow 1.0 (L/s) 0 1.0
Pressure (cm H2O)
15 12.5
Figure 5.5 Bilevel pressure titration. Two sequential tracings (A) and (B) in the same patient. (A) At a bilevel pressure of IPAP = 15, EPAP = 10 cmH2O, apnea was present. After an increase in the EPAP to 12.5 cmH2O apnea resolved. (Adapted from Sanders and Kern.56)
Increases in pressure support provide an inspiratory ‘boost’ and may augment tidal volume. The appearance of central apneas during a positive-pressure titration is sometimes a challenging problem. Central apneas can follow arousals from mask or mouth leaks, arousals related to pressure intolerance, or respiratory-related arousals (persistent high upper airway obstruction). The cause of the arousals may not always be obvious to the technician. In such a case, a trial of slightly lower or higher pressure may be tried, based on the perceived cause of the arousals. If the arousals are secondary to pressure intolerance or leaks, a slightly lower pressure may be indicated. Alternatively, if arousals are secondary to high respiratory effort (RERAs), an increase in pressure may be beneficial. Postarousal central apnea is thought to occur
100
Medical therapy
because the PCO2 level on return to sleep is below the apneic threshold.73 This is especially likely if arousal also triggers brief hyperventilation. Central apneas may also occur in the absence of preceding arousals. The persistence of central apnea after tracheostomy in both non-REM and REM sleep was well described during initial studies of tracheostomy treatment of severe OSA patients.74 The amount of central apneas decreased over time once upper airway stabilization was effected. Non-post-arousal central apneas in patients with severe OSA during CPAP titration may be secondary to a reduction in sleeping PCO2 (with airway stabilization) to a value near the apneic threshold. Aggressive attempts to increase ventilation during sleep, such as a switch to bilevel pressure, may even make the amount of central apneas worse. Positive airway pressure has been demonstrated to be effective in some patients with idiopathic central sleep apnea.75 These non-hypercapnic patients tend to have low daytime PCO2 values. One mechanism by which CPAP induces improvement in this group may be an induction of a mild increase in PCO2.76 Another possible mechanism is prevention of high upper airway resistance, which may trigger central apnea by a negative-pressure reflex76 or by causing arousal. One can increase the level of positive pressure in OSA patients in an attempt to treat central apneas. However, this may not be always be successful or even necessary. For example, brief central apneas can also occur during periods of REM rebound. If they do not cause arousal or desaturation, they are probably best left untreated. One of the most dramatic changes occasionally seen during CPAP titration is the conversion of obstructive or mixed apnea to central apnea of the Cheyne–Stokes type in patients with underlying congestive heart failure.77 The pattern of Cheyne–Stokes central apnea differs
from that of ‘idiopathic central apneas’. In Cheyne–Stokes breathing (CSB), the ventilatory phase between central apneas is typically longer and shows a definite crescendo– decrescendo pattern (Figure 5.6). In patients with OSA and CSB, positive pressure should be titrated to prevent obstruction. Sometimes, further upward titration will prevent CSB, possibly by increasing PCO2. However, more commonly, no level of pressure will abolish CSB, although arterial oxygen saturation and sleep continuity are often improved (decreased
Nasal H22O O Nasal CPAP CPAP 12 12 cm cmH 20 sec Airflow Chest Abdomen SaO2
90%
96% 20 sec
Airflow A A Compressed view of consecutive apneas
Figure 5.6 A central apnea of the Cheyne–Stokes type that appeared during a CPAP titration. At this pressure, obstructive and mixed apneas were eliminated. Higher pressures did not abolish central apneas. A compressed view of several contiguous central apneas shows the crescendo–decrescendo pattern. Note that arousals occurred several breaths after the cessation of apnea (A). In Cheyne–Stokes central apnea, arousal tends to occur at the maximum of ventilatory effort. (Adapted from Berry RB, Sleep Medicine Pearls. Philadelphia; Hanley & Belfus, page 181.)
Positive airway pressure arousals). Based on the experience of investigators who treat pure CSB secondary to congestive heart failure, a reasonable recommendation is to increase the level of positive pressure until obstruction is abolished or to 10–12 cmH2O (whichever is higher). This level of pressure commonly improves cardiac function in many patients and may ultimately reduce CSB.78
Alternative methods of titration and prescription pressure stability over time Because traditional in-laboratory positivepressure titrations are expensive, other methods of determining an optimum pressure have been explored. Hoffstein and developed a prediction colleagues79,80 equation: CPAP = –5.121 + 0.13 ⫻ BMI + 0.16 ⫻ NC + 0.04 ⫻ AHI. This equation incorporates the BMI (BMI = weight in kg/ (height in meters)2), the neck circumference (NC) in centimeters at the cricothyroid membrane, and the AHI. Calculations from this formula lack sufficient accuracy to replace in-laboratory titration. However, the equation may serve as a rough guide. In-home titration by a nurse or spouse has also been attempted, and many patients with respiratory failure undergo titrations in intensive care units (ICUs) with the endpoint to prevent desaturation. When stable, patients can undergo a traditional in-laboratory titration for fine tuning the prescription pressure. As discussed above, auto-titrating units have a built-in algorithm for pressure titration. Therefore, they could be used as a technician ‘extender’ in the sleep laboratory or for unattended titrations in hospital or at home. Studies comparing auto-CPAP titrations with traditional polysomnographic titrations have
101
generally found close agreement in the prescription pressure for moderate to severe patients.60–64 Auto-titrating units with airflow limitation in their algorithm are quite sensitive to milder degrees of airway narrowing and may result in slightly higher pressures than traditional polysomnography performed with thermistors. Of note is the fact that many of the studies comparing auto-titration with traditional titration have been performed in a sleep laboratory. Technicians in many cases made mask adjustments to minimize leaks. In addition, patients with a number of conditions were often excluded. For example, patients with underlying congestive heart failure (and possible CSB), hypoventilation or the overlap syndrome (OSA + chronic obstructive pulmonary disease (COPD)) were often not included. Problems with auto-titrating devices have been described in such patients with cardiopulmonary disease.81 Certainly the autotitrating devices are not designed to treat arterial oxygen desaturation that occurs despite a patent upper airway. In the USA, unattended CPAP titration is either not reimbursed or reimbursed at a lower level. For all of these reasons, unattended auto-CPAP titration cannot be recommended for routine titration of CPAP. The auto-titrating devices might allow a technician to titrate more patients at a time in a laboratory environment. The technician would still be available for reassurance, education, mask adjustment, and recognition of complications. Retitration at home with an auto-titrating device to verify the adequacy of the current prescription pressure might be another potential use for these devices if reimbursement is not an issue. There are a number of other factors complicating the use of auto-titration devices. Units using airway vibration for titration may not work in patients who do not snore or who have
102
Medical therapy
had a uvulopalatopharyngoplasty (UPPP). Some units are not designed to work with all types of humidifiers or masks. In general, auto-titrating
Leak (l/sec) (L/sec)
Pressure (cmH2O)
A (a)
Leak (l/sec) (L/sec)
Pressure (cmH2O)
B (b)
20 8 0 1
0
0
1
2
3
4
5
6
20 8 0 1
0
0
1
2
3 4 5 Hours in study
6
7
Figure 5.7 Auto-CPAP printout table. Each division in the pressure graph represents 4 cm of H2O pressure. Mask pressure and total leak during two AutoSet automatic pressure titration studies. (A) Pressure started at default pressure of 4 cmH2O. There was a brisk rise in pressure approximately 10 min into the study, corresponding to sleep onset. Thereafter, pressure varied between 4 and 10 cmH2O. Recommended pressure was 9 cmH2O. Mask leak remained minimal throughout the study. (B) A period of high mask leak at 5 h into the study was associated with a brief inappropriate rise in pressure, corrected by the subject reseating the mask. Recommended pressure was 10 cmH2O. (Reprinted with permission, Teschler H, Bethon-Jones M, Thompson AB et al. Automated continuous positive airway pressure titration for obstructive sleep apnea syndrome. Am J Respir Crit Care Med 1996;154:734–40.)
devices have problems adapting to large leaks or central apnea. When attended or unattended auto-titration is performed to determine a fixed prescription pressure, it is imperative to view a pressure and leak versus time printout (Figure 5.7). High pressures are delivered in response to leaks and may not be needed with proper mask adjustment. No matter how it is determined, the ‘optimum pressure’ may be influenced over time by a number of factors. Some have suggested that a lower pressure may be required with continuous treatment,82 while others have documented stability over time.83 If a decrease in pressure is required, one explanation may be an increase in upper airway size secondary to decreased edema.84 In a given patient, changes in nasal resistance (colds, allergy) and weight fluctuations could also affect the required pressure. While some have cited that ethanol can increase pressure requirements, two studies have shown that moderate ingestion does not cause a significant increase in required level of pressure.85,86 This is probably because, with CPAP, upper airway muscles are already relaxed. However, ethanol ingestion is still to be discouraged, as intoxicated patients may not apply the mask correctly, remove the mask during the night, or fail to notice mask leaks. If apnea occurs, event duration will be longer, as ethanol increases the arousal threshold to airway occlusion.87
Adjunctive treatments including supplemental oxygen There are times when the optimal level of pressure is not tolerated by the patient, or upper airway patency is not restored at the highest pressure that the blower can produce (morbidly obese patients). At other times, the optimal level of pressure cannot be maintained
Positive airway pressure secondary to intractable mask leaks or leaks through the mouth. In such cases, one may consider the use of adjunctive treatments. One treatment that is often overlooked is the ability of elevation of head of the bed or the side sleeping position to enhance the effectiveness of a given level of CPAP. Neill et al found that the level of pressure needed to maintain upper airway patency was reduced by as much as 5 cmH2O by elevating the head of the bed 30º.88 In obese patients, elevation of the head of the bed may be more effective than the lateral sleeping position. Although not studied systematically, simultaneous treatment with an oral appliance may also reduce the level of positive pressure needed to maintain upper airway patency. Obviously, weight loss can also be a useful adjunctive treatment. Unfortunately, it takes time and, as discussed above, is difficult to maintain. Another potential approach is the augmentation of upper airway muscle activity by pharmacologic means. There is a single case report of enhancement of effectiveness of a given level of CPAP by addition of protriptyline.89 This non-sedating antidepressant may produce an augmentation of upper airway muscle activity;90 however, it causes urinary retention in a high percentage of men. There is some evidence that selective serotonin reuptake inhibitors (SSRIs), such as fluoxetine or paroxetine, may also be effective at increasing upper airway patency in some patients with OSA.90 The possible future use of serotonin-enhancing medications is discussed in Chapter 15. At this time, such pharmacologic adjunctive therapy must be considered experimental. In patients with a low awake PO2 or severe obesity, desaturation may persist even after upper airway patency is effected. This is especially common during REM sleep on initial CPAP titrations, and the degree of desaturation may be severe.91 If a trial of
103
increased CPAP pressure does not help, the addition of supplemental oxygen is one approach. Two other alternatives in this situation are delivery of pressure support via bilevel pressure or the use of volume-cycled ventilation. In our experience, some patients requiring oxygen during the initial CPAP titration with its large REM rebound may be adequately treated with CPAP alone several weeks later. In patients with the overlap syndrome (OSA and COPD) and low awake arterial oxygen saturations, supplemental oxygen is commonly required in addition to positive pressure.92 Oxygen may be added to the circuit either at the mask or at the outflow port of the blower unit. The effective FiO2 for a given liter flow of oxygen depends on the amount of flow from the CPAP device. In devices where the controlled leak is proximal to the mask, a lower flow rate of oxygen may be required if oxygen is added to the mask.35 In general, higher flow rates of oxygen are needed if the total flow from the blower unit is high (high mask or oral leaks).
Benefits of upper airway stabilization Stabilization of the upper airway often results in a large rebound in the amount of slow-wave and REM sleep on the titration night. Virtual elimination of obstructive and mixed apnea, hypopnea, desaturation and RERAs occurs with an optimal pressure level.3,33–36 Patients having such results often report feeling better and less sleepy after a single night of CPAP.93 Indeed, multiple uncontrolled studies have documented that optimal CPAP use is associated with an increase in sleep latency on the multiple sleep latency test (MSLT), although not always into the normal range. A larger increase in the sleep latency on the maintenance
104
Medical therapy
of wakefulness test (MWT) is seen after CPAP treatment.94 Improvement in daytime sleepiness may require more prolonged treatment in some patients.95 A review by Wright et al questioned the scientific evidence for the efficacy of CPAP as a treatment for OSA because of a lack of placebo-controlled studies that documented improved patient outcomes.16 This challenge has been answered by two placebo-controlled trials showing clear improvements in subjective and objective sleepiness as well as the quality of life compared to control groups.6,34 One of the studies used subtherapeutic CPAP (1 cmH2O) as the placebo.34 An improvement in subjective but not objective sleepiness was seen in the group treated with subtherapeutic CPAP. Thus, clinicians taking care of patients should remember that even CPAP may have a ‘placebo’ effect. However, a much larger improvement in both subjective and objective sleepiness was noted in the therapeutic CPAP treatment group. Another study found that patients with mild OSA (AHI 5–15/h) benefited from CPAP treatment more than from an oral placebo.6 Both studies also documented an improvement in mood and quality of life indices. The study of mild patients did report a low hours/night rate of objective compliance with CPAP. Studies comparing CPAP treatment with conservative therapy (weight loss, sleep hygiene) in patients with mild OSA5 and moderate to severe OSA96 have also documented clear advantages to CPAP treatment. Jokic et al found that while patients with positional sleep apnea had acceptable treatment with both position therapy (backpack inducing the side sleep position) and nasal CPAP, a significant fraction of the patients at the end of the study actually preferred CPAP.97 Withdrawal of CPAP for even one night can cause a return of sleepiness.98 Similarly, withdrawal of CPAP for
three nights has been shown to impair the arousal response (increased arousal threshold) to airway occlusion.99 Positive-pressure treatment also results in benefits besides improvements in daytime alertness and mood. In patients with daytime hypercapnia (obesity hypoventilation syndrome or OSA + COPD), adequate treatment is often associated with a reduction in daytime PCO2.100,101 Non-invasive positivepressure treatment may also avoid intubation in patients with OSA and acute hypercapnic respiratory failure.102 Studies of the awake hypercapnic ventilatory response have shown a parallel shift in the ventilation versus PCO2 line with CPAP treatment.103 That is, the slope was unchanged but the ventilation at a given PCO2 was higher. In patients with both OSA and asthma, treatment of OSA may actually improve control of lower airways disease.104 A retrospective study of survival in patients with moderate to severe OSA (apnea index > 20/h) found an improvement in survival on CPAP compared to untreated controls. Thus, while the study was neither prospective nor randomized, it remains some of the best evidence for a survival benefit with treatment in patients with moderate to severe OSA. The reason for an improved survival is not known but may be secondary to multiple detrimental effects of untreated OSA on the progression or consequences of atherosclerotic heart disease, hypertension, or heart failure. A good therapeutic CPAP result typically decreases catecholamine excretion,105 sympathetic activity,106 and nocturnal pulmonary and systemic blood pressure.107,108 Daytime blood pressure may also decrease in some patients.109 Patients with coronary artery or cerebrovascular disease may also benefit from adequate treatment of the OSA. Nasal CPAP reverses OSAinduced increases in fibrinogen110 and platelet
Positive airway pressure
105
Table 5.4 Side-effects and interventions. Positive-pressure side-effects
Interventions
Mask interface Air leaks Conjunctivitis Discomfort
Proper mask fitting Proper mask application (education) Different brand/type of mask Customized mask Alternate between different mask types Nasal prongs/ pillows Tape barrier for skin protection Different headgear Low pressure alarm If snoring on CPAP then increase pressure
Skin breakdown Unintentional mask removal Nasal symptoms Epistaxis 冧 Pain, dryness Congestion/obstruction
Nasal saline Humidification Nasal steroid inhaler Antihistamines (if allergic component) Humidification (heated) Night-time decongestants Full facemasks (oronasal) Nasal ipratropium bromide Antihistamines (if allergic component) Frequent filter changes
Rhinitis/rhinorrhea Mouth symptoms Mouth leaks Mouth dryness
Humidification (prevent increased nasal resistance) Treatment of nasal problems Chin straps (?) Full facemask Lower pressure/bilevel pressure
Pressure problems Pressure intolerance
Difficulty exhaling Snoring on positive pressure Feeling of not getting enough flow Inability to maintain upper airway patency at pressure limit
冧
Miscellaneous problems Machine noise Claustrophobia Questionable compliance Persistent desaturation despite patent upper airway
Ramp Bilevel pressure Auto-titrating device Lower prescription pressure—accept higher AHI Lower pressure + adjunctive measures Weight loss, elevated head of bed, side sleeping position, simultaneous oral appliance (?) Bilevel pressure Raise pressure 1–2 cmH2O Fix high leak if present Bilevel pressure Volume-cycled ventilation Adjunctive treatments Supplemental oxygen Long tubing with machine removed from bedroom Different brand of blower Desensitization Nasal prongs Time meter Downloadable time at pressure information Spouse education Try increase in CPAP 1–2 cmH2O Bilevel pressure Add supplemental oxygen
106
Medical therapy
activation.111 A study of OSA patients with cardiomyopathy demonstrated an improvement in the ejection fraction after successful OSA treatment with nasal CPAP.112 Patients with arrhythmias or heart block may also improve.113 CPAP treatment also reduces nocturnal naturesis and typically reduces episodes of nocturia.114 The mechanism may be a reduction in atrial natriuretic peptide (ANP) secretion, although other factors may also be involved.
Side-effects of positive-pressure treatment Several studies have enumerated the many side-effects with positive-pressure treatment.35,36,115,116 If left untreated, side-effects from positive airway pressure may cause a lower chance of acceptance and lower rates of compliance.117 Side-effects and possible interventions are listed in Table 5.4. Prevention and/or elimination of side-effects at the introduction of CPAP appears to be very important. Patients complying over the first 1–3 months tend to continue to accept positive-pressure treatment.118,119 Weaver and coworkers found that a difference in the pattern of use by compliant and non-compliant patients is noted as early as 4 days of treatment.120 Many sideeffects are secondary to the mask interface. In one study, intolerance of the mask was the most common reason for discontinuing CPAP treatment.119 Obtaining an adequate mask fit may require trials of several different brands and types of masks. While most companies make a few sizes of masks, there are many sizes of faces. Obtaining an adequate seal at the bridge of the nose is an especially difficult problem. Adequate mask positioning is also essential, as is elimination of overtightening of head straps. Often, moving the mask up or
down slightly will produce a better seal than further tightening. Poor mask fit leads to leaks which are both uncomfortable (especially into the eyes) and may result in an inadequate pressure. Conjunctivitis has been described during CPAP use.121 Overtightening of head straps can result in severe skin abrasion, especially on the bridge of the nose (‘CPAP divot’). Turning in bed can also change the mask position, resulting in loss of mask seal. Improvements in mask material and flexibility in the mask–hose connection have been used in an attempt to reduce these problems. Swivel arms to allow hose movement with minimal mask movement have also been introduced to approach this problem. Some companies offer thermolabile materials that, when heated, conform to the shape of the face. Other masks utilize thin material that balloons out against the face under pressure. Nasal prongs (nasal pillows) can sometimes provide a useful alternative for patients unable to get a good seal around the nasal bridge. Adequate care of masks (cleaning) and replacement of masks when old (and less flexible) is also necessary. Nasal symptoms, including congestion, rhinorrhea, pain, dryness, and epistaxis, are all potential problems with positive-pressure treatment. Many OSA patients have underlying nasal congestion that may be worsened by treatment. Nasal congestion may make breathing through the nose uncomfortable and result in oral breathing (leaks). In theory, positive pressure can be applied nasally, because the palate moves forward against the back of the tongue, sealing off the oral passage (Figure 5.2). However, if an oral leak does occur, this removes humidity from the system and can lead to nasal dryness. This mucosal dryness further increases nasal bloodflow (and resistance), leading to even higher mouth leaks.122,123 Nasal congestion may be treated with nasal steroid inhalers, antihistamines (if
Positive airway pressure an allergic component is present), and, as a last resort, bedtime decongestants. The addition of humidification can prevent nasal dryness and pain and may also prevent an escalation of mouth leaks in some patients.123,124 While cold passover humidification may reduce mild symptoms of dryness in some patients, heated humidification is usually required if severe nasal symptoms or mouth leaks occur. Massie et al demonstrated that heated humidification improves compliance, and both heated and passover humidification improved satisfaction with CPAP.124 A full facemask may also prevent a loss of humidity from mouth leaks. In some patients with intractable nasal congestion, a full facemask may be needed. This is especially useful during initial inlaboratory titrations that would otherwise have to be aborted51–53 because of severe nasal obstruction. After intensive treatment of nasal problems and addition of humidity, some patients can later be switched back to a nasal mask. Until recently, the types of commercially available full facemask were limited. Several better-fitting alternatives are now available. Some patients develop rhinorrhea during CPAP treatment or immediately following cessation of treatment. This is usually controlled with intranasal ipratropium bromide. Mouth leaks can be a severe problem during the initial CPAP titration or with home use of CPAP. They may awaken the patient or prevent maintenance of airway patency. During in-laboratory titration, most diagnostic units provide an estimate of the total leak. If the patient is observed to have an open mouth during episodes of high leaks, a mouth leak is obvious. On the polysomnographic tracings, one often sees normal chest and abdominal movements with a low and erratic nasal flow signal. Mouth leaks should always
107
be suspected if patients complain of severe mouth dryness during home use. While chin straps may be tried, their efficacy is probably marginal. Treatment of nasal congestion may improve mouth leaks by lowering nasal resistance. In some patients, adding heated humidification can minimize mouth leaks, as noted above. Full facemasks are another approach. In individual patients, using a slightly lower pressure or switching to bilevel pressure, which allows maintenance of airway patency with a lower pressure in exhalation, may also help control mouth leaks. One study suggested that patients who have undergone a UPPP before CPAP treatment are more likely to develop mouth leaks.125 This is presumably secondary to the defect in the palate. Machine noise was once a common problem, but newer models are much quieter. One could recommend longer tubing and removal of the blower unit from the bedroom. Other side-effects are the noise and discomfort from the stream of air leaving the controlled leak in the mask or mask–hose interface. This can sometimes also bother the bedmate. Again, recent improvements in blower design have attempted to minimize this problem. Some patients also ‘unconsciously’ remove the mask during the night. A few units now have low-pressure alarms. Intolerance to the level of positive pressure is also a common side-effect, especially at higher treatment pressures. There are several approaches to handle the problem. Most machines have a ‘ramp system’, in which the pressure is slowly increased over 5–30 min to the prescription pressure.36,51 While this approach seems reasonable, no study has validated the usefulness of the ramp alternative. Another approach is to utilize bilevel pressure. A third approach is to use adjunctive treatments that are outlined above. These may reduce the required level of positive pressure.
108
Medical therapy
A fourth approach is to try an auto-titrating CPAP device. This should allow airway stabilization with a lower mean pressure for the entire night. A fifth approach is to settle for a less than optimal prescription pressure. There is some evidence that with prolonged use of CPAP there may be a reduction in the pressure needed to maintain upper airway patency. One must also remember that if positive pressure fails, the other therapeutic alternatives may not be able to equal the efficacy of a less than optimal CPAP pressure. Claustrophobia is an especially difficult side-effect to treat. An occasional patient will respond to nasal prongs. Others may need desensitization to the mask and CPAP pressure during the day.126 While never studied systematically some laboratories have even used anxiolytics during the initial CPAP trial in non-hypercapnic patients. In addition, a few patients do not tolerate a low initial ramp pressure. They seem to do better with no ramp or an increase in the initial ramp pressure. We have recently seen two patients with the sudden onset of claustrophobia after being on CPAP for some time. In one case, the blower unit made noise but never reached the prescription pressure. The other patient had decided to remove the controlled leak device from his system and was rebreathing CO2.
Acceptance and compliance Acceptance of positive pressure implies that the patient is willing to use this treatment. Compliance, also termed adherence, means that the patient will use the device nightly for a sufficient time to obtain a benefit. Acceptance of a positive-pressure titration depends on educating the patient about the need for treatment and the lack of other treatments of equivalent efficacy. Such education is not
likely to be effective in the middle of the night. The second major factor in increasing acceptance is to minimize side-effects on the positive-pressure titration night. Careful mask fitting, the use of humidification if mucosal dryness or a mouth leak is prominent, pretreatment of nasal congestion, and slow upward titration of pressure, are strategies that can be tried to increase acceptance. Bilevel pressure may also be tried for patients requiring high pressures. Some patients will request a termination of CPAP titration during a split study, but will accept a repeat full-night CPAP titration after discussion of alternatives with a physician. Overall, up to 5–15% of patients will not accept or tolerate a CPAP titration. Other patients will not accept positive pressure after their experience with CPAP during titration. In one study, up to 30% of patients either did not accept CPAP or discontinued its use.119 McArdle et al found that, at 5 years, 68% of patients were still using their CPAP. Patients who were compliant in the first 3 months were more likely to continue to use positive pressure on a long-term basis.118 Numerous studies have addressed compliance with positive-pressure treatment. Initial studies of self-reported use found 60–80% compliance with CPAP treatment.115,116 Subsequent studies have showed that objectively measured compliance is often significantly less than reported compliance.127,128 In one study, only 46% of patients used their CPAP for more than 70% of the days and more than 4 h/day.127 Thus, obtaining objective compliance data is essential in any outcomes study of positive-pressure treatment. The discouraging early objective data sparked interest in finding methods to increase compliance. A European cooperative study found that 79% of patients met objective compliance criteria (> 4.0 h of nightly use at pressure on 70% of days) over the initial 3 months of treatment.129 Of note is
Positive airway pressure the fact that all centers used three nights of inhospital acclimatization to CPAP and aggressive early treatment of problems. Patients were seen monthly, and compliance as well as the benefits of treatment were discussed. The somewhat higher short-term compliance in this study suggests that intensive interventions can result in better compliance. To address this question more systematically, Hoy et al prospectively compared intensive support and standard support of patients being started on CPAP. Intensive support improved mean objective nightly CPAP use over 6 months by about 1.5 h.130 Intensive support included three nights of CPAP use in the hospital, involvement of the patient’s spouse in all education, and home visits by nurses. Another study found that weekly telephone calls discussing problems and simple interventions encouraging compliance were more effective131 than standard low-level contact. Possible interventions to improve compliance are listed in Table 5.5. Patients with better compliance would be assumed to have better control of their daytime sleepiness. However, the minimum level of compliance needed for reasonable control of symptoms may vary between patients. For example, in the above study of intensive versus standard support, while the mean hourly compliance differed, the sleep latency on the MWT did not (both were in the normal range).130 While most positive-pressure devices have time meters, many modern devices allow downloading of more detailed compliance information. They can show in detail the pattern of use, including time at pressure. In Figure 5.8, a daily compliance record shows that the patient does not use his CPAP on weekends. The measurement of time at pressure might be more accurate for determining meaningful compliance than simple run
109
Table 5.5 Methods to enhance acceptance/compliance. 1.
2. 3. 4. 5. 6. 7. 8. 9. 10.
Intensive education about importance of treatment and treatment alternatives before sleep study Careful mask fitting, testing for leaks/comfort before sleep study Pretreatment of nasal congestion if present Availability/routine use of humidification Involvement of spouse in education/ CPAP training Early interventions for sideeffects/discomforts Frequent contact with support personnel in first few weeks Monthly contact with physician during start of treatment Objective compliance monitoring–time meters, download usage Change mode of pressure delivery/prescription pressure as needed
time meters. However, the above European compliance study found compliance by hour meter and time at pressure to be similar.129 Evidently, most patients do not take the time to run their machines simply to appear compliant. In any case, objective compliance monitoring allows sleep physicians to intervene, encourages patient responsibility, and prevents needless studies to evaluate patients with persistent sleepiness who are not being honest about their level of compliance.
Modes of positive-pressure delivery and compliance There appears to be no firm evidence that bilevel pressure will substantially increase the
110
Medical therapy Blwr. time 02h 56m 03h 30m 04h 10m 04h 00m 06h 18m 02h 12m 07h 21m 07h 00m 08h 05m 02h 17m 04h 24m 07h 03m 06h 25m 07h 40m 05h 43m 07h 18m 07h 20m 12 14 16 18 20 22 24 2 4 6 8 10 12 Time
Graph based on 04/29/99 – 05/18/99 (20 days) (93.7 blwr hrs) 100 90 80 Percent of days
Thu Fri Sat Sun 05/03/99 Tue Wed Thu Fri Sat Sun 05/10/99 Tue Wed Thu Fri Sat Sun 05/17/99 Tue
70 60 50 40 30 20 10 0 0
1
2
3
4
5
6
7
8
Device usage (hours)
Figure 5.8 Compliance data for a patient who claimed that he used positive pressure every night. On the left, daily time at pressure information is shown. The red bars denote less than the threshold compliance level (here set at 4 h per night). The green bars denote higher than the threshold level of compliance. Note that the patient sometimes skipped entire nights of CPAP use. The graph on the right shows that the patient used his CPAP for 4 h or more on about 65% of the nights during the time period analyzed. (Encore compliance program, Respironics.)
overall rate of compliance with positive pressure in unselected patients.57 However, most physicians have found that some individual patients will accept and comply better with this form of positive pressure. For example, some patients with COPD find bilevel pressure much more comfortable. Perhaps the lack of a tremendous improvement in compliance in many patients with bilevel pressure is not surprising, as many of the side-effects with positive pressure may also occur at relatively low pressures. One would also suspect that
patients in whom the IPAP–EPAP difference was small would not be able to tell much difference from traditional fixed-pressure CPAP. A few studies have showed a modest advantage in compliance with auto-titrating devices.62,63 Konermann et al randomized patients to fixed-level CPAP or auto-titrating CPAP after an in-laboratory CPAP titration with the appropriate device. They excluded patients requiring more than 14 cmH2O. A significant advantage was found in the
Positive airway pressure nights-per-week that auto-CPAP was utilized (5.7 versus 6.5), but not the mean hours per night. Interestingly, the mean mask pressure in the auto-titrating CPAP group differed from that in the fixed CPAP group by only about 1.6 cmH2O. Perhaps this small difference explains why larger differences in compliance were not present. Alternatively, patients with positional apnea (events substantially reduced in the lateral sleep position) or events only during REM sleep might have a substantially lower mean nightly pressure when using an auto-titrating device. At the present time, the added expense (typically $500 or more) has precluded routine use of these devices, despite some evidence for a very modest increase in compliance. However, in individual patients with poor tolerance or compliance with traditional CPAP, auto-adjusting units may certainly be worth trying.
Patients still sleepy on positivepressure treatment Patients who report a deterioration in daytime alertness while on CPAP present a challenging problem. If the patient’s bedmate reports any snoring or apnea while the patient uses positive pressure, this is an important clue that the prescription pressure is too low. An appreciable weight gain may also suggest that the prescription pressure may need to be raised. Other possibilities, such as mask leak, mouth leak, poor compliance, or another sleep disorder (periodic limb movements in sleep or narcolepsy), must be considered. Unfortunately, patient reports of compliance are unreliable. Thus, the first step is to document compliance with an objective method. If compliance appears adequate, another approach is to utilize an auto-titrating unit for one or several nights to check the required
111
pressure. An empirical increase in the prescription pressure by a few cmH2O may also be tried if an inadequate-pressure problem is suspected (recent weight gain, etc.). A repeat sleep study–pressure titration is indicated if these interventions do not prove informative and sleepiness persists. If narcolepsy is suspected, one approach is to perform a nighttime study at the prescription pressure (documenting good sleep) and a MSLT on the following day while using CPAP.132 An MSLT showing a short sleep latency and two or more REM periods despite good nocturnal sleep supports a diagnosis of narcolepsy (in addition to OSA).
Positive airway pressure treatment in the future One can expect that technological innovations will continue to improve blower units and mask interfaces. The price of auto-titrating CPAP will undoubtedly be reduced and they will probably be more widely used for treatment. One can also expect that the diagnostic capabilities of machines will increase. Hopefully, governmental agencies will require that all blower units have, at a minimum, a run time clock for checking compliance. On the other hand, a rigid standard for the mean hourly usage to qualify for reimbursement may be a detrimental intrusion. The amount of usage needed to obtain a benefit may vary between patients. In addition, we do not know the minimum usage necessary to reverse or avoid sequelae. It is also obvious from objective compliance studies that more effort needs to be directed to optimizing therapy during the early nights of CPAP use. In the USA, the physician reading the sleep study, the physician directing patient care (often a primary care physician), and the home healthcare
112
Medical therapy
company providing positive-pressure device delivery and follow-up, are often separated by distance and organizational units. Communication is often suboptimal and treatment poorly coordinated. As practice often follows reimbursement in the USA, funding agencies will hopefully require more attention to outcomes, compliance, and the optimal coordinated delivery of positive-pressure treatment.
References 1. Guilleminault C, Dement W. Sleep apnea syndromes and related disorders. In Williams R, Karacan I, Moore C, eds, Sleep Disorders: Diagnosis and Treatment. New York: Wiley, 1988; 47–71. 2. Strollo PJ, Rogers RM. Obstructive sleep apnea. N Engl J Med 1996;334:99–104. 3. Young T, Palta M, Dempsey J, Skatrud J, Weber S, Badr S. The occurrence of sleepdisordered breathing among middle aged adults. N Engl J Med 1993;328:1230–5. 4. Guilleminault C, Stoohs R, Clerk A, Cetel M, Saltros P. A cause of excessive daytime sleepiness: the upper airway resistance syndrome. Chest 1993;104:781–7. 5. Redline S, Adams N, Strauss ME, Roebuck T, Winters M, Rosenberg C. Improvement of mild sleep-disordered breathing with CPAP compared with conservative therapy. Am J Respir Crit Care Med 1998;157:858–65. 6. Engleman HM, Kingshott RN, Wraith PK, MacKay TW, Deary IJ, Douglas NJ. Randomized placebo controlled crossover trial of continuous positive airway pressure for mild sleep apnea. Am J Respir Crit Care Med 1999;159:461–7. 7. Gould GA, Whyte KF, Rhind GB et al. The sleep hypopnea syndrome. Am Rev Respir Dis 1988;137:895–8.
8. Berry RB, Gleeson K. Respiratory arousal from sleep: mechanisms and significance. Sleep 1997;20:654–75. 9. Bonnet MH. Performance and sleepiness as a function of frequency and placement of sleep disruption. Psychophysiology 1986;23:263–71. 10. American Academy of Sleep Medicine Task Force. Sleep related breathing disorders in adults: recommendations for syndrome definition and measurement techniques in clinical research. Sleep 1999;22:667–89. 11. Loube DI, Gay PC, Strohl KP, Pack AI, White DP, Collop NA. Indications for positive airway pressure treatment of adult obstructive sleep apnea patients. A consensus statement. Chest 1999;115:863–6. 12. Hosselet J, Norman RC, Ayappa I, Rapoport DM. Detection of flow limitation with nasal cannula/pressure transducer system. Am J Respir Crit Care Med 1998;157:1461–7. 13. Martin SE, Wraith PK, Feary IJ, Douglas NJ. The effect of nonvisible sleep fragmentation on daytime function. Am J Respir Crit Care Med 1997;155:1596–601. 14. Mathur R, Douglas NJ. Frequency of EEG arousals from nocturnal sleep in normal subjects. Sleep 1995;18:330–3. 15. He J, Kryger MH, Zorick FJ, Conway W, Roth T. Mortality and apnea index in obstructive sleep apnea. Chest 1988;94:9–14. 16. Wright J, Johns R, Wart I, Melville A, Sheldon T. Health effects of obstructive sleep apnoea and the effectiveness of continuous positive airways pressure: a systematic review of the research evidence. BMJ 1997;314:851–60. 17. Shahar E, Whitney CW, Redline S, et al. Sleep-disordered breathing and cardiovascular disease: cross-sectional results of the Sleep Heart Health Study. Am J Respir Crit Care Med 2001;163:19–25. 18. Mortimore IL, Marshall I, Wraith PK, Selar RJ, Douglas NJ. Neck and total body fat
References
19.
20.
21.
22.
23. 24.
25.
26.
27.
28.
29.
deposition in nonobese and obese patients with sleep apnea compared with that in control subjects. Am J Respir Crit Care Med 1998;157:280–3. Strobel RJ, Rosen RC. Obesity and weight loss in obstructive sleep apnea: a critical review. Sleep 1996;19:104–15. Smith PL, Gold AR, Meyers DA, Haponik EF, Bleecker ER. Weight loss in mildly to moderately obese patients with obstructive sleep apnea. Ann Intern Med 1985;103:850–5. Shelton KE, Woodson H, Gay S, Suratt PM. Pharyngeal fat in obstructive sleep apnea. Am Rev Respir Dis 1993;148:462–6. Horner RL, Mohiaddin RH, Lowell D et al. Sites and sizes of fat deposits around the pharynx in obese patients with obstructive sleep apnea and weight matched controls. Eur Respir J 1989;2:613–22. Schwab RJ. Upper airway imaging. Clin Chest Med 1998;19:33–54. Hoffstein V, Zamel N, Phillipson EA. Lung volume dependence of cross-sectional area in patients with obstructive sleep apnea. Am Rev Respir Dis 1984;130:175–8. Van de Graaff WB. Thoracic influences on upper airway patency. J Appl Physiol 1988;65:2124–31. Rubinstein I, Colapinto N, Rotstein LE, Brown IG, Hoffstein V. Improvement in upper airway function after weight loss in patients with obstructive sleep apnea. Am Rev Respir Dis 1988;138:1192–5. Schwartz AR, Gold AR, Schubert N et al. Effect of weight loss on upper airway collapsibility in obstructive sleep apnea. Am Rev Respir Dis 1991;144:494–8. Harman E, Wynne JW, Block AJ. The effect of weight loss on sleep-disordered breathing and oxygen desaturation in morbidly obese men. Chest 1982;82:291–4. Kansanen M, Vanninen E, Tuunainen A et al. The effect of a very low-calorie dietinduced weight loss on the severity of obstructive sleep apnea. Clin Physiol 1998;18:377–85.
113
30. Sampol G, Munoz X, Sagales MT et al. Long-term efficacy of dietary weight loss in sleep apnea/hypopnea syndrome. Eur Respir J 1998;123:1156–9. 31. Pillar G, Peled R, Lavie P. Recurrence of sleep apnea without concomitant weight increase 7.5 years after weight reduction surgery. Chest 1994;106:1702–4. 32. Noseda A, Kempenaers C, Kerkhofs M, Houben J, Linkowksi P. Sleep apnea after 1 year domiciliary nasal-continuous positive airway pressure and attempted weight reduction. Chest 1996;109:138–43. 33. Sullivan CE, Issa FG, Berthon-Jones M, Eves L. Reversal of obstructive sleep apnoea by continuous positive airway pressure applied through the nares. Lancet 1981;1:862–5. 34. Jenkinson C, Davies RJO, Mullins R, Stradling JR. Comparison of therapeutic and subtherapeutic nasal continuous positive airway pressure for obstructive sleep apnea: a randomised prospective parallel trial. Lancet 1999;353:2100–5. 35. ATS Statement. Indications and standards of use of nasal continuous positive airway pressure (CPAP) in sleep apnea syndromes. Am J Respir Crit Care Med 1994;150:1738–45. 36. Strollo PJ Jr, Sanders MH, Atwood CW. Positive pressure therapy. Clin Chest Med 1998;19:55–68. 37. Berry RB, Block AJ. Positive nasal airway pressure eliminated snoring as well as obstructive sleep apnea. Chest 1984;85:15–20. 38. Rauscher H, Formanerk D, Zick A. Nasal continuous positive airway pressure for nonapneic snoring? Chest 1995;107:58–61. 39. Alex CG, Aronson RM, Onal E, Lopata M. Effects of continuous positive airway pressure on upper airway and respiratory muscle activity. J Appl Physiol 1987;62:2026–30. 40. Strohl KP, Redline S. Nasal CPAP therapy, upper airway muscle activation and obstructive sleep apnea. Am Rev Respir Dis 1986;134:555–8.
114
Medical therapy
41. Mezzanotte WS, Tangel DJ, White DP. Waking genioglossal electromyogram in sleep apnea patients versus normal controls (a neuromuscular compensatory mechanism). J Clin Invest 1992;89:1571–9. 42. Kuna ST, Bedi DG, Ryckman C. Effect of nasal airway positive pressure on upper airway size and configuration. Am Rev Respir Dis 1988;138:969–75. 43. Abbey NC, Block AJ, Green D, Mancuso A, Hellard DW. Measurement of pharyngeal volume by digitized magnetic resonance imaging. Effect of nasal continuous positive airway pressure. Am Rev Respir Dis 1989;140:717–23. 44. Schwab RJ, Pack AI, Gupta KB et al. Upper airway and soft tissue structural changes influences by CPAP in normal subjects. Am J Respir Crit Care Med 1996;154:1106–16. 45 Schwab RJ, Gefter WB, Hoffman EA, Gupta KB, Pack AI. Dynamic upper airway imaging during awake respiration in normal subjects and patients with sleep-disordered breathing. Am Rev Respir Dis 1993;148:1385–400. 46. Mahadevia AK, Onal E, Lopata M. Effects of expiratory positive airway pressure on sleep-induced respiratory abnormalities in patients with hypersomnia sleep apnea syndrome. Am Rev Respir Dis 1983;128:708–11. 47. Series F, Cormier Y, Lampron N, LaForge J. Increasing functional residual capacity may reverse obstructive sleep apnea. Sleep 1988;11:349–53. 48. Abbey NC, Cooper KR, Kwentus JA. Benefit of nasal CPAP in obstructive sleep apnea is due to positive pharyngeal pressure. Sleep 1989;12:420–2. 49. Series F, Cormier Y, Couture J, Desmeules M. Changes in upper airway resistance with lung inflation and positive airway pressure. J Appl Physiol 1990;68:1075–9. 50. Montserrat JM, Ballester E, Olivi H. Time course of stepwise CPAP titration. Am J Respir Crit Care Med 1995;152:1854–9.
51. Rapoport DM. Methods to stabilize the upper airway using positive pressure. Sleep 1996;19:S123–30. 52. Sanders MH. Nasal CPAP effect on patterns of sleep apnea. Chest 1984;86:839–44. 53. Prosise GL, Berry RB. Oral–nasal continuous positive airway pressure as a treatment for obstructive sleep apnea. Chest 1994;106:180–6. 54. Sanders MH, Kern NB, Stiller RA, Strollo PJ Jr, Martin TJ, Atwood CW Jr. CPAP therapy via oronasal mask for obstructive sleep apnea. Chest 1994;106:774–9. 55. Mortimore IL, Whittle AT, Douglas NJ. Comparison of nose and face mask CPAP therapy for sleep apnea. Thorax 1998;53:290–2. 56. Sanders MH, Kern N. Obstructive sleep apnea treated by independently adjusted inspiratory and expiratory positive airway pressures via nasal mask. Chest 1990;98:317–24. 57. Claman DM, Piper A, Sanders M. Nocturnal noninvasive positive pressure ventilatory assistance. Chest 1996;110:1581–8. 58. Reeves-Hoché MK, Hudgel DW, Meck R, Whitteman R, Ross A, Zwillich CW. Continuous versus bilevel positive airway pressure for obstructive sleep apnea. Am J Respir Crit Care Med 1995;151:443–9. 59. Loube DI. Technologic advances in the treatment of obstructive sleep apnea syndrome. Chest 1999;116:1426–33. 60. Teschler H, Berthon-Jones M. Intelligent CPAP systems: clinical experience. Thorax 1998;53:S49–54. 61. Meurice JC, Marc I, Series F. Efficacy of auto-CPAP in the treatment of obstructive sleep apnea/hypopnea syndrome. Am J Respir Crit Care Med 1996;153:794–8. 62. Konermann M, Sanner BM, Vyleta M et al. Use of conventional and self-adjusting nasal continuous positive airway pressure for treatment of severe obstructive sleep apnea syndrome. Chest 1998;113:714–18.
References 63. Stradling JR, Barbour C, Pitson DJ, Davies RJ. Automatic nasal continuous positive airway pressure titration in the laboratory: patient outcomes. Thorax 1996;53:72–5. 64. Lloberes P, Ballester E, Montserrat JM et al. Comparison of manual and automatic CPAP titration in patients with sleep apnea/hypopnea syndrome. Am J Respir Crit Care Med 1996;154:1755–8. 65. Piper AJ, Sullivan CE. Effects of short-term NIPPV in the treatment of patients with severe obstructive sleep apnea and hypercapnia. Chest 1994;105:434–40. 66. Sanders MH, Kern NB, Costantino JP et al. Adequacy of prescribing positive airway pressure therapy by mask for sleep apnea on the basis of a partial-night trial. Am Rev Respir Dis 1993;147:1169–74. 67. Yamashiro Y, Kryger MH. CPAP titration for sleep apnea using a split night protocol. Chest 1995;107:62–6. 68. Fleury B, Rakotonanahary D, Tehindrazanarivelo AD, Hausser-Hauw C, Lebeau B. Long-term compliance to continuous positive airway pressure therapy (nCPAP) setup during a split-night polysomnography. Sleep 1994;17:512–15. 69. Oksenberg A, Silverberg DS, Arons E, Radwan H. The sleep supine position has a major effect on optimal nasal continuous positive airway pressure. Chest 1999;116:1000–6. 70. Condos R, Norman RG, Krishnasamy I, Peduzzi N, Goldring RM, Rapoport DM. Flow limitation as a noninvasive assessment of residual upper-airway resistance during continuous positive airway pressure therapy of obstructive sleep apnea. Am J Respir Crit Care Med 1994;150:475–80. 71. Badia JR, Farre R, Kimoff RJ et al. Clinical application of the forced oscillation technique for CPAP titration in the sleep apnea/hypopnea syndrome. Am J Respir Crit Care Med 1999;160:1550–4. 72. Meurice JC, Paquereau J, Denjean A, Patte F, Series F. Influence of correction of flow
73.
74.
75.
76.
77.
78.
79.
80.
81.
82.
83.
115
limitation on continuous positive airway pressure efficiency in sleep apnea/hypopnea syndrome. Eur Respir J 1998;11:1121–7. Dempsey JA, Skatrud JB. A sleep induced apneic threshold and it consequences. Am Rev Respir Dis 1986;133:1163–70. Guilleminault C, Cummiskey J. Progressive improvement of apnea index and ventilatory response to CO2 after tracheostomy in obstructive sleep apnea syndrome. Am Rev Respir Dis 1982:126:14–20. Issa FG, Sullivan CE. Reversal of central sleep apnea using nasal CPAP. Chest 1986;90:165–71. Xie A, Rankin F, Rutherford R, Bradley TD. Effects of inhaled CO2 and added dead space on idiopathic central sleep apnea. J Appl Physiol 1997;82:918–26. Dowdell WT, Javaheri S, McGinnis W. Cheyne–Stokes respiration presenting as sleep apnea syndrome. Am Rev Respir Dis 1990;141:871–9. Naugthon MT, Bradley TW. Sleep apnea in congestive heart failure. Clin Chest Med 1998;19:99–113. Hoffstein V, Mateika S. Predicting nasal continuous positive airway pressure. Am J Respir Crit Care Med 1994;150:486–8. Miljeteig H, Hoffstein V. Determinants of continuous positive airway pressure for treatment of obstructive sleep apnea. Am Rev Respir Dis 1993;147:1526–30. Juhasz J, Schillen J, UrbigKeit A, Ploch T, Penzel T, Peter JH. Unattended continuous positive pressure titration: clinical relevance and cardiorespiratory hazards of the method. Am J Respir Crit Care Med 1996;154:359–65. Jokic R, Klimaszewski A, Sridhar G, Fitzpatrick MF. Continuous positive airway pressure requirement during the first month of treatment in patients with severe obstructive sleep apnea. Chest 1998;114:1061–9. Teschler H, Farhat AA, Exner V, Konietzko
116
84.
85.
86.
87.
88.
89.
90.
91.
92.
Medical therapy N, Berthon-Jones M. AutoSet nasal CPAP titration: constancy of pressure, compliance and effectiveness at 8 month follow-up. Eur Respir J 1997;10:2073–8. Mortimore IL, Kochhar P, Douglas NJ. Effect of chronic continuous positive airway pressure (CPAP) therapy on upper airway size in patients with sleep apnoea/hypopnea syndrome. Thorax 1996;51:190–2. Berry RB, Desa MM, Light RW. Effect of ethanol on the efficacy of nasal continuous positive airway pressure as a treatment for obstructive sleep apnea. Chest 1991;99:339–43. Teschler H, Berthon-Jones M, Wessendorf T, Meyer HJ, Konietzko N. Influence of moderate alcohol consumption on obstructive sleep apnoea with and without AutoSet nasal CPAP therapy. Eur Respir J 1996;9:2371–7. Berry RB, Bonnet MH, Light RW. Effect of ethanol on the arousal response to airway occlusion during sleep in normal subjects. Am Rev Respir Dis 1992;145:445–52. Neill AM, Angus SM, Sajkov D, McEvoy RD. Effects of sleep posture on upper airway stability in patients with obstructive sleep apnea. Am J Respir Crit Care Med 1997;155:199–204. Nino-Murcia G, Bliwise D, Keenan SR, Feibusch K. Treatment of obstructive sleep apnea with CPAP and protriptyline. Chest 1988;94:1314–15. Hudgel DW, Thanakitcharu S. Pharmacologic treatment of sleep-disordered breathing. Am J Respir Crit Care Med 1998;158:691–9. Krieger J, Weitzenblum E, Monassier JP, Stoeckel C, Kurtz D. Dangerous hypoxemia during continuous positive airway pressure treatment of obstructive sleep apnoea. Lancet 1983;17(2):1429–30. Sampol G, Sagalés MT, Roca A et al. Nasal continuous positive airway pressure with supplemental oxygen in coexistent sleep apnea–hypopnea syndrome and severe
93.
94.
95.
96.
97.
98.
99.
100.
101.
102.
chronic obstructive pulmonary disease. Eur Respir J 1996;9:111–16. Rajagopal KR, Bennet LL, Dillard TA, Tellis CJ, Tenhold ME. Overnight nasal CPAP improves hypersomnolence in sleep apnea. Chest 1986;90:172–6. Poceta JS, Timms RM, Jeong D, Ho S, Erman MK, Mitler MM. Maintenance of wakefulness test in obstructive sleep apnea syndrome. Chest 1992;101:893–7. Meurice JC, Paquereau J, Neau JP et al. Long-term evolution of daytime somnolence in patients with sleep apnea/hypopnea syndrome treated by continuous positive airway pressure. Sleep 1997;20:1162–6. Ballester E, Badia JR, Hernandex L et al. Evidence of the effectiveness of continuous positive airway pressure in the treatment of sleep apnea/hypopnea syndrome. Am J Respir Crit Care Med 1999;159:495–501. Jokic R, Klimaszewski A, Crossley M, Sridhar G, Fitzpatrick MF. Positional treatment vs continuous positive airway pressure in patients with positional obstructive sleep apnea syndrome. Chest 1999;115:771–81. Kribbs N, Pack AK, Kline LR et al. Effects of one night without nasal CPAP treatment on sleep and sleepiness in patients with obstructive sleep apnea. Am Rev Respir Dis 1993;147:1162–8. Berry RB, Kouchi K, Der DE, Dickel MJ, Light RW. Sleep apnea impairs the arousal response to airway occlusion. Chest 1996;109:1490–6. Sullivan CE, Berthon-Jones M, Issa FG. Remission of severe obesity–hypoventilation syndrome after short-term treatment during sleep with nasal continuous positive airway pressure. Am Rev Respir Dis 1983;128:177–81. Rapoport DM, Garay SM, Epstein H, Goldring RM. Hypercapnia in the obstructive sleep apnea syndrome. Chest 1986;89:627–35. Shivaram U, Cash ME, Beal A. Nasal
References
103.
104.
105.
106.
107.
108.
109.
110.
111.
continuous positive airway pressure in decompensated hypercapnic respiratory failure as a complication of sleep apnea. Chest 1993;104:770–4. Berthon-Jones M, Sullivan CE. Time course of change in ventilatory response to CO2 with long-term CPAP therapy for obstructive sleep apnea. Am Rev Respir Dis 1987;135:144–7. Chan CS, Woolcock AJ, Sullivan CE. Nocturnal asthma: role of snoring and obstructive sleep apnea. Am Rev Respir Dis 1988;137:1502–4. Hedner J, Darpo B, Ejnell H, Carlson J, Caidahl K. Reduction in sympathetic activity after long-term CPAP treatment in sleep apnoea: cardiovascular implications. Eur Respir J 1995;8:222–9. Waradekar NV, Sinoway LI, Zwillich CW, Leuenberger UA. Influence of treatment on muscle sympathetic nerve activity in sleep apnea. Am J Respir Crit Care Med 1996;153:1333–8. Akashiba T, Minemura H, Yamamoto H, Kosaka N, Saito O, Horie T. Nasal continuous positive airway pressure changes blood pressure ‘non-dippers’ to ‘dippers’ in patients with obstructive sleep apnea. Sleep 1999;22:849–53. Sforza E, Krieger J, Weitzenblum E, Apprill M, Lampert E, Ratamaharo J. Long term effects of treatment with nasal continuous positive airway pressure on daytime lung function and hemodynamics in patients with obstructive sleep apnea. Am Rev Respir Dis 1990;141:866–70. Fletcher EC. Can the treatment of sleep apnea syndrome prevent the cardiovascular consequences? Sleep 1996;19:S67–70. Chin K, Ohui M, Kita H et al. Effects of NCPAP therapy on fibrinogen levels in obstructive sleep apnea syndrome. Am J Respir Crit Care Med 1996;153: 1972–6. Bokinsky G, Miller M, Ault K, Husband P, Mithchell J. Spontaneous platelet activation
112.
113.
114.
115.
116.
117.
118.
119.
117
and aggregation during obstructive sleep apnea and its response to therapy with nasal continuous positive airway pressure. Chest 1995;108:625–30. Malone S, Liu PP, Holloway R, Rutherford R, Xie A, Bradley TD. Obstructive sleep apnea in patients with dilated cardiomyopathy: effects of continuous positive airway pressure. Lancet 1991;338:1480–4. Koehler U, Fus E, Grimm W et al. Heart block in patients with obstructive sleep apnoea: pathogenetic factors and effects of treatment. Eur Respir J 1998;11:434–9. Krieger J, Follenius M, Sforza E, Brandenberger G, Peter JD. Effects of treatment with nasal continuous positive airway pressure on atrial naturetic peptide and arginine vasopressin release during sleep in patients with sleep apnea. Clin Sci (Colch) 1991;80:443–9. Nino-Murcia G, McCann CC, Bliwise DL, Guilleminault C, Dement WC. Compliance and side effects in sleep apnea patients treated with nasal continuous positive airway pressure. West J Med 1989;150:165–9. Hoffstein V, Viner S, Mateika S, Conway J. Treatment of obstructive sleep apnea with nasal continuous positive airway pressure. Patient compliance, perception of benefits, and side effects. Am Rev Respir Dis 1992;145:841–5. Engleman HM, Martin SE, Douglas NJ. Compliance with CPAP therapy in patients with the sleep apnea/hypopnea syndrome. Thorax 1994;49:263–6. McArdle N, Devereux G, Heidarnejad H, Engleman HM, Mackay TW, Douglas NJ. Long term use of CPAP therapy for sleep apnea/hypopnea syndrome. Am J Respir Crit Care Med 1999;159:1108–14. Rolfe I, Olson LG, Sanders NA. Long-term acceptance of continuous positive airway pressure in obstructive sleep apnea. Am Rev Respir Dis 1991;144:1130–3.
118
Medical therapy
120. Weaver TE, Kribbs NB, Pack AI et al. Night to night variability in CPAP use over the first three months of treatment. Sleep 1997;20:278–83. 121. Stauffer JL, Fayter NA, MacLurg BJ. Conjunctivitis from nasal CPAP apparatus. Chest 1998;86:802. 122. Hayes MJ, McGregor FB, Roberts DN, Schroter RC, Pride NB. Continuous nasal positive airway pressure with a mouth leak: effect on nasal mucosal blood flux and nasal geometry. Thorax 1995;50:1179–82. 123. Richards GN, Cistulli PA, Ungar RG, Berthon-Jones M, Sullivan CE. Mouth leak with nasal continuous positive airway pressure increases nasal airway resistance. Am J Respir Crit Care Med 1996;154:182–6. 124. Massie CA, Hart RW, Peralez K, Richards G. Effects of humidification on nasal symptoms and compliance in sleep apnea patients using continuous positive airway pressure. Chest 1999;116:403–8. 125. Mortimore IL, Bradley PA, Murray JA, Douglas NJ. Uvulopharyngopalatoplasty may compromise nasal CPAP therapy in sleep apnea syndrome. Am J Respir Crit Care Med 1996;154:1759–62. 126. Edinger JD, Radtke RA. Use of in vivo desensitization to treat a patient’s
127.
128.
129.
130.
131.
132.
claustrophobic response to nasal CPAP. Sleep 1993;16:678–80. Kribbs NB, Pack AI, Kline LR et al. Objective measurement of patterns of nasal CPAP use by patients with obstructive sleep apnea. Am J Respir Crit Care Med 1993;147:887–95. Reeves-Hoche MK, Meck R, Zwillich CW. Nasal CPAP: an objective evaluation of patient compliance. Am J Respir Crit Care Med 1994;149:149–54. Pépin JL, Krieger J, Rodenstein D et al. Effective compliance during the first 3 months of continuous positive airway pressure. A European prospective study of 121 patients. Am J Respir Crit Care Med 1999;160:1124–9. Hoy CJ, Vennelle M, Kingshott RN, Engleman HM, Douglas NJ. Can intensive support improve continuous positive airway pressure use in patients with the sleep apnea/hypopnea syndrome? Am J Respir Crit Care Med 1999;159:1096–100. Chervin RD, Theut S, Bassetti C, Aldrich MS. Compliance of nasal CPAP can be improved by simple interventions. Sleep 1997;20:284–9. American Sleep Disorders Association. The clinical use of the multiple sleep latency test. Sleep 1992;15:268–76.
6
Therapy with oral appliances
Wolfgang Schmidt-Nowara
Introduction Of the three major therapies for snoring and obstructive sleep apnea (OSA), oral appliances (OAs) are the most recent to have become available. Although OA use is steadily increasing, this mode of therapy is still met with scepticism by some clinicians and resistance by some healthcare payers. In fact, a substantial and growing clinical literature documents the efficacy of this treatment, and it no longer seems reasonable to question whether OAs work. Instead, the only reasonable debate at this time is where to position OA therapy in the spectrum of patient problems and treatment alternatives. This chapter will attempt to do so with a summary of the current understanding of OA therapy for snoring and sleep apnea and with recommendations for their use.
Conceptual development of oral appliance therapy The concept of a dental or oral appliance to facilitate airway patency is not new. At the turn of the century, Pierre Robin proposed this type of treatment in infants with respiratory distress due to micrognathia, a syndrome now known
eponymously by his name.1 Throughout the twentieth century, patent applications can be found for dental devices designed to treat snoring. With the discovery of sleep apnea in the 1960s, with the subsequent appreciation of its substantial prevalence, and with the difficulty of getting patients to accept other therapies, i.e. continuous positive airway pressure (CPAP) and tracheostomy and other operations, the interest in other treatments became acute. Reports of successful therapy of OSA with OAs began to appear in the medical literature in the 1980s.2–4 The 1990s saw a steady succession of clinical reports which clearly documented that OAs can be effective therapy for OSA, that their use is relatively safe, and that, compared to CPAP, patients usually prefer them. Anatomic and functional studies of the upper airway have explored the mechanism of this treatment effect. A review of this clinical literature in 19955 was accompanied by an influential practice parameter developed by the American Academy of Sleep Medicine6 Other updates have appeared since then.7–9 Appliance design and protocols for appliance use have evolved.
Types of oral appliance OA is a generic term for any device inserted in the oral cavity for the purpose of modifying
120
Therapy with oral appliances
A
B
Figure 6.1 (A,B) A mandible-advancing oral appliance, adjustable with a screw mechanism (arrow), custom made from a patient’s dental models in a dental laboratory (Klearway appliance, Great Lakes Orthodontics Ltd, Tonawanda, NY, USA). Note the full dental coverage of both arches. (By courtesy of Dr A. Lowe.)
the airway to relieve snoring and OSA. The types of OA in use today are limited to the mandible-advancing devices and tongue devices. Appliances designed to lift the soft palate, depress the base of the tongue or modify intraoral pressures have fallen by the wayside, due to inefficacy and poor patient tolerance. The mandible-advancing type of OA represents the great majority of OAs in use today, and it is the type of appliance studied in almost all published reports. An example is shown in Figure 6.1. This appliance attaches to both dental arches and repositions the mandible forward of the centric position. Maxillary and mandibular components are connected by an intraoral wire harness that determines the position of the mandibular arch relative to the
maxillary arch. Many similar devices have been developed. A comprehensive listing can be found in a current textbook of sleep medicine.10 The device in Figure 6.1 is adjustable, allowing ‘titration’ of mandibular advance for effect and comfort. All modern OAs of this type have incorporated this feature. The OA illustrated in Figure 6.1 is an example of an adjustable ‘custom’ appliance, meaning that the mandibular advance can be adjusted by means of a screw mechanism and that the appliance is fabricated from dental models in a dental laboratory. Another type of mandible-advancing OA can be made from prefabricated molds containing a thermolabile material (Figure 6.2). These so called ‘boiland-bite’ appliances can be fitted to the patient
Types of oral appliance
Figure 6.2 A mandible-advancing oral appliance, adjustable, prefabricated ‘boil-and-bite’ type, ready for fitting to a patient’s teeth after warming (Therasnore appliance, Distar Inc., Albuquerque, NM, USA).
in the clinic, allowing immediate delivery of the appliance and usually at a lower cost. The illustrated appliance (Figure 6.2) is the adjustable version of a family of ‘boil-andbite’ appliances, with several publications
121
documenting good efficacy and acceptance by patients.11,12 Boil-and-bite appliances tend to be more bulky and less comfortable, are not as easily adjusted, and are less durable over time. Attachment to both arches may be less secure than with custom appliances, resulting in problems with retention during the entire sleep period. In some, the mandibular attachment does not involve the entire arch, accentuating the stress to the lower incisors. The author considers these disadvantages to be substantial and prescribes these appliances only for occasional use, or for a trial of the OA concept before committing to the full cost of a custom appliance, and in other settings when cost is a major constraint. Nevertheless, many patients have used these appliances for long periods of time as the principal treatment for sleep apnea, with good results. Several tongue appliances are available today, but only the tongue-retaining device has been evaluated in published reports by one group of investigators (Figure 6.3),2,5 and their last report appeared in 1991. These papers show a success rate comparable to those of
Figure 6.3 (A,B) The tongue retaining device (Pro-Positioners, Racine, WI, USA). The tip of the tongue is retained in the bulb of the appliance by suction.
A
B
122
Therapy with oral appliances
other OAs. Tongue devices should be considered when an OA is selected but the dentition is inadequate for the stress of a mandibleadvancing OA. Tongue devices are difficult to use, and it takes a dedicated patient to learn to use them consistently all night. This probably accounts for the fact that tongue devices represent only a small fraction of all OAs in use. For this reason, in the rest of this discussion, OA will refer to mandible-advancing appliances unless another type is specifically designated.
Efficacy and use Beginning with case reports, followed by numerous case series, and more recently with several well-controlled clinical trials, a substantial literature documents the efficacy of OAs. Typical published studies report polysomnography before and with use of a mandible-advancing OA in patients with mild to moderate obstructive sleep apnea. This case series study design is more subject to bias than the standard randomized control trial, because of the lack of an untreated control group and the possibility that improvement may be unrelated to treatment. However, in at least one study, when OAs were removed after treatment, OSA was present with severity comparable to baseline, whereas during treatment the apnea–hypopnea index (AHI) was significantly lower than baseline and in OA-removed conditions (Figure 6.4). Furthermore, a randomized controlled trial of OA included a sham treatment arm,13 which should address the methodologic criticisms that have been directed at this literature. Treatment effects in all reports, including the shamcontrolled study, are robust, and the outcomes of all studies are remarkably consistent, indicating that the effects cannot reasonably be attributed to chance.
120 100 80 AHI 60 40 20 0 Pre/out
Post/in
Post/out
Treatment/Orthosis
Figure 6.4 Improvement in AHI with a SnoreGuard oral appliance and return to baseline severity with appliance removal. Note that more severe patients (AHI 40+) are less likely to achieve AHI < 20. (Adapted from Schmidt-Nowara et al.11)
Table 6.1 lists selected studies, including the author’s original report in 1991,11 a state-ofthe-art review in 1995,5 and three more recent studies of adjustable appliances.13–15 In each study, OAs were effective in most, but not all, patients. For example, in the review of 20 papers, comprising studies in 304 patients,5 51% of patients achieved normal levels (AHI < 10) and 70% demonstrated a reduction in pretreatment AHI of 50%, a success criterion frequently used in the surgical literature. The three recent studies13–15 appear to have produced a lower mean AHI and arguably a higher proportion of successfully treated patients, suggesting that titration of an adjustable appliance offers the prospect of more effective treatment. However, in every report some patients are left with an unacceptable level of apnea. Ineffective treatment occurs more frequently in patients with severe OSA (Figure 6.4). Other reasons for treatment
Efficacy and use
123
Table 6.1 Efficacy of oral appliances in obstructive sleep apnea in selected studies. Reference
Patients n
11
20
5
304
13
24
14
75
15
38 20 18
Appliance type
SnoreGuard, non-adjustable MAD, TRD, non-adjustable MAD, sham, adjustable TAP, adjustable Klearway, adjustable AHI 15–30 AHI 30+
AHI without/with OA mean
Treatment response AHI ⭐ 15 (%)
< 50% initial AHI (%)
47/20
40
75
43/19
51*
70
30/14
75
–
44/12
55
81
33/12
71
–
80 61
– –
*
AHI 10) demonstrated reduction in the RDI in 19 of 26 patients (73%) using external dilators.
Treatment Surgical When considering surgical therapy for sleepdisordered breathing in the presence of subjective or objective evidence of nasal obstruction, the following issues are relevant: 1. Is there any indication for nasal surgery alone in the relief of snoring and/or OSA? 2. Should nasal surgery be performed in conjunction with other surgical therapy for snoring and/or OSA? 3. Is there any role for nasal surgery to improve the efficacy and tolerance of CPAP? 4. If nasal surgery is indicated, what procedure(s) should be recommended?
Snoring Nasal surgery has been shown to benefit patients with snoring and even some with sleep apnea.57–61 A study of seven patients with snoring and daytime somnolence, but without OSA, demonstrated objective improvement in daytime somnolence (using sleep latency testing) and decreased snoring. All patients underwent septoplasty and turbinoplasty.1 A recent study of 50 patients with nasal obstruction, snoring and OSA demonstrated subjective improvement in snoring in 34% of patients treated with septoplasty with or without turbinoplasty.62 A study of 29 snoring patients treated with septoplasty and inferior turbinoplasty (and polypectomy when indicated) found a 69% subjective success rate in snoring. However, of the 14 patients with OSA, only 50% had subjective improvement in snoring.63 Fairbanks employs a topical nasal decongestant spray test to preoperatively identify patients who obtain relief from snoring during spray nights. Using this selec-
135
tion criterion, he reports a 75% success rate in treating snoring with nasal surgery alone.58,64 Thus, nasal surgery alone for the treatment of snoring may result in subjective improvement in snoring in about 70% of patients without OSA, and between 33% and 50% of patients with OSA. Test use of a topical nasal decongestant spray may help determine those likely to benefit from nasal surgery alone. However, since no objective data on snoring reduction after nasal surgery are available, suspicion is warranted in interpreting the subjective data. A study comparing subjective and objective snoring improvement after uvulopalatopharyngoplasty (UPPP) found no significant objective improvement despite 80% of patients reporting improved snoring and sleep quality, and 20% of bed partners also reporting no more interference with sleep.65
Obstructive sleep apnea The data regarding the efficacy of nasal surgery alone in the treatment of OSA are even less convincing. A study of 20 patients with OSA reported that 20% of patients were cured with nasal surgery alone (septoplasty, inferior turbinectomy, and/or polypectomy).57 However, a recent study of 50 patients with nasal obstruction and OSA, treated with septoplasty with or without turbinoplasty, found that patients with mild OSA had statistically worsened RDI, while moderate to severe OSA patients had no significant change.62 A study of 40 patients with OSA, included 23 treated with septoplasty, reported a successful reduction in RDI of > 50% in 8 patients (35%).66 Thus it appears that there is no role for routine treatment of OSA with nasal surgery alone, except possibly in cases of massive polyposis.
136
Nasal obstruction and nasal surgery
Combined nasal and pharyngeal surgery Combining nasal surgery with other surgical therapy for snoring and/or OSA is attractive, in that the patient may undergo only one general anesthetic. UPPP, combined with nasal surgery, has shown a 97% subjective rate of snoring improvement in a review of 180 patients.67 However, a study of 347 patients found a 14% complication rate when septoplasty and turbinectomy were performed with UPPP, compared to a 2% complication rate when UPPP was performed alone. These authors recommended staging procedures.68 A study of UPPP alone in the treatment of snoring in 100 patients found similar subjective improvement (96%) except in patients with high nasal resistance by rhinomanometry, where improvement was 78%. They recommended UPPP followed by nasal surgery for those who fail to improve with the UPPP.69 Thus, if nasal surgery is deemed necessary in addition to other surgical therapy for snoring, consideration should be given to staging the procedures, due to a higher complication rate with combined surgery. If concurrent nasal and pharyngeal surgery is performed, the nasal portion should be performed last to prevent bleeding from obscuring visualization. Nasal packing should be avoided, or ventilated nasal stents should be used.70
Nasal surgery to improve CPAP tolerance Nasal surgery has been advocated for patients with nasal obstruction who have difficulty tolerating nasal CPAP. This is a result of the poor compliance with nasal CPAP despite proven benefit in treating sleep-disordered
breathing. However, CPAP compliance is multifactorial, and no single problem accounts for the patient non-compliance.71–76 Yet, unlike UPPP, which can increase problems with mouth leakage during nasal CPAP use, nasal surgery generally reduces nasal resistance and is not associated with worsening of CPAP compliance.77 A study of 50 patients with nasal obstruction and OSA demonstrated a statistically significant reduction in CPAP pressure levels after nasal surgery (septoplasty with or without inferior turbinoplasty).62 A recent placebo-controlled study specifically addressed the role of improving CPAP tolerance using radiofrequency treatment to perform inferior turbinoplasty. CPAP tolerance subjectively improved by 29% in patients treated with radiofrequency compared to a 10% worsening in patients treated with placebo. Objective outcome measures were not statistically significant.78
Procedures The decision regarding what type of nasal surgery to recommend in cases of nasal obstruction associated with sleep-disordered breathing is complex. Certainly, in patients who have symptomatic nasal obstruction refractory to medical management and have sleep-disordered breathing, nasal surgery is indicated for the management of the obstruction and may secondarily improve the sleep disorder. Selection of the appropriate surgical procedure is based upon accurate diagnosis of the level(s) and cause(s) of obstruction. Septoplasty (Figures 7.6–7.9) may be the most common procedure used to treat nasal obstruction associated with sleep-disordered breathing. It is recommended in cases of severe deviation with symptomatic obstruction refractory to medical therapy. Despite
Treatment
137
Area of mucosal elevation Remove or score cartilage
Secure with 3-0 vicryl
165-3 165-6
Elevator
Swing back into midline
Figure 7.6 A small incision is made inside the nose, which allows the surgeon to elevate the mucosa from the periosteum, and perichondrium from the bone and cartilage of the nose.
Figure 7.7 Bowing of the nasal septum can sometimes be corrected by resecting part of the bowed septum.
Resected area of cartilage
165-7 165-9
Cartilage scored on concave side
Scored cartilage
Overriding cartilage to be resected
Sutures Maxillary spine
Excess overriding cartilage excised
Figure 7.8 When the anterior cartilage is badly deviated, it can sometimes be scored on the concave side. This allows the cartilage to resume a more normal flat shape. Both excessive overriding cartilages must be excised.
Figure 7.9 When overriding cartilage is part of the obstruction problem, this can be excised.
138
Nasal obstruction and nasal surgery
objective evidence of reduced nasal resistance after septoplasty, 22% of patients continue to report symptoms of nasal obstruction.79,80 Efficacy of septoplasty in the management of snoring and OSA is discussed above. Inferior turbinate surgery may be performed alone, or in conjunction with other nasal surgery. Recently, turbinectomy has fallen out of favor, and various techniques for turbinoplasty have been described, including: outfracturing; submucosal resection; and submucosal ablation with electrocautery or radiofrequency energy.81 Attention is generally focused anteriorly, in the region of the nasal valve. A randomized study of 50 patients undergoing septoplasty or septoplasty with contralateral inferior turbinoplasty for nasal obstruction, found no subjective or objective evidence of improvement with the addition of turbinoplasty.80 Thus, the role of turbinoplasty remains controversial. Use of the Cottle maneuver, in conjunction with a trial of external nasal dilators, may aid in identifying patients with nasal valve collapse.54 Surgery to prevent nasal valve collapse has been reported for the treatment of OSA in two patients;82 however, conclusive data are lacking. Use of cartilage spreader grafts between the upper lateral cartilage and septum is standard therapy for this problem.83 A recent report of nasal alar rim reconstruction using cartilaginous struts placed along the caudal alar rim suggests equal or improved efficacy with less technical difficulty.84 Middle meatal surgery is indicated for nasal obstruction in cases of chronic sinusitis and sinonasal polyposis refractory to medical therapy. Rarely, resection of a concha bullosa or enlarged middle turbinate may be indicated to relieve symptoms of nasal obstruction associated with sleep-disordered breathing.22 Adenoidectomy is indicated in the management of nasal obstruction and snoring or OSA
secondary to adenoid hypertrophy. This, coupled with tonsillectomy, is often curative in the pediatric population. The goal of surgery is patent posterior nasal choanae.22 UPPP has been shown to reduce nasal airway resistance by eliminating obstruction in the region of the nasopharynx and possibly reducing anterior nasal mucosal imflammation.85
Conclusion Evaluation of symptoms and signs of nasal airway obstruction is an essential component in the assessment of the patient with snoring and/or OSA. While nasal obstruction may cause snoring and be a cofactor in the development of OSA, it is rarely the sole cause. Treatment of nasal obstruction associated with sleep-disordered breathing should initially be medical and behavioral. Snoring patients with nasal obstruction refractory to medical and behavioral therapy may be candidates for mechanical devices (external nasal dilators, nasal CPAP, or intraoral appliances) or nasal surgery. Test use of a topical nasal decongestant spray and/or an external nasal dilator may help to identify those likely to achieve subjective benefit from nasal surgery alone. Combining nasal and palatal surgery markedly increases the complication rate, and consideration should be given to staging procedures. Patients with nasal obstruction and OSA are best treated with nasal CPAP, except possibly in: young patients with significant adenoid obstruction; massive nasal polyposis; or neoplastic disease. In patients unable to tolerate nasal CPAP due to nasal symptoms related to nasal obstruction, nasal surgery may reduce CPAP pressure levels and subjectively improve CPAP tolerance. When
Conclusion
139
Nasal obstruction and sleep-disordered breathing
Polysomnography
Snoring
OSA
Medical therapy therapy Medical Behavioral therapy therapy Behaviour
CPAP
Tolerate CPAP?
Improved?
Yes
No
Yes
No
Continue therapy
Topical decongestant test External dilator test
Continue CPAP
Nasal symptoms or high CPAP pressures?
Symptoms improved?
Yes
No
Nasal surgery or external nasal dilator
CPAP, IOA or UPPP
Yes
No
Nasal surgery and/or medical therapy to increase CPAP tolerance
OSA OSA surgery, surgery, IOA, and/or and/or IOA, behavioral behavioural therapy therapy
Figure 7.10 A suggested protocol for the management of nasal obstruction and sleep-disordered breathing. Exceptions may include patients with adenoid hypertrophy, massive polyps, neoplasm, or severe structural deformity causing obstructive symptoms during daytime. OSA, obstructive sleep apnea; CPAP, continuous positive airway pressure; UPPP, uvulopalatopharyngoplasty; IOA, intraoral appliance.
140
Nasal obstruction and nasal surgery
nasal surgery is planned, it should be directed towards the area and underlying etiology causing the obstruction. A protocol is suggested for the patient with nasal obstruction and sleep-disordered breathing (Figure 7.10).
11.
12.
References 13. 1. Papsidero MJ. The Nose and its Impact on Snoring and Obstructive Sleep Apnea. New York: Raven Press, 1994. 2. Carpenter JG. Mental aberration and attending hypertrophic rhinitis with subacute otitis media. JAMA 1892;19:539–42. 3. Cole P, Haight JSJ. Posture and the nasal cycle. Ann Otol Rhinol Laryngol 1986;95:233–7. 4. Kerr P, Miller T, Buckle P et al. The importance of nasal resistance in obstructive sleep apnea syndrome. J Otolaryngol 1992;21:189–95. 5. Woodson BT, Garancis JC, Toohill RJ. Histopathologic changes in snoring and obstructive sleep apnea syndrome. Laryngoscope 1991;101:1318–22. 6. Morrison DL. Nasal resistance and sleep apnea. Am Rev Resp Dis 1993;148:606–11. 7. Olsen KD, Kern EB, Westbrook PR. Sleep and breathing disturbance secondary to nasal obstruction. Otolaryngol Head Neck Surg 1981;89:804–10. 8. Zwillich CW, Zimmerman J, Weil JV. Effects of nasal obstruction on sleep in normal man (abstract). Clin Res 1979;27:405A (abstract). 9. Morris HD, Doyle PJ, Riding KH et al. The effects of posterior packing on pulmonary function in posterior epistaxis. Trans Am Acad Ophthalmol Otolaryngol 1976;82:504–8. 10. Lavie P, Fischel N, Zomer J et al. The effects of partial and complete mechanical occlusion of the nasal passages on sleep structure and
14.
15.
16.
17.
18.
19.
20.
21.
22.
breathing in sleep. Acta Otolaryngol (Stockh) 1983;95:161–6. Maurice JC, Marc I, Carrier G et al. Effects of mouth opening on upper airway collapsibility in normal sleeping subjects. Am J Respir Crit Care Med 1996;153:255–9. Young T, Finn L, Kim H. Nasal obstruction as a risk factor for sleep-disordered breathing. The University of Wisconsin Sleep and Respiratory Research Group. J Allergy Clin Immunol 1997;99:S757–62. McNicholas WT, Tarlo S, Cole P et al. Obstructive apneas during sleep in patients with seasonal allergic rhinitis. Am Rev Respir Dis 1982;126:625–8. Lugaresi E, Mondini S, Zucconi M et al. Staging of heavy snorers’ disease. A proposal. Bull Euro Physiopathol Respir 1983;19:590–4. Friberg D, Gazelius B, Hokfelt T et al. Abnormal afferent nerve endings in the soft palatal mucosa of sleep apneics and habitual snorers. Regul Pept 1997;71:29–36. Sekosan M, Zakkar M, Wenig BL et al. Inflammation in the uvula mucosa of patients with obstructive sleep apnea. Laryngoscope 1996;106:1018–20. Peter JH, Kohler V, Mayer J et al. The prevalence of sleep apnea activity. Sleep Res 1985;14:197. Petruson B, Bjuro T. The importance of nosebreathing for the systolic blood pressure rise during exercise. Acta Otolaryngol (Stockh) 1990;109:461–6. White DP, Cadieux RJ, Lombard RM et al. The effects of nasal anesthesia on breathing during sleep. Am Rev Resp Dis 1985;132:972–5. Miljeteig H, Savard P, Mateika S et al. Snoring and nasal resistance during sleep. Laryngoscope 1993;103:918–23. Miyazaki S, Itasaka Y, Ishikawa K, Togawa K. Influence of nasal obstruction on obstructive sleep apnea. Acta Otolaryngol 1998;537:43–6. Mirza N, Lanza, D. The nasal airway and
References
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
obstructed breathing during sleep. Otolaryngol Clin North Am 1999;32(2):243–62. Bruintjes TD, van Olphen AF, Hillen B et al. A functional anatomic study of the relationship of the nasal cartilages and muscles to the nasal valve area. Laryngoscope 1998;108:1025–32. Proctor DF. The upper airways. Nasal physiology and defense of the lungs. Am Rev Respir Dis 1997;115:97–129. Gray LP. Deviated nasal septum. Ann Otol Rhinol Laryngol 1978;87(suppl 50, pt 3): 3–20. Shellock FG, Schatz CJ, Julien P et al. Occlusion and narrowing of the pharyngeal airway in obstructive sleep apnea: evaluation by ultrafast spoiled GRASS MR imaging. Am J Radiol 1992;158:1019–24. Morrison DL, Launois SH, Isono S et al. Pharyngeal narrowing and closing pressures in patients with obstructive sleep apnea. Am Rev Respir Dis 1993;148:606–11. Craig TJ, Teets S, Lehman EB, Chinchilli VM, Zwillich C. Nasal congestion secondary to allergy rhinitis as a cause of sleep disturbance and daytime fatigue and the response to topical nasal corticosteriods. J Allergy Clin Immunol 1998;101(5):633–7. Scharf MB, Cohen AP. Diagnostic and treatment implications of nasal obstruction in snoring and obstructive sleep apnea. Ann Allergy Asthma Immunol 1998;81:279–90. Smith PL, Gold AR, Meyers DA et al. Weight loss in mildly to moderately obese patients with obstructive sleep apnea. Ann Intern Med 1985;103:850–5. Strobel RJ, Rosen RC. Obesity and weight loss in obstructive sleep apnea: a critical review. Sleep 1996;19:104–15. Bonora M, Shields GI, Knuth SL et al. Selective depression by ethanol of upper airway respiratory motor activity in cats. Am Rev Respir Dis 1984;130:156–61. Bonora M, St John WM, Bledsoe TA. Differential elevation by protriptyline and
34.
35.
36. 37.
38.
39.
40.
41.
42.
43.
44.
45.
141
depression by diazepam for upper airway respiratory motor activity. Am Rev Respir Dis 1985;131:41–5. Issa FG, Sullivan CE. Alcohol, snoring and sleep apnea. J Neurol Neurosurg Psychiatry 1982;45:353–9. Robinson RW, White DP, Zwillich CW. Moderate alcohol ingestion increases upper airway resistance in normal subjects. Am Rev Respir Dis 1985;132(6):1238–41. Cartwright R. Effect of sleep position on sleep apnea severity. Sleep 1984;7:110–14. Cartwright R, Lloyd S, Lilie J et al. Sleep position training as treatment for sleep apnea syndrome: a preliminary study. Sleep 1985;8:87–94. Cartwright R, Ristanovic R, Diaz F et al. A comparative study of treatments for positional sleep apnea. Sleep 1991;14:546–52. George CF, Miller TW, Kryger MH. Sleep apnea and body position during sleep. Sleep 1988;11:90–9. Findley L, Unverzadt M, Suratt P et al. Automobile accidents in patients with obstructive sleep apnea. Am Rev Respir Dis 1988;138:337–40. George C, Nickerson P, Hanly P et al. Sleep apnea patients have more automobile accidents. Lancet 1987;2:447. Stoohs R, Guilleminault C, Itoi A et al. Traffic accidents in commercial long-haul truck drivers: the influence of sleepdisordered breathing and obesity. Sleep 1994;17:619–23. Strohl K, Bonnie R, Findley L et al. Sleep apnea, sleepiness and driving risk. Am J Respir Crit Care Med 1994;150:1463–73. Sullivan CE, Grunstein, RR. Continuous positive airway pressure in sleep-disordered breathing. In: Kryger M, Roth T, Dement W, eds. Principles and Practice of Sleep Medicine, 2nd edn. Philadelphia: WB Saunders, 1994: 694–705. Sullivan CE, Issa FG, Berthon-Jones M et al. Reversal of obstructive sleep apnea by
142
46.
47.
48.
49.
50.
51.
52.
53.
54.
55.
Nasal obstruction and nasal surgery
continuous positive airway pressure applied though the nares. Lancet 1981;1:862–5. Wilcox I, Grunstein RR, Hender JA et al. Effect of nasal continuous positive airway pressure during sleep on 24–hour blood pressure in obstructive sleep apnea. Sleep 1993;16:539–44. Schechter GL, Ware JC, Perlstrom J, McBrayer RH. Nasal patency and the effectiveness of nasal continuous positive air pressure in obstructive sleep apnea. Otolaryngol Head Neck Surg 1998;118(5):643–7. Schmidt-Nowara W, Lowe A, Wiegand L et al. An American Sleep Disorders Association review: oral appliances for the treatment of snoring and obstructive sleep apnea: a review. Sleep 1995;18:501–10. Wali SO, Kryger MH. Medical treatment of sleep apnea. Curr Opin Pulm Med 1995;1:498–503. American Sleep Disorders Association Standards of Practice Committee. Practice parameters for the treatment of snoring and obstructive sleep apnea with oral appliances. Sleep 1995;18:511–13. Wilhelmsson B, Tegelberg A, WalkerEngstrom ML et al. A prospective randomized study of a dental appliance compared with uvulopalatopharyngoplasty in the treatment of obstructive sleep apnea. Acta Otolaryngol 1999;119(4):503–9. Todorova A, Schellenberg R, Hofmann HC, Dimpfel W. Effect of the external nasal dilator Breathe Right on snoring. Eur J Med Res 1998;3(8):367–79. Scharf MB, Brannen DE, McDannold M. A subjective evaluation of a nasal dilator on sleep and snoring. Ear Nose Throat J 1994;73:395–401. Gosepath J, Amedee RG, Romantschuck S, Mann WJ. Breathe Right nasal strips and the respiratory disturbance index in sleep related breathing disorders. Am J Rhinol 1999;13(5):385–9. Hoijer U, Ejnell H, Hedner J, Petruson B, Eng
56.
57.
58. 59.
60.
61.
62.
63. 64.
65.
66.
LB. The effects of nasal dilation on snoring and obstructive sleep apnea. Arch Otolaryngol Head Neck Surg 1992;118(3):281–4. Hoffstein V, Mateika S, Metes A. Effect of nasal dilation on snoring and apneas during different stages of sleep. Sleep 1993;16:360–5. Series F, St Pierre S, Carrier G. Effects of surgical correction of nasal obstruction in the treatment of obstructive sleep apnea. Am Rev Respir Dis 1992;146:1261–5. Fairbanks DN. Effect of nasal surgery on snoring. South Med J 1985;78:268–70. Hester TO, Phillips B, Archer SM. Surgery for obstructive sleep apnea: effects on sleep, breathing and oxygenation. South Med J 1985;78:268–70. Fairbanks DNF. Snoring: surgical vs nonsurgical management. Laryngoscope 1984;94:1188–92. Silvoniemi P, Suonpaa J, Sipila J, Grenman R, Erkinjuntti M. Sleep disorders in patients with severe nasal obstruction due to septal deviation. Acta Otolaryngol 1997;529:199–201. Friedman M, Tanyeri H, Lim JW, Landsberg R, Vaidyanathan K, Caldarelli D. Effect of improved nasal breathing on obstructive sleep apnea. Otolaryngol Head Neck Surg 2000;122:71–4. Woodhead CJ, Allen MB. Nasal surgery for snoring. Clin Otolaryngol 1994;19:41–4. Fairbanks DN. Predicting the effect of nasal surgery on snoring: a simple test. Ear Nose Throat J 1991;70:50–2. Miljeteig H, Mateika S, Haight JS, Cole P, Hoffstein V. Subjective and objective assessment of uvulopalatopharyngoplasty for treatment of snoring and obstructive sleep apnea. Am J Respir Crit Care Med 1994;150(5 pt 1):1286–90. Caldarelli DD, Cartwright RD, Lilie JK. Obstructive sleep apnea: variations in surgical management. Laryngoscope 1985;95(9 pt 1):1070–3.
References 67. Piche J, Gagnon NB. Snoring, apnea, and nasal resistance. J Otolaryngol 1996;25(3):150–4. 68. Mickelson SA, Hakim I. Is postoperative intensive care monitoring necessary after uvulopalatopharyngoplasty? Otolaryngol Head Neck Surg 1998;119(4):352–6. 69. Virkkula P, Lehtonen H, Malmberg H. The effect of nasal obstruction on outcomes of uvulopalatopharyngoplasty. Acta Otolaryngol Suppl 1997;529:195–8. 70. Olsen KD. The role of nasal surgery in the treatment of obstructive sleep apnea. Op Tech Otolaryngol Head Neck Surg 1991;2:63–8. 71. Reeves-Hoche MK, Hudgel DW, Meck R et al. Continuous versus bilevel positive airway pressure for obstructive sleep apnea. Am J Respir Crit Care Med 1995;151:443–9. 72. Kribbs NB, Pack AI, Kline LR et al. Objective measurement of patterns of nasal CPAP use by patients with obstructive sleep apnea. Am Rev Respir Dis 1993;147:887–95. 73. Reeves-Hoche MK, Meck R, Zwillich CW. Nasal CPAP: an objective evaluation of patient compliance. Am J Respir Crit Care Med 1994;149:149. 74. Engleman HM, Martin SE, Douglas NJ. Compliance with CPAP therapy in patients with sleep apnoea/hypopnoea syndrome. Thorax 1994;49:263. 75. Rauscher H, Formanek D, Popp W, Zwick H. Self reported vs. measured compliance with nasal CPAP for obstructive sleep apnea. Chest 1993;103:1675. 76. Meurice JC, Dore P, Paquereau J et al. Predictive factors of long-term compliance with nasal continuous positive airway pressure treatment in sleep apnea syndrome. Chest 1994;105:429.
143
77. Mortimore IL, Bradley PA, Murray JA, Douglas NJ. Uvulopalatopharyngoplasty may compromise nasal CPAP therapy in sleep apnea syndrome. Am J Respir Crit Care Med 1996;154(6 pt 1):1759–62. 78. Powell NB, Riley RW, Zonato AI, Li KK, Troell RJ. Radiofrequency treatment of turbinate hypertrophy to improve nasal CPAP usage. Otolaryngol-Head & Neck Surg 1999;121:P54. 79. Gordon ASD, McCaffrey TV, Kern EB et al. Rhinomanometry for preoperative and postoperative assessment of nasal obstruction. Otolaryngol Head Neck Surg 1989;101:20–6. 80. Illum P. Septoplasty and compensatory inferior turbinate hypertrophy: long-term results after randomized turbinoplasty. Eur Arch Otorhinolaryngol Suppl 1997;1:S89–92. 81. Li KK, Powell NB, Riley RW, Troell RJ, Guilleminault C. Radiofrequency volumetric tissue reduction for treatment of turbinate hypertrophy: a pilot study. Otolaryngol Head Neck Surg 1998;119(6):569–73. 82. Irvine BW, Dayal VS, Phillipson EA. Sleep apnea due to nasal valve obstruction. J Otolaryngol 1984;13:37–8. 83. Toriumi DM. Open rhinoplasty. Facial Plastics Clin North Am 1993;1:102–8. 84. Troell RJ, Powell NB, Riley RW, Li KK. Evaluation of a new procedure for nasal alar rim and valve collapse: nasal alar rim reconstruction. Otolaryngol Head Neck Surg 2000;122(2):204–11. 85. Kawano K, Usui N, Kanazawa H, Hara I. Changes in nasal and oral respiratory resistance before and after uvulopalatopharyngoplasty. Acta Otolaryngol Suppl 1996;523:236–8.
8
Tracheotomy
Jonas Johnson and Jack Gluckman
Introduction Patients with obstructive sleep apnea (OSA) have a normally patent airway when awake. During sleep there is obstruction at a site or sites in the upper airway which results in hypoxemia and multiple arousals. Theoretically, tracheotomy is the ideal treatment for OSA, particularly if the tracheotomy tube can be covered or plugged during the day and opened during sleep. As the ‘perfect’ solution for OSA it is essential that the diagnosis of OSA be made prior to intervening with tracheotomy. Tracheotomy is imperfect as treatment for most patients with OSA. This is reflective of the fact that patients and their families perceive a tracheotomy to be unsightly and intrusive. It is difficult to camouflage and serves to ‘label’ the patient. Nevertheless, tracheotomy is highly effective in the management of OSA, resulting in immediate relief of symptoms, and should be considered in patients with severe life-threatening disease and when other approaches have failed. Patients with other sleep-related disorders are unlikely to benefit from tracheotomy. Similarly, patients with so-called central sleep apnea in whom there is inadequate respiratory drive would be unlikely to benefit from a tracheotomy. Prior to planning surgical
intervention, consultation with the sleep laboratory and careful evaluation of the polysomnogram is an essential component of treatment planning.
Historical review Guilleminault et al reported the results of 50 patients with OSA treated with tracheotomy.1 Apnea indices were uniformly greater than 65 events per hour. All patients reported dramatic reduction in apnea-associated symptomatology. Subsequent study in the sleep laboratory with the tracheotomy open and patent showed that apnea indices had been reduced to fewer than five per hour per individual. Occlusion of the tracheotomy tube resulted in recurrence of OSA. Other authors have noted similar, almost uniformly successful outcomes following tracheotomy for OSA.2,3 Patients experienced improved alertness with less daytime somnolence. Some patients have experienced reduction of hypertension and associated weight loss. Motta et al studied six patients with hemodynamic monitoring before and after tracheotomy.2 The variables evaluated included heart rate, pulmonary artery
146
Tracheotomy
pressure, femoral artery pressure and arterial oxygen tension. Following tracheotomy, significant reductions were noted in pulmonary artery pressure and mean femoral artery pressure. There was also an increase in arterial oxygen tension.
Indications Tracheotomy is indicated in patients with severe OSA who have been unresponsive to or non-compliant with other therapeutic interventions. There does not exist a standard apnea index or respiratory disturbance index for which tracheotomy is uniformly indicated. Patients with severe symptomatology, such as pathologic and dangerous hypersomnolence, may be thankful for the immediate relief offered by tracheotomy. Patients with cor pulmonale, apnea-associated cardiac arrhythmia and severe oxygen desaturation may realize significant benefit subsequent to tracheotomy. Additionally, some surgeons feel that perioperative tracheotomy reduces the potential for postoperative morbidity and mortality in patients with severe sleep apnea who require pharyngeal surgery. In general, patients with OSA with documented apnea indexes in excess of 50 events per hour should be offered a tracheotomy if they cannot comply with the regular use of continuous positive airway pressure (CPAP). Severely affected patients may be managed perioperatively more safely with tracheotomy if they elect to undergo surgery directed at the upper airway. Patients with documented severe apnea, who have previously undergone airway surgery and failed to respond, are also candidates with whom tracheotomy should be discussed.
Technique General factors Surgeons and anesthesiologists alike are cautioned to avoid sedation in patients with severe OSA. Preoperative evaluation of mandibular excursion and the condition of the dentition as well as flexible transnasal evaluation of the airway allow the surgeon and anesthesiologist alike to prepare for administration of anesthesia and subsequent general endotracheal intubation. Simple abundance of soft tissue (tongue) should not impede intubation in experienced hands. Other factors which may make intubation even more difficult, such as retrognathia or temporomandibular joint ankylosis, call for flexible fiberoptic transnasal intubation or tracheotomy performed under local anesthesia. Tracheotomy is a surgical procedure widely performed by surgeons trained in a variety of disciplines. It is generally acknowledged to be quick and simple in appropriately trained hands. Tracheotomy in the ‘average’ patient with severe OSA may challenge these generally held concepts. Some patients present with morbid obesity resulting in excessive soft tissue overlying the trachea and often multiple folds of soft tissue (double and triple chins) which may serve to occlude the tracheotomy tube. Standard tracheotomy tubes may not fit. The potential for granuloma formation, soft tissue excoriation and an imperfect hygienic situation is high. In view of the fact that tracheotomy performed for OSA is intended for long-term use, a ‘permanent’ skin-lined stoma is preferable to the technique utilizing an endotracheal tube that most surgeons are conversant with (Figure 8.1A,B,C,D). The additional difficulty and time required to
Technique develop a skin-lined stoma in a morbidly obese patient suggest that general anesthesia with intubation and airway protection is the preferred approach. The technique used in performing the tracheotomy in the patients with OSA must be reflective of the intended duration of use of the tracheotomy and the patient’s particular morphology. In some instances, a tracheotomy is intended to be temporary to accompany other procedures in high-risk patients. Under these circumstances, it may be the intention of the surgeon to remove the tracheotomy when the patient has recovered from the other procedures and has shown documented relief of OSA. A standard tracheotomy may be undertaken under these circumstances; however, a special long-length tube may be required in some patients. A permanent skinlined tracheostomy is preferred if the intention is to support the patient with a tracheotomy long term. A variety of techniques to form a permanent skin-lined track have been described.4–6 In each case, a skin paddle is outlined and mobilized. The skin paddle invariably requires defatting such that it can be advanced and sutured directly to the tracheal margin. Preoperative estimation of the depth of soft tissue may help in acquisition of a properly sized tracheotomy tube. The availability of a tube with an inner cannula is invaluable in nursing care and preparing for discharge training. During performance of the procedure, meticulous attention to hemostasis with ligature or oversewing of bleeders is encouraged. The thyroid should be divided at the isthmus, oversewn and mobilized laterally to prevent it from compromising the stoma. Similarly, it may be necessary to displace the strap muscles laterally with a suture to the tendon of the sternomastoid muscle. A superiorly based tracheal flap using the third and
147
fourth anterior rings is sutured to the upper skin flap. Eliachar has described a self-sustaining, tube-free tracheotomy which would suit most patients with OSA. A tube-free tracheotomy would minimize some of the unwanted complaints that patients have regarding conventional tracheotomy. This would be ideal if patients could generate speech and cough without the need to occlude the stoma or to use stents or valves. The Eliachar technique is performed through an omegashaped incision situated over the intended tracheotomy site (Figure 8.1E). Subsequently, skin flaps are elevated and adipose tissue is excised. This technique requires extensive undermining to allow tension-free mobilization of the flaps. The thyroid isthmus is transected and oversewn. The thyroid lobes are sutured laterally underneath the muscle (Figure 8.1F). When excessive submental fat is present, it must be excised, sometimes including an oval strip of skin (Figure 8.1G). The skin flaps are then advanced to provide a tension-free approximation to the margins of the tracheal fenestra (Figure 8.1H). An essential component comprises two suspensory sutures designed to sustain the elevation of the lower skin flap. These sutures (2–0 silk) are passed through the subcutaneous tissue of the undersurface of the flap and subsequently through the tendons overlying the sternoclavicular joint. A supplementary sling procedure is designed to allow tube-free tracheotomy function for effective cough and speech. This procedure is advocated as a staged adjuvant technique for patients who are unable to adequately constrict and seal the primary stoma. Interested readers are encouraged to consult the primary report.4 Postoperatively, patients are maintained in the hospital for monitoring and home care teaching prior to discharge. Some patients
148
Tracheotomy
} 1.5 cm
}
3–6 cm
A B C
D
E
Figure 8.1 (A) An inferiorly based flap is elevated. Subcutaneous fat is excised. The flap is sutured directly to the trachea, skin to mucosa. (B) Schematic lateral view of the stoma. (C) An alternative design is the use of two laterally based flaps. Again, the fat is excised and the skin is sutured directly to the mucosa. (D) In the obese neck, this design improves the vascularity and the length of the flap. (E) With the patient supine and the neck in moderate extension, an incision is designed one finger’s breadth above the clavicles, with its vertex overlapping the cricoid arch.
Technique
149
Suspended skin Excised panus
F
G
H
I
Figure 8.1 continued (F) The thyroid lobes and the strap muscles are everted sideways away from the trachea and sutured to the undersurface of the sternal tendon of the sternocleidomastoid muscle. The superiorly based anterior tracheal wall flap is elevated. (G) Excess fat, which may occlude the stoma, must be excised. When indicated, an oval strip of skin is suspended away from the stoma and sutured to the hyoid bone. Two continuous-suction drain tubes are inserted through the lower skin flap. (H) The lower skin flap is extensively undermined and advanced in a cephalad direction to provide tension-free approximation to the planned lower margins of the tracheal fenestra. (I) Side-view of the stage reached in (H).
150
Tracheotomy
have such excessive submental soft tissue that this needs to be taped or otherwise supported to avoid direct obstruction of the tracheotomy tube. Local hygiene requires application of antibiotic ointment and occasional resection of granulation tissue. Sudden relief of chronic upper airway obstruction may lead to postobstructive pulmonary edema and adult respiratory distress syndrome. Chronic subtotal respiratory obstruction is transmitted to the pulmonary alveoli as increased alveolar pressure. When this is relieved by tracheotomy, there may be an outpouring of interstitial fluid into the alveoli (congestive heart failure). Patients with right heart failure and severe cardiopulmonary compromise should be identified prospectively and placed on a respirator in the immediate postoperative period, employing positive end expiratory pressure (PEEP). The patients can be then weaned over the ensuing 18–36 h.
Tracheotomy tube considerations The choice of a tracheotomy tube for longterm use in the patient with OSA must first reflect the patient’s specific needs. The ideal tracheotomy tube can be opened at night to allow breathing during sleep and occluded all day, such that the patient will be able to talk around it and can pursue a nearly normal active life. The ideal tube is comfortable, atraumatic and has a low profile, allowing it to be easily covered with clothing. The tracheotomy plug should be easy to use and securely attachable. A removable intercannula for cleaning is ideal. Patients exhibiting massive obesity create special challenges to
achieve a ‘fit.’ Additionally, local hygiene is a serious challenge in the early convalescent period, until such time as there is complete healing between the skin of the neck and the mucosa of the trachea, thereby forming a mature tract. Until this is achieved, chronic drainage and foreign body granuloma formation is the rule rather than the exception. The circumferential stoma tends to contract and stenose. All of these issues serve to challenge the care-giver to provide a reliable system which can be cared for at home by the average patient. New tubes with inner cannulae are available. Extra-long tracheotomy tubes which are shapeable are currently available, but do not allow routine use of an inner cannula. Many of the standard tracheotomy tubes have excessive anterior projections and some do not allow reliable attachment of a tracheotomy plug. Stoma buttons, while theoretically ideal, are sometimes poorly retained and extruded. The Montgomery cannula works well in many patients. The reader needs to communicate directly with the manufacturers in selecting the best-suited device for each individual patient. Eliachar et al describe a system of biocompatible medical grade silicone stents which are smooth, flexible, and non-irritating to skin and mucosa.7 The stent shaft serves to connect skin to mucosa and obviates the need for an inner cannula. Internal and external flanges resist expulsion during speech and cough. These tubes are adapted with a fitted plug. The stent is unplugged during sleep. These tubes, available through Hood Laboratories (Pembroke, MA, USA) come in a variety of sizes and profiles. Montgomery has introduced a tube system which also works as a grommet with no tube actually in the airway. A series of washers allows custom fitting to a variety of neck sizes.
References
151
Troubleshooting
Conclusion
Tube displacement is a potential complication in the early postoperative period. Inasmuch as these patients do not have total respiratory obstruction while awake, replacement of the tube is not an emergency and should be undertaken by experienced staff with adequate instrumentation and lighting to ensure that the tube is properly replaced. Creation of a false passage and pneumothorax are unnecessary sequelae of hasty maneuvers. Crusts, granulation tissue and other wound care problems respond to local hygiene, frequent tube cleaning and changes, and occasional laser vaporization of granulation. Fletcher describes recurrence of sleep apnea in a patient with OSA treated with tracheotomy.8 This patient experienced initial relief of OSA following tracheotomy. Four years later and after an approximate 50 lb weight gain, the patient developed recurrence of nocturnal apnea. Further evaluation demonstrated that the patient had central apnea which required home nocturnal positive-pressure ventilation via cuff tracheostomy tube. Some investigators have proposed a common factor leading to either obstructive or central nocturnal apnea. Central apneas may result from the interaction between hypercarbia and hypoxemia. If hypoxemia results in hyperpnea causing the arterial CO2 level to go below the apneic CO2 threshold, the result may be central apnea. Fletcher suggested that cases such as this may lend support to a common mechanism for all sleep apnea. The ultimate goal may be to find treatment for both types of apnea which improves the problem at the controller level rather than the site of obstruction. Currently, the site of obstruction is treated by CPAP and surgery.
He et al report that mortality of OSA is reduced following tracheotomy. Tracheotomy is as effective as nasal CPAP in reduction of cardiopulmonary morbidity attributed to OSA.9 Tracheotomy is perceived to be an intrusive, mutilating intervention. Most patients and families are motivated to explore alternative therapies. When symptoms are severe and other treatments have failed or are unacceptable tracheotomy may be a great help in the care of some of the most difficult patients with OSA. The duration of commitment to tracheotomy may reasonably be based upon the response to other therapies such as weight reduction, tongue surgery, or maxillomandibular advancement. Patient acceptance may sometimes be enhanced under these circumstances.
References 1.
2.
3.
4.
5.
Guilleminault C, Simmons B, Motta J et al. Obstructive sleep apnea syndrome and tracheostomy. Long-term follow-up experience. Arch Intern Med 1981;141:985–8. Motta J, Guilleminault C, Schroeder JS, Dement WC. Tracheostomy and hemodynamic changes in sleep-induced apnea. Ann Intern Med 1978;89: 454–8. Simmons FB. Tracheostomy in the sleep apnea syndrome. Ear Nose Throat J 1984;63:222–6. Eliachar I, Zohar S, Golz A, Joachims H, Goldsher M. Permanent tracheostomy. Head Neck Surg 1984;7:99–103. Sahni R, Blakley B, Maisel RH. ‘How I do it’ —head and neck and plastic surgery. A
152
6.
7.
Tracheotomy
targeted problem and its solution. Flap tracheostomy in sleep apnea patients. Laryngoscope 1985;95:221–3. Mickelson SA. Upper airway bypass surgery for obstructive sleep apnea syndrome. Otolaryngol Clin North Am 1998;31(6):1013–23. Eliachar I. Unaided speech in long-term tubefree tracheostomy. Laryngoscope 2000;110:749–60.
8.
9.
Fletcher EC. Recurrence of sleep apnea syndrome following tracheostomy. A shift from obstructive to central apnea. Chest 1989;96:205–9. He J, Kryger MH, Zorick FJ, Conway W, Roth T. Mortality and apnea index in obstructive sleep apnea. Experience in 385 male patients. Chest 1988;94:9–14.
9
Uvulopalatopharyngoplasty
Aaron E Sher
Uvulopalatopharyngoplasty (UPPP), introduced by Fujita in 1981, was the first surgical procedure specifically developed to treat patients with obstructive sleep apnea syndrome (OSAS).1 Classical otorhinolaryngologic techniques (nasal septal reconstruction, turbinate mucosal cauterization, turbinate outfracture, and tonsillectomy) previously applied to eliminate sleep-related upper airway collapse produced variable and often inadequate results.2 Only tracheotomy was uniformly successful in eliminating OSAS. Fujita, seeking an effective surgical alternative to tracheotomy, expanded on the work of Ikematsu, who previously reported a surgical approach to alleviate snoring.3 As originally described and variously modified by subsequent authors, UPPP includes tonsillectomy in patients who have not previously undergone tonsillectomy. However, prior tonsillectomy does not preclude UPPP, which can then be performed by excision of mucosa which lines the tonsillar fossa after tonsillectomy. The anterior and posterior tonsillar pillars are trimmed, rotated across the tonsillar fossa, and applied to line the denuded fossa. The posterior margin of the soft palate and uvula are ablated. Modifications of the original surgical procedure substitute electrocautery and laser ablation for traditional surgical techniques.4
Technique UPPP is accomplished under general anesthesia. The patient is placed in the supine position with the neck slightly extended and the McIvar mouth gag is introduced to expose the oropharynx. When the patient has residual tonsils, UPPP should be accompanied by bilateral tonsillectomy. In either case, the anterior pillar is resected. I seek to resect approximately 1 cm of anterior pillar superiorly. This is tapered toward the junction of the anterior pillar and the tongue base inferiorly. Subsequent to this, the free edge of the soft palate is transected horizontally. Make an effort to develop a 90º angle between the vertical incision resecting the anterior pillar and the horizontal incision which resects the soft palate. The soft palate resection ordinarily removes approximately 1.2–1.4 cm of tissue measured at the narrowest spot (Figure 9.1). This includes complete amputation of the uvula. Hemostasis is achieved with electrocautery or suture ligature. Significant bleeding is rarely encountered. There does exist a small vessel in the midline of the uvula and another that enters the soft palate at the lateral aspect of soft palate. Both are easily controlled with electrocautery. When hemostasis is satisfactory, the posterior tonsil pillar is advanced and sutured to the
154
Uvulopalatopharyngoplasty
Figure 9.1 The UPPP is designed to resect approximately 1 cm of the anterior pillar and the free edge of the soft palate. The soft palate resection usually averages 1.2–1.4 cm of tissue.
Figure 9.2 The posterior tonsil pillar is mobilized laterally to close it with a suture to the residual oropharynx. The free edge of the soft palate is closed on itself.
residual oropharyngeal mucosa (Figure 9.2). The most critical and important stitch is the corner suture which serves to re-establish the shape of the oropharyngeal opening. This suture should be passed deeply enough to assure that it does not tear out. An over-andover technique seems to ensure this. A reabsorbable suture which stays in place for a minimum of 10 days prevents early dehiscence. It is essential that the surgeon use enough knots properly squared such that it does not untie in the first few postoperative hours due to swallowing and the moisture present in the oropharynx. Closure of the tonsillar pillars more inferiorly is elective. Lastly, the free edge of the soft palate is closed upon itself. An attempt is made to advance the nasopharyngeal mucosa to meet the oropharyngeal mucosa. This serves to promote healing and to ensure hemostasis. Postoperatively, patients are observed for a minimum of 3–4 h, subsequent to which the overwhelming majority can be discharged to home with instructions regarding diet and limitation of exercise. Most patients can tolerate only a soft, bland diet for the first week to 10 days. Attempts to drink too quickly are almost always associated with nasal emission. The majority of patients quickly accommodate to this, and nasal emission of fluids is rarely a problem beyond the first 10 days. Pain is controlled with an elixir containing acetominophen and a semisynthetic narcotic analgesic. Patients may ambulate, but are encouraged not to use the first few postoperative days as an opportunity to begin an exercise program.
Complications Hemorrhage following a tonsillectomy is a well-reported and understood complication. Its incidence should be no greater following
Results UPPP and tonsillectomy than following tonsillectomy alone. Most of the raw surfaces are closed following surgery for OSAS. The incidence of bleeding seems to be lower. Most patients lose 10–15 lb in the first 10 days following surgery. This is a reflection of the severity of their sore throat, and is welcomed in most instances. Nasal emission of fluid is an annoyance that rarely persists; however, a surgeon should be cautioned to resist excessive removal of soft palate. When the resection exposes the muscles of the soft palate, the risk of nasal emission goes up. The most dreaded complication of UPPP is the development of nasopharyngeal stenosis. This complication is almost always secondary to excessive removal of posterior pharyngeal tissue. The operator should never remove the posterior tonsillar pillars. Similarly, adenoidectomy should not be done with simultaneous UPPP. Under either circumstance, a circumferential wound is established which is the basis for scar contracture and the development of nasopharyngeal stenosis.
Results Mean short-term outcome data for UPPP are derived by meta-analysis of 37 case series, each of which reports on at least nine surgical subjects and assesses surgical outcomes through clear and unambiguous outcome measures, i.e. a pre- and postoperative polysomnogram (PSG).2 The mean decrease in apnea index (AI) in more than 500 patients was 55% from a mean preoperative AI of 45 apneas per hour. The mean decrease in respiratory (or apnea–hypopnea) index (RDI) in approximately 500 patients was 38% from a mean preoperative RDI of 60 apneas and hypopneas per hour. In 14 papers defining
155
surgical response as 50% decrease in AI, the reponse rate for 352 patients was 65%. In 16 papers defining surgical response by 50% decrease in RDI, the response rate for 375 patients was 53%. For 168 patients in nine reports, success was defined by the more restrictive and more recently applied criteria of: 50% decrease in AI to postoperative AI less than 10 apneas per hour, or 50% decrease in RDI to postoperative RDI less than 20 apneas and hypopneas per hour. Forty-three per cent of patients achieved success by the former definition, and 39% achieved success by the latter definition. If achievement of either of these criteria defines surgical success, 41% of patients respond to UPPP.2 There was no significant preoperative difference between responders and non-responders in terms of age, AI, RDI, minimum oxygen saturation, or body weight. Long-term follow-up is provided in a small number of studies. Fifty patients were followed for a mean of 46 months after UPPP. Six months postoperatively, 60% were responders (response defined by *50% reduction of preoperative RDI to less than 20 apneas and hypopneas per hour). Twenty-one months postoperatively, 39% of patients remained responders, relapse resulting from weight gain. Forty-six months postoperatively, 50% were classified responders. Weight loss, abstinence from alcohol and positional conditioning were cited in those who sustained late improvement.5 Twenty-five patients subjected to UPPP had a 6-month postoperative response rate of 64% (response defined by 50% decrease to postoperative RDI of less than 10) and a longterm (4–8 years postoperatively) response rate of 48%. No difference in preoperative RDI, body mass index (BMI), or change in BMI was found between long-term responders and nonresponders.6 Fifteen patients with response rate (response defined by greater than 50%
156
Uvulopalatopharyngoplasty
reduction in RDI) of 67% at 3–6 months postoperatively demonstrated a response rate of only 33% at greater than 5 years postoperatively (mean 88 months).7
Complications Early surgical complications compiled in a meta-analysis of 640 patients for whom complications were delineated included postoperative bleeding (1%), successfully managed perioperative upper airway obstruction (0.3%), and death secondary to upper airway obstruction (0.2%). Late complications are velopharyngeal insufficiency (VPI) of greater than 1 month in duration (2%), nasopharyngeal stenosis (1%), and voice change (1%). However, since more than half of the papers in the meta-analysis do not comment on complications, it is not possible to determine the true incidence of complications in the population.2 In two series which focused on complications of UPPP, the death rate for unsuccessfully managed upper airway obstruction was 1%.8,9 The incidence of postoperative VPI was dependent on the definition of VPI applied. The incidence of VPI 2 years after UPPP in 71 patients was: 39% with subclinical reflux of liquids apparent only on nasal endoscopy; 16% with nasal reflux when the patient bends over a water fountain to drink; 7% with subclinical nasal reflux, i.e. patient feels bubbles in the nose after drinking gaseous beverages; and 3% with ‘mild’ nasal reflux for liquids.10 Of 91 patients 1 year after UPPP, 31% reported persistent ‘dry throat’, while 10% reported ‘swallowing abnormalities’.9 A model of the upper airway in OSAS likens it to a simple collapsible tube. The tendency to collapse can be expressed quantitatively in terms of a critical pressure (Pcrit), the pressure surrounding the area of collapse. If atmospheric
pressure is designated zero, then airway collapse will occur whenever Pcrit is a positive number (indicating that it is higher than atmospheric pressure). Pcrit levels are higher during sleep than during wakefulness in both normal individuals and OSAS patients. This is the result of diminished tone in airway-supporting musculature. In normals, Pcrit rises from awake values that are more negative than –41 cmH2O to sleep values of –13 cmH2O.11–13 This means that, in normal individuals, atmospheric pressure is greater than Pcrit even during sleep, and the pharynx does not collapse. In OSAS patients, the spectrum of awake values of Pcrit is –40 to –17 cmH2O, and Pcrit during sleep is +2.5 cmH2O.11,12,14,15 Although the pharyngeal airway of awake OSAS patients tends to be more collapsible than that of awake normals, Pcrit does not cross the critical line of zero (i.e. atmospheric pressure) except when the individual with OSAS has sleep onset and OSAS results.11 Patients who have varying degrees of partial pharyngeal collapse have intermediate, but negative levels of Pcrit during sleep: –6.5 cmH2O for asymptomatic snorers, and –1.6 cmH2O for patients with hypopneas but no apneas.11,15 In general, Pcrit at values more negative than –5 cmH2O is associated with relief of sleepdisordered breathing.11 Examples of the decrement in Pcrit that are achieved by non-surgical interventions are –6 cmH2O through the loss of 15% of body weight, –3 to –4 cmH2O through protriptyline treatment, and –4 to –5 cmH2O through sleeping in a position other than supine.11 When 13 patients underwent UPPP, Pcrit decreased from a level of 0 to a level of –3 cmH2O. In those patients who had greater than 50% decrease in RDI in nonREM sleep, Pcrit decreased from –1 cmH2O to –7 cmH2O. The degree of improvement in sleep-disordered breathing was correlated
Results significantly with the change of Pcrit (p = 0.001), and the decrease in RDI was determined by the magnitude of the fall in Pcrit rather than by the initial level of Pcrit. No significant change in Pcrit was detected in nonresponders.16 Collapse of the pharynx during sleep occurs at a discrete (less than 1 cm) locus. Data derived from studies of the pharynx with awake endoscopy, awake endoscopy with Müller maneuver, asleep (drug-induced) endoscopy, asleep (natural and drug-induced) endoscopy with nasal continuous positive airway pressure (CPAP), asleep fluoroscopy, computed tomographic (CT) scan and manometry suggest that the pattern of static pharyngeal narrowing and/or dynamic pharyngeal collapse is localized and patient specific.16–18 Failure of UPPP may result from residual or secondary airway compromise at remote loci not surgically addressed. A model considers the pharynx as consisting of two loci: (1) retropalatal—located posterior to the soft palate; and (2) retrolingual—located posterior to the vertical portion of the tongue. The pharynx is preoperatively classified as follows: (1) type I—only the retropalatal region is compromised; (2) type II—both retropalatal and retrolingual regions are compromised; and (3) type III—only the retrolingual region is compromised.19 Association of pharyngeal type with UPPP outcome was accomplished by meta-analysis of UPPP outcomes in 168 patients in nine reports in which the preoperative pattern of pharyngeal narrowing or collapse was specified to be type I, II or III.2 Pharyngeal classification is achieved by application of one of the following techniques: awake fiberoptic endoscopy with or without Müller maneuver, asleep endoscopy with nasal CPAP, lateral cephalometry, airway manometry, or pharyngeal CT. For all patients (types I, II and III
157
combined), 43% achieved at least a 50% decrease in AI and postoperative AI less than 10 apneas and hypopneas per hour, and 39% achieved at least a 50% decrease in RDI and postoperative RDI of less than 20 apneas and hypopneas per hour. If achievement of either of these criteria defines surgical success, 41% of patients responded to UPPP.2 However, the mean percentage decrease in AI for type I was 75% (from a mean preoperative AI of 39 apneas per hour), while for types II and III, the mean percentage decrease in RDI was 23% (from a mean preoperative AI of 60 apneas and hypopneas per hour). The mean decrease in RDI for type I was 33% (from a mean preoperative RDI of 57 apneas and hypopneas per hour), while for types II and III the mean percentage decrease in RDI was 7% (from a mean preoperative RDI of 65 apneas and hypopneas per hour). The percentage of patients attaining at least 50% decrease in RDI to a postoperative RDI of less than 20 apneas and hypopneas per hour (or, alternatively, 50% decrease in AI to a postoperative AI of less than 10 apneas per hour, as reported in some papers), was 52% for type I patients and 5% for type II and type III patients.2 The variable degree of success of UPPP, which can be described in terms of change in AI, RDI or Pcrit, may reflect, at least in part, patient variability in upper airway anatomy and physiology. Patients classified as type I are more likely to have adequate change in parameters of success than those classified as type II or III. While UPPP diminishes the tendency for upper airway collapse in the retropalatal region, type II and III patients may continue to suffer collapse in the lower, or retrolingual, portion of the pharynx. This hypothesis is supported by data indicating salvage of patients who fail UPPP and subsequently undergo successful surgical
158
Uvulopalatopharyngoplasty
modification which alters the retrolingual region of the pharynx (lingual ablation, genioglossal advancement, hyoid myotomy and suspension, mandibular advancement, maxillo-mandibular advancement).2 However, even patients classified as type I have successful UPPP only 52% of the time. There are at least three alternative, though not mutually exclusive, explanations for this observation: (1) the techniques utilized to classify patients into types I, II and III are not sufficiently robust and periodically result in incorrect classification; (2) there are nuances of pharyngeal structure and function in patients correctly classified as type I which may mandate variable degrees of surgical modification at the palatal level (i.e. UPPP may not be an adequately robust surgical procedure to effectively treat all type I patients); and/or (3) there are nuances of pharyngeal structure and function in patients classified as type I which may mandate surgical modification at both the palatal and retrolingual levels (perhaps reflecting shift of the focus of pharyngeal collapse from retropalatal pre-UPPP to retrolingual post-UPPP). Support for all three explanations follows. Techniques utilized by clinicians to classify patients into types I, II and III have recognized limitations. Lateral cephalometry and fiberoptic endoscopy of the upper airway (with or without Müller maneuver) are the most widely applied techniques. Both are applied in the awake patient, while OSAS occurs in the sleeping patient under significantly different neurophysiologic conditions. Both are commonly applied in the seated patient, whereas the sleeping patient rarely assumes this position. Lateral cephalometry is adynamic and views the airway in only two dimensions, whereas airway collapse in OSAS is dynamic and occurs in three dimensions. While fiberoptic endoscopy offers the advantage of providing a
three-dimensional perspective, its intepretation is highly subjective. If the Müller maneuver is applied, the response may be confounded by the fact that the degree of negative pressure applied by the patient is not measured. Furthermore, the relationship between collapse of the awake pharynx challenged by the Müller maneuver and that of the passive pharynx in sleep remains in question. Indeed, different investigators describe varying degrees of success and failure in prognosticating UPPP outcome when fiberoptic endoscopy is used to preoperatively characterize the pharyngeal airway.2,20–22 Furthermore, studies comparing fiberoptic endoscopy with pharyngeal manometry, and other studies comparing either technique in wakefulness with the same technique applied in sleep, demonstrate disagreement in identifying pharyngeal dynamics.23–25 It has been demonstrated that nuances of pharyngeal structure and function in patients correctly classified as type I may mandate a degree of surgical modification at the palatal level beyond UPPP (i.e. UPPP may not be adequately robust for all type I patients). Transpalatal advancement pharyngoplasty (TPAP) is a procedure which enlarges the retropalatal airway by resection of the posterior hard palate and advancement of the soft palate, in an anterior direction, into the defect.26 It differs from UPPP, in which the hard palate is not altered. Sequential performance of UPPP and TPAP results in incremental decrease in Pcrit to a level below that resulting from UPPP alone. Four patients who underwent UPPP had a mean postoperative Pcrit of 5 cmH2O, a level at which OSAS would be expected to persist. TPAP increased the postUPPP retropalatal airway cross-sectional area by 321% (29 to 95 cm2, p < 0.01), and Pcrit was incrementally diminished to –4 cmH2O (p < 0.01).27
References It has been demonstrated that there are nuances of pharyngeal structure and function in patients classified as type I which may mandate surgical modification at both the retropalatal and retrolingual levels (possibly reflecting shift of the locus of pharyngeal collapse from retropalatal pre-UPPP to retrolingual post-UPPP). The shift of locus has been suggested by endoscopic and manometric analysis of the upper airway in wakefulness and sleep.23–25 The salvage of UPPP failures by surgical procedures which alter the retrolingual airway has previously been cited.2 The current perspective on surgery for OSAS regards UPPP as one component of the surgical armamentarium for OSAS. Airway vulnerability to collapse in OSAS is believed to involve different regions of the airway, and UPPP addresses primarily the retropalatal region. It is expected that UPPP will prove adequate for cure in only a fraction of patients. In the remainder, UPPP is applied in conjunction with other surgical modifications, either concomitantly or in stages. UPPP is applied when retropalatal narrowing is perceived to be a component of airway compromise. Other anatomic modifications are dictated when appraisal of the upper airway suggests retrolingual compromise. Review of the literature on UPPP reveals several deficiencies. Criteria for surgical success and failure have evolved over the two decades since Fujita’s introduction of UPPP. This evolution is reflected in the criteria for success applied in the succession of papers reviewed. Fujita established as the criterion for success a decrease in AI of at least 50% from its preoperative value. Current perceptions of the pathophysiology of OSAS mandate a more restrictive criterion for success, one that takes into account not only apneas but also hypopneas and subobstructive events that result in arousal. The ideal definition of response may require
159
development of a paradigm (applied preoperatively and postoperatively) which integrates parameters of sleep architecture, arousal and excessive daytime sleepiness with measures of respiratory disturbance and oxygenation. Such a complex descriptor of disease severity might be designed in a manner akin to the TNM tumor classification of the head and neck. Identification of which metrics and levels of severity best reflect thresholds of morbidity and mortality will be clarified by such investigations as the ongoing NIH Sleep Heart Health Study. However, the current lack of universal criteria for reporting results poses difficulty in interpretation and comparison of surgical as well as non-surgical outcomes. There are steps underway to standardize outcome reporting.28 Bias is frequently introduced into the surgical literature by retrospective study design and non-random loss to follow-up. The number of patients exposed to the surgical procedure often far exceeds the number having both preoperative and postoperative PSG. Studies are not randomized and generally do not have control groups. Sample size tends to be low, and statistical power is low. Missing data and missing and inconsistent definitions are common. Most papers report only short-term follow-up and infrequently report long-term follow-up. Few papers associate PSG data with patient-based assessment of quality of life.29
References 1. Fujita S, Conway W, Zorick F et al. Surgical correction of anatomical abnormalities in obstructive sleep apnea syndrome: uvulopalatopharyngoplasty. Otolaryngol Head Neck Surg 1981;89:923–34. 2. Sher AE, Schechtman KB, Piccirillo JF. The efficacy of surgical modifications of the upper
160
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
Uvulopalatopharyngoplasty
airway in adults with obstructive sleep apnea syndrome. Sleep 1996;19(2):156–77. Ikematsu T. Clinical study of snoring. 4th Report. Therapy [in Japanese]. J Jpn Otol Rhinol Laryngol Soc 1964;64:434–5. Ikematsu T, Simmons FB, Fairbanks DNF et al. Uvulopalato-pharyngoplasty: variations. In: Fairbanks DNF, Fujita S, eds. Snoring and Obstructive Sleep Apnea, 2nd edn. New York: Raven Press, 1994: 97–145. Larsson LH, Carlsson-Nordlander B, Ssvanborg E. Four-year follow-up after uvulopalatopharyngoplasty in 50 unselected patients with obstructive sleep apnea syndrome. Laryngoscope 1994;104:1362–8. Janson C, Gislason T, Bengtsson H et al. Long-term follow-up of patients with obstructive sleep apnea treated with uvulopalatopharyngoplasty. Arch Otolaryngol Head Neck Surg 1997;123: 257–62. Lu S-J, Chang S-Y, Shiao G-M. Comparison between short-term and long-term postoperative evaluation of sleep apnoea after uvulopalatopharyngoplasty. J Laryngol Otol 1995;109:308–12. Esclamado RM, Glenn MG, McCulloch TM et al. Perioperative complications and risk factors in the surgical treatment of obstructive sleep apnea syndrome. Laryngoscope 1989;99:1125–9. Haavisto L, Suonpaa J. Complications of uvulopalatopharyngoplasty. Clin Otolaryngol 1994;19:243–7. Zohar Y, Finkelstein Y, Talmi YP et al. Uvulopalatopharyngoplasty: evaluation of postoperative complications, sequelae, and results. Laryngoscope 1991;101:775–9. Winakur SJ, Smith PL, Schwartz AR. Pathophysiology and risk factors for obstructive sleep apnea. Semin Respir Crit Care Med 1998;19:999–1112. Suratt PM, Wilhoit SC, Cooper K. Induction of airway collapse with subatmospheric pressure in awake patients with sleep apnea. J Appl Physiol 1984;57:140–6.
13. Schwartz AR, Smith PL, Wise RA et al. Induction of upper airway occlusion in sleeping individuals with subatmospheric nasal pressure. J Appl Physiol 1988;64:535–42. 14. Horner RL, Mohiaddin RH, Lowell DG et al. Sites and sizes of fat deposits around the pharynx in obese patients with obstructive sleep apnoea and weight matched controls. Eur Respir J 1989;2:613–22. 15. Gleadhill IC, Schwartz AR, Schubert N et al. Upper airway collapsibility in snorers and in patients with obstructive hypopnea and apnea. Am Rev Respir Dis 1991;143: 1300–3. 16. Schwartz AR, Schiebert N, Rothman W et al. Effect of uvulopalatopharyngoplasty on upper airway collapsibility in obstructive sleep apnea. Am Rev Respir Dis 1992;145: 527–32. 17. Shepard JW Jr, Gefter WB, Guilleminault C et al. Evaluation of the upper airway in patients with obstructive sleep apnea. Sleep 1991;14(4): 361–71. 18. Launois SH, Feroah TR, Campbell WN et al. Site of pharyngeal narrowing predicts outcome of surgery for obstructive sleep apnea. Am Rev Respir Dis 1993;147:182–9. 19. Fujita S. Midline laser glossectomy with lingualplasty: a treatment of sleep apnea syndrome. Op Tech Otolaryngol Head Neck Surg 1991;2:127–31. 20. Aboussouan LS, Golish JA, Wood BG et al. Dynamic pharyngoscopy in predicting outcome of uvulopalatopharyngoplasty for moderate and severe obstructive sleep apnea. Chest 1995;107:946–51. 21. Doghramji K, Jabourian ZH, Pilla M et al. Predictors of outcome for uvulopalatopharyngoplasty. Laryngoscope 1995;105:311–14. 22. Petri N, Suadicani P, Wildschiodtz G et al. Predictive value of Muller maneuver, cephalometry and clinical features for the outcome of uvulopalatopharyngoplasty. Acta Otolaryngol (Stockh) 1994;114:565–75.
References 23. Woodson BT, Wooten MR. Comparison of upper airway evaluation during wakefulness and sleep. Laryngoscope 1994;104:821–8. 24. Woodson BT, Wooten MR. Manometric and endoscopic localization of airway obstruction after uvulopalatopharyngoplasty. Otolaryngol Head Neck Surg 1994;111:38–43. 25. Skatvedt O. Localization of site of obstruction in snorers and patients with obstructive sleep apnea syndrome: a comparison of fiberoptic nasopharyngoscopy and pressure measurements. Acta Otolaryngol (Stockh) 1993;113:206–9. 26. Woodson BT, Toohill RJ. Transpalatal advancement pharyngoplasty for obstructive sleep apnea. Laryngoscope 1993;103: 269–76.
161
27. Woodson BT. Retropalatal airway characteristics in uvulopalatopharyngoplasty compared with transpalatal advancement pharyngoplasty. Laryngoscope 1997;107:735–40. 28. American Academy of Sleep Medicine Task Force on Sleep Related Breathing Disorders in Adults. Recommendations for syndrome definition and measurement techniques in clinical research. Sleep 1999;5:667–89. 29. Schechtman KB, Sher AE, Piccirillo JF. Methodological and statistical problems in sleep apnea research: the literature on uvulopalatopharyngoplasty. Sleep 1995;18(8):659–66.
10 Laser uvulopalatoplasty B Tucker Woodson
There are many treatment options available for sleep-disordered breathing (SDB) and obstructive sleep apnea (OSA). These include positional therapy, weight loss, medical treatment of underlying or predisposing conditions, devices, and surgery. The primary treatment of OSA is nasal continuous positive airway pressure (CPAP). Oral appliances and surgery are alternatives for the treatment of OSA and are also primary treatments for snoring. Surgical treatment, when successful, may correct some of the structural etiologies of the disorders. This chapter describes laserassisted uvulopalatoplasty (LAUP) as a surgical treatment option. There are three features of a ‘ideal’ surgery for OSA syndrome. These include: (1) low morbidity; (2) minimal cost; and (3) demonstrated clinical effectiveness.1 LAUP achieves the first two of these three criteria. The third and most important (i.e. effectiveness) remains uncertain. Most individuals agree that acute perioperative morbidity and the serious complication rate of LAUP are low. LAUP’s direct costs are relatively low compared to other surgical procedures. The controversy over effectiveness will be answered only from critically reviewed outcome studies. This chapter will attempt to address important concepts and to describe the current status of the medical literature relating to LAUP.
Therapeutic goals for OSA are to ‘cure’ the disorder, eliminate symptoms, and reduce the risk of sequelae from the disease. Currently, there are no true ‘cures’ of the disorder. Successful treatments reduce obstructive events and symptoms to a subclinical level. Following successful surgery, patients do not require the daily compliance that other modalities require. However, on which outcomes do we assess successful treatment? The symptoms which form the primary focus of surgery are snoring and excessive daytime sleepiness. Hypertension, increased risks of stroke and cardiovascular disease and increased risk of mortality are the medical sequelae associated with OSA.2–4 Successful treatment should reduce these risks. No LAUP studies have addressed these outcomes. Most data on LAUP address only symptomatic outcomes, with snoring as the most common symptom reported. Effectiveness on sleepiness is infrequently noted. Only a few studies report objective respiratory data, which are crucial to assess effectiveness for LAUP. Better outcome data on LAUP are needed. The needed prospective randomized studies are difficult to perform. The current understanding of LAUP’s effectiveness often comes from uncontrolled retrospective case series. Conclusions from these studies must be guarded.
164
Laser uvulopalatoplasty
An additional goal of surgery is to reconstruct the airway. Successful snoring surgery reduces vibration and flutter. Successful apnea surgery reduces upper airway obstruction and airflow limitation during sleep. LAUP’s effect on airflow limitation and airway obstruction are yet to be determined. Since it is not possible to completely re-evaluate every new and minor modification of a surgical procedure, assessment of LAUP effectiveness at this time must be based on available clinical studies, extrapolated data from similar procedures, and our understanding of the pathophysiology of SDB and the upper airway. Kamami proposed LAUP in 1991 as a treatment for snoring.5 Subsequently, the procedure has been advocated and applied to treat OSA.6,7 The clinical application of LAUP was rapid following use for snoring, was done prior to any systematic study, and resulted in controversy. The American Sleep Disorders Association (ASDA) published an initial position paper with reservations on the procedure until adequate published data established its safety and efficacy.8 This position has not been significantly altered, although LAUP has been demonstrated as a safe outpatient, ambulatory procedure.9 Nonetheless, LAUP remains controversial, because data on efficacy are still sparse. Few procedures in otolaryngology and sleep medicine have created such polarity, with such distinct advocates and critics.
Background It is generally accepted that palatal operations are the most common procedures used to treat SDB and OSA. The two most common palatal operations performed have been uvulopalatopharyngoplasty (UPPP) and LAUP. Historically, both were developed to treat snoring.
The success rate in treating snoring is high. Each reports an 80% success rate.5,10 Both procedures have been empirically applied to treat OSA. Successful outcomes for OSA have been much lower than outcomes for snoring. Prior to LAUP and even before the description of OSA, Ikamatsu described palatopharyngoplasty to reduce snoring.11 Ikamatsu’s development was spurred by the clinical observation of redundant pharyngeal tissues in snorers. By modification and removal of tissues of the uvula, palate, and pharynx, snoring was reduced in many individuals without impairing swallowing or speech. Similar observations of redundant tissues in apneic patients by Fujita led him to modify UPPP to treat OSA.12 Although success was only partial, UPPP provided an alternative to tracheotomy.13 LAUP was first described by Kamami in 1991 as a treatment for snoring. The development of LAUP was, in part, spurred by the advent of surgical technologies, which created widely available office-based carbon dioxide lasers. The carbon dioxide laser enabled hemostatic removal and ablation of mucosa and soft tissue. This could be performed with only local anesthesia in an outpatient or office-based setting without the need for inpatient hospitalization. LAUP has several characteristics that differentiate it from traditional UPPP. Initial descriptions of LAUP were as a staged serial procedure. This was in contrast to UPPP, which was done in a single operative setting. LAUP’s tissue ablation centered chiefly on the palate, velum, and uvula. As first described, LAUP was a palatoplasty and not a pharyngoplasty. Finally, the intention of LAUP is to heal by secondary intent. This contrasted to UPPP, which created palatal flaps that were advanced and closed primarily using sutures. Kamami’s first LAUP technique involved using a CO2 laser to create two vertical trenches in the soft palate. These were lateral
Background to the uvula and extended approximately 1 cm from the free margin of the distal soft palate. The trenches were then widened and the uvula narrowed and shortened (but not removed). The wound then healed secondarily. Clinically,
165
shortening of the palate and uvula was observed. Procedures were then repeated as needed. Although each procedure removed only a small amount of tissue, repeated sessions created additive effects.
A
B
C
Figure 10.1 Techniques of laser-assisted uvulopalatoplasty (LAUP) are depicted. All may be performed under local anesthesia. The technique of Kamami is depicted in the upper level (A). Parallel trenches lateral to the uvular muscle are created and the uvula shortened by approximately 50%. A modified ‘UPPP technique’ is shown in the middle level (B). Lateral trenches are widened, and more aggressive removal of the uvula is performed. In the lower level (C), the mucosal stripping technique is depicted. The uvula is excised (cross-hatch) and midline palatal mucosa is removed down to muscle (stripes).
166
Laser uvulopalatoplasty
Multiple modifications have been proposed for LAUP since its inception. Tissue ablation with LAUP is not limited to the palate but may involve the tonsillar pillars and pharynx.14 Variations include but are not limited to complete or partial removal of the uvula, aggressive widening of lateral trenches in the palate, or even distal excision of the palate similar to UPPP (Figure 10.1). The procedure is not limited to the CO2 laser but may be performed using other types of lasers or any tool that will remove or ablate tissue while also providing adequate hemostasis.15 Considering this wide array of techniques, the term ‘LAUP’ is applied to a series of procedures all of which trace their development to the initial descriptions by Kamami. The procedures must have the following characteristics: (1) the capability of being repeatedly performed; (2) it must surgically modify the uvula and soft palate; and (3) healing must be by secondary intention. Alternatively, single-stage pharyngoplasties that are sutured primarily are considered to be modifications of techniques initially described by Fujita (i.e. UPPP). It is speculated but unproven that multiple LAUP procedures may modify the upper airway commensurately with other palatopharyngoplasty techniques. An additive effect is suggested by a progressive snoring reduction demonstrated with successive procedures.16 However, additive effectiveness in reducing OSA has not been demonstrated. A major dilemma in performing LAUP is the criterion used to identify a treatment endpoint. As a snoring procedure, the endpoint of treatment was determined with resolution of patient’s self-reports of snoring, the loss of the ability of the patient to ‘snort’, or the development of side-effects such as temporary velopharyngeal incompetence.17 For snoring, these criteria are adequate; however, for OSA, the presence or absence of snoring is a
questionable endpoint. It is well established that snoring may be eliminated in patients following LAUP and UPPP with persistent obstructive apnea.7,13 The current standard method of determining surgical endpoint uses snoring reduction, elimination of voluntary snorting or new onset of velopharyngeal dysfunction as the outcomes to stop treatment. None of these is demonstrated as related to objective OSA outcomes, yet their use continues.
Advantages and disadvantages of LAUP LAUP has several real and potential advantages over more conventional techniques. Because the CO2 laser may cut, ablate and coagulate the tissues, the procedure is readily adaptable to an ambulatory office-based setting. LAUP may be performed under local anesthesia without the need for sedation, general anesthesia, or an operating room environment. There is no hospitalization required. This is significantly different from UPPP, where few if any patients are treated in the office. This lowers the risk to the patient and the potential cost of the procedure. In addition, the incidence of velopharyngeal dysfunction is low. Presumably this is because, as LAUP is a serial procedure, tissue removal is less. The procedure is terminated with appearance of velopharyngeal dysfunction. Surgery can be slowly ‘titrated’ to the needs of the patient as an alternative to a ‘one-step’ UPPP. LAUP was marketed as a procedure causing little pain compared to traditional surgeries. However, when objectively compared, LAUP and UPPP pain are similar.18 Both are associ-
Advantages and disadvantages of LAUP ated with severe pain. Based on a 10-point visual analog scale, peak pain rated near 10 in studies reporting pain (7.7 and 10). Peak pain occurred from day 2 to day 7, and varied by surgeon and likely patient. No method of pain control has been demonstrated to be superior. A claim of less pain appears not to have been substantiated. However, LAUP pain may be variable. Successive procedures cause less pain than the first. Even if pain is severe, most patients are treated ambulantly with little or no time off work. Side-effects and complications of LAUP are usually minor or infrequent. Dysphagia, velopharyngeal insufficiency and minor bleed-
167
ing are uncommon following LAUP.9,19,20 Severe bleeding requiring hospitalization or transfusion is rare. General anesthesia is rarely required for LAUP. Time off work is minimal. Disadvantages of LAUP include concerns about effectiveness for OSA, severe pain associated with the procedure, and worries about treating patients in a non-observed postoperative environment. Is OSA worsened? Acutely, it is. Terris et al demonstrated that LAUP worsened respiratory disturbance index (RDI), but did not significantly narrow the retropalatal airway as measured postoperatively with MRI.21 Postoperative RDI doubled and lowest oxygen saturation decreased.
Frontal
A
BA
B
A
B
A
B
Velum
A
B
Base
C
Figure 10.2 The pattern of healing following traditional LAUP. Following LAUP, palatal trenches are created and the uvula shortened (A). With healing, the trenches close. This shortens the distance between points A and B, and creates lateral tension in the palate. The uvula is observed to retract (B). The effects on the nasopharynx are variable, but trenches in the palate (red) reduce the circumference of the pharyngeal isthmus. This may narrow the velopharyngeal area (C).
168
A
C
Laser uvulopalatoplasty
Vertical palate
B
D
Because of these concerns, most authors who use LAUP to treat OSA recommend the perioperative use of nasal CPAP following LAUP procedures. With this recommendation, perioperative respiratory complications appear to be rare following LAUP.22 The long-term effects of LAUP are unknown. Palatal scarring occurs after the procedure.23,24 This initially increases tension and reduces snoring (Figure 10.2). Airway narrowing may or may not occur. If airway narrowing does occur, the potential decrease in collapsibility due to decreased compliance may be lost, with softening of scar tissue that occurs over 12–24 months.24 This would worsen apnea (Figure 10.3). Extensive thermal damage created by the laser also damages all three layers of the soft palate and may result in chronic inflammation, ulceration, and loss of seromucinous glands. The latter may
Figure 10.3 A nasopharyngeal view of the velopharyngeal inlet open (A) and narrowed (C) as occurs during partial airway collapse. Note that the narrowest portion of the pharyngeal isthmus is at the velopharyngeal inlet. With palatal resection, the velopharyngeal inlet is moved rostrally. In the vertically oriented velum (D), a shorter palate will have little effect on upper airway size. In the more horizontally oriented velum (B), palate shortening may increase area size.
explain common complaints of pharyngeal dryness after LAUP.23
Complications The complication rate of LAUP is low. Complications may be grouped as acute surgical, perioperative, or late. Acute complications may include hemorrhage, anesthetic reaction, vasovagal reactions, aspiration, laser burn, or damage to teeth.5,6,9,25–28 Unpublished reports indicate that these may occur in less than 1% of patients. Bleeding requiring local cautery is not common, with reports of 1–1.2% incidence. Perioperative reports indicate that bleeding acutely or in the first 7–10 days is uncommon. Minor bleeding not requiring treatment may occur in 2–3% of patients.
Pharyngeal anatomy Severe bleeding is rare, with many large series not reporting this complication and smaller series reporting a 1% bleeding rate requiring treatment. Infection may be underreported (0.5–3% infection rate), since criteria may vary among surgeons. Acute velopharyngeal symptoms (either nasal reflux or speech-related velopharyngeal insufficiency (VPI)) are variable. Symptoms were reported in 10–14% in one series (29 patients); however, larger series have reported only 0–0.5% temporary VPI or nasal reflux.28,29 Long-term VPI that requires further treatment is rare and virtually unreported. Lesser degrees of dysfunction have not been systemically evaluated. The most common complication and complaint following LAUP is the sensation of a dry throat or thickened mucus. The prevalence of this ranges from 12% to 21%.28,29 The etiology of this is unclear. It may result from impaired mucociliary clearance, scarring, pharyngeal paresthesia, pharyngeal phantom sensation, loss of the uvula, actual changes in mucus production, or other unknown causes. Treatment is often difficult. In summary, LAUP’s advocates cite the advantages of local anesthesia, low complication rates and lower costs in an ambulant setting. Critics cite the lack of objective data supporting the effectiveness of the procedure for OSA, the cost of the laser, and the significant perioperative pain.
Pharyngeal anatomy LAUP’s goal is to modify the pharyngeal valve for OSA in order to augment patency while not impairing speech and swallowing. Critical sites of airway obstruction and the effects of LAUP are unknown. Increasing pharyngeal airway stability may be achieved by increasing airway size, decreasing airway compliance, or altering
169
Nose Flow Hard palate Soft palate
Mouth
Figure 10.4 Airflow and pressure drops across a flowlimiting collapsible airway segment release kinetic energy, which results in vibration and flutter of soft tissues. The primary source of vibratory snoring is the soft palate. The severity of flutter and vibration is a function of the length of the soft palate, the compliance of the soft tissues, and the pressure drop across the flow-limiting segment.
upper airway shape. The defining feature of obstruction is airflow limitation. Airflow limitation is dependent not only on the size of the airway but also on the airway’s compliance and shape, the pressure drop across the segment, surface tension forces, inspiratory effort, Bernoulli forces, and airway length.30 Increasing airway size and decreasing airway collapsibility are important. Modifying collapsing or critical closing pressures are associated with and may even predict UPPP success or failure.30,31 Which aspects of LAUP technique best modify the upper airway are unknown. The actual mechanisms of snoring are complex and are only partially understood (Figure 10.4) Snoring is reduced or altered by several potential mechanisms. The noise of snoring results from flutter and vibration of
170
Laser uvulopalatoplasty
the uvula, soft palate and tissues of the pharyngeal lateral wall bands.32 The flutter and noise frequency is determined by tissue elasticity and palatal length.33 The pressure drops across the flow-limiting segments drives snoring by releasing kinetic energy. The combination of increased airway resistance and compliance, and increased negative inspiratory pressure, determine the pressure drop across the flow-limiting segment. Surgery affects snoring by stiffening or shortening tissues of the palate or pharynx or alternatively by reducing airflow limitation or ventilatory effort. Precisely which mechanism is effective in LAUP patients is unknown. Several different pharyngeal shapes have been described. Finkelstein et al classified the upper pharynx into flat or circular types (Figure 10.5). Studies of airway shape in OSA also describe a third type with a narrow
A
B
C
Figure 10.5 Patterns of pharyngeal collapse. The coronal type (A) is closed in an anterior–posterior direction. Circular airways (B) are physiologically most stable. Theoretically, circular airways offer the least resistance to airflow for any given cross-sectional area. (C) A sagittal pattern of collapse may occur from contributions of the lateral pharyngeal wall.
oropharynx.34,35 Therefore, the three general shapes of the pharyngeal segment include: (1) a coronally shaped velopharynx which is flat in an anterior–posterior dimension, with its long axis lying in the coronal plane; (2) a circular pharynx; and (3) a sagittal oropharynx with its long axis oriented in the sagittal plane. Closure in the coronal pharynx is often in the anterior–posterior dimension. Closure in the sagittal pharynx may be circular or result predominantly from movement of the lateral pharyngeal walls to the midline. Collapse of the lateral pharyngeal walls may result from hypertrophy of the lateral walls or from tonsillar hypertrophy. The adult pharyngeal airway is phylogenetically unique among mammals. Instead of being tightly interdigitated to the skull base, the larynx in humans descends into the neck.36 In contrast to other mammals and infants, the adult human upper airway is composed of a significant supralaryngeal soft tissue pharynx. The patency of this pharynx is maintained by the activity of pharyngeal dilator muscles.37 A loss of muscle tone during sleep places the pharynx at risk of partial or complete obstruction. Since patients with OSA syndrome have smaller and more compliant upper airways, they are predisposed to airway collapse.38,39 No single abnormality defines OSA or SDB. The common denominator is a small airway size (Figure 10.6). Many variables contribute to an abnormal upper airway involving both the facial skeleton and soft tissues.40,41 Findings associated with this segment in OSA syndrome include a long and wide soft palate. Often, there is enlargement of the uvula, and there may be webbing of palatal mucosa. Collapse of the lateral pharyngeal walls contributes to both OSA and snoring. The size and thickness of the lateral walls are increased in OSA compared to normals.42 In addition, the pharyngeal airway may be encroached
Pharyngeal anatomy
171
2
Normal OSA
Cross-sectional area
1
3
Tensor palatini Levator palatini Palatoglossus Palatopharyngeus
0
10
20
30
40
50
60
70
Airway length from hard palate (mm)
Figure 10.6 The cross-sectional airway size measured from the hard palate inferiorly is shown in normals and in patients with OSA. For both groups, the smallest pharyngeal segment is 10 mm below the hard palate, in the area of the pharyngeal isthmus. With loss of muscle tone or with increased negative inspiratory pressures, this segment is most vulnerable to collapse.
upon by enlargement of surrounding pharyngeal musculature. This includes the palatopharyngeus, stylopharyngeus, and prevertebral muscles. Maxillary retrusion compromises the pharyngeal isthmus anteriorly. Abnormalities of the upper cervical vertebrae may compromise the segment posteriorly. The segment most vulnerable to collapse is the pharyngeal isthmus bordered by the soft palate and uvula anteriorly, lateral pharyngeal walls laterally,
4
Figure 10.7 The actions of the tensor palatini (1), levator palatini (2), palatoglossus (3) and palatopharyngeus (4). Muscular shortening or anatomic shortening of the levator palatini muscle may result in posterior and superior movement of the velum, closing the airway.
and nasopharyngeal wall posteriorly.43 This is the area altered by LAUP. Muscles comprising the velum include the tensor and levator veli palatini, musculus uvulae, palatopharyngeus, palatoglossus, superior, middle and inferior constrictors, stylopharyngeus, and salpingopharyngeus.44 Most of the physiologic actions of the pharyngeal muscles narrow the pharynx. The variable effects of LAUP may result from differing anatomy. Muscles ablated during LAUP may include the musculus uvulae, palatopharyngeus, palatoglossus, and levator veli palatini. The musculus uvulae’s physiologic functions are to add bulk to the palate, increasing its thickness, and to elevate the palate. Shortening of the levator veli palatini elevates and posteriorly displaces the velum (Figure 10.7). Muscle shortening also
172
Laser uvulopalatoplasty
moves the lateral walls medially. The palatopharyngeus adducts the posterior tonsillar pillars, constricts the pharyngeal isthmus, narrows the velopharynx, and elevates the larynx. Finally, the palatoglossus muscle pulls the tongue postero-superiorly and constricts the oropharynx at the anterior tonsillar pillars. The palatoglossus also lowers and tenses the velum. The combined effect of surgically modifying these muscles is unknown but
conceptually may be either beneficial or detrimental, depending on the underlying anatomy. During the LAUP procedure, muscle is both excised and damaged. This is followed by scarring, contracture, and shortening. If anatomic shortening parallels the action of physiologic shortening, constriction and pharyngeal narrowing may occur with laser ablation. If extreme, stenosis may result (Figure 10.8).
44 4 4
4
4
2
2
1
1
2 1
3
A
3
2 1
33 3 3
B
Figure 10.8 The effects of shortening of the palatopharyngeus (A) and palatoglossus (B) are shown in a coronal plane. Shortening of the muscles closes the oropharyngeal and the pharyngeal isthmus. Muscles may also act as dilators, depending on the muscle resting position during contraction. When the pharynx is closed, contraction of both muscles will dilate the airway. When the pharynx is wide open, contraction of muscles will constrict the airway.
Patient selection
173
Figure 10.9 A mechanism for creating pharyngeal stenosis with excision of lateral wall tissues. Removal of mucosa posterior to the fold of the posterior tonsillar pillar reduces lateral pharyngeal wall width. Since the pharynx is fixed posteriorly, lateral shortening must result in posterior displacement of the palate and pharyngeal folds.
Another mechanism of LAUP’s effect is to modify the myomucosal envelope. By contracture and scarring of the mucosa, the underlying shape and configuration of the pharynx may be modified. This modification is the mechanism of effect of palatal stripping procedures. Basic science studies have demonstrated that tensile forces in the palate are increased following palatal stripping.25 Excessive removal of mucosa may also worsen the upper airway structure. A major risk of stenosis occurs when lateral pharyngeal wall mucosa is excised. Damage to this vulnerable strip of mucosa has long been recognized as a cause of nasopharyngeal stenosis following tonsillectomy and adenoidectomy (Figure 10.9). Finkelstein et al45 have raised troubling concerns about the possible effects of LAUP on postoperative upper airway structure. In a non-randomized study of patients before and after LAUP and UPPP, oropharyngeal configuration was measured with photographs. A small sample was also measured postoperatively with cephalometric X-rays. Although the photographs were not quantitative, both LAUP techniques used in the study created oropharyngeal stenosis. Quantitative measures of airway size following UPPP (when scar
contracture may presumably be less) were much larger than following LAUP. Both of these results must be evaluated with caution, since preoperative selection may have biased postoperative outcomes. However, the possibility of anatomic stricture is real following LAUP.
Patient selection No consensus exists in selecting patients for LAUP. Contraindications for the procedure include significant tonsillar hypertrophy, an excessive gag reflex, or obstruction at nonpalatal locations in the upper airway. Patients with clinically significant nasal obstruction should have this corrected prior to LAUP. Patients with clinically significant OSA and inability to use nasal CPAP following surgical procedures should probably have other procedures performed, or have LAUP performed with intensive postoperative monitoring for respiratory complications. Indications for LAUP vary. All would agree that patients undergoing LAUP should be informed that its effectiveness has not been
174
Laser uvulopalatoplasty
determined. Attempts to identify and exclude patients with non-palatal levels of airway obstruction should be made. This may include physical examination, endoscopy using Müller’s maneuver, cephalometric X-rays, sedated endoscopy, or manometry during sleep. Several authors have proposed that body mass index (BMI) discriminates patient responders from non-responders. Improved outcomes of snoring subjects have been observed in patients with a BMI below 25–28 kg/m2.46 This is in contrast to OSA outcomes, where BMI did not discriminate responders from non-responders.28,29 Paradoxically, although almost all authors use Müller’s maneuver to select patients for LAUP, patient response by level of collapse on endoscopic Müller’s maneuver did not differ in OSA patients.27 Cephalometric X-rays have been evaluated in several studies. Utley et al47 did not observe differences in success in a small number of patients. However, using digital fluoroscopy, Tsushima et al48 classified good and poor LAUP responders. Hyoid bone position was more inferiorly displaced and postoperative posterior airspace was smaller in non-responder groups. Different outcomes in these studies may reflect small sample groups, different criteria used to define success, and differences in other non-controlled demographics. Level of obstruction during sleep has been evaluated manometrically by Skadtvelt.49 Although high success rates were observed with this technique, other groups have failed to improve surgical success using similar techniques.50 Also, Skadtvelt’s LAUP surgical technique may actually represent UPPP performed with the laser rather than LAUP. Application of results to more traditional LAUP techniques may not be valid. Optimism about using manometry to select LAUP patients must be tempered. Treatment response based on apnea severity has been variable. Some authors have had
higher success rates with less severe OSA measured by either RDI or AI.7,26–28 Other authors have not observed significant differences in success dependent on OSA severity. In summary, no current consensus exists on selecting patients for LAUP. Lacking such a consensus, LAUP should be applied conservatively. Those patients with the highest probability of success are probably non-obese, with mild OSA and a predominant complaint of snoring. All patients with OSA require postoperative sleep testing following the procedure to assess effectiveness. These studies need to be performed at least 6 weeks following surgery and after body weight has stabilized. Owing to the frequent changes in BMI that occur following surgery, a 3–6 month equilibration period is probably of benefit prior to obtaining a postoperative polysomnogram.
LAUP techniques Several LAUP techniques have been described. Few have been objectively evaluated or compared.15,25,29 No one technique is ‘better’ than another. Individual surgeons have preferences based on their experience. The choice of technique may vary with anatomy, levels of obstruction, and severity of disease. No accepted scheme or classification of LAUP has been widely applied. Techniques, however, may be classified into three types. These include the ‘French’ technique of Kamami, with serial uvula resection along with simultaneous palatal trenches to shorten the palate, the ‘palatal excision’ technique, with uvula resection, excision of distal palate, and midline ‘mucosal stripping’. Studies suggesting airway stenosis with use of the palatal trench technique are worrisome (Figure 10.10).45 If such stenosis were to occur, OSA could be
LAUP techniques
175
A
Figure 10.10 Two different configurations of the palatopharyngeus muscle. When anteriorly placed and vertically oriented, scarring and shortening of the palatopharyngeus muscle results in stiffening of the palate without a change in airway size. When obliquely oriented, scarring and shortening of this muscle will result in narrowing of the pharynx.
B
C worsened in some patients. In fact, the failure of studies using the palatal trench technique to show statistically significant improvement is consistent with a hypothesis that some patients may have worsened sleep apnea. It may be noteworthy that those studies suggesting statistical improvement in groups of patients undergoing LAUP have used the ‘UPPP’-type technique. Obviously, there are inadequate data to compare studies or techniques (Figures 10.11 and 10.12).
Figure 10.11 Preoperative (A), postoperative (B) and longterm postoperative (C) photographs of a traditional LAUP procedure with conservative removal of tissue. There is marked medialization of the posterior pillar and palatopharyngeus muscle. This is consistent with anatomic shortening of the muscle. No significant change in position of the anterior tonsillar pillar is seen.
176
Laser uvulopalatoplasty
B
A Figure 10.12 A more aggressive LAUP with widening of the lateral trenches is shown (A). With a UPPP-type procedure, the uvula may be completely amputated. After healing, the uvula has retracted (B) and there has been a significant medialization of the anterior pillars. Scarring of the palate may result in less vibration and flutter, affecting the noise of snoring. LAUP’s effects on the airway are dependent on the underlying anatomy as well as surgical technique.
LAUP overview
LAUP for snoring
A review of the English language surgical literature has identified 35 papers published with results presented on nine patients or more. The majority of these papers address snoring as an outcome. Data on physiologic outcomes such as respiratory events, daytime functioning, blood pressure and other cardiovascular effects are severely lacking. Some data have been presented comparing different LAUP techniques. However, the combined literature does present considerable evidence on complications associated with LAUP. Based on this literature review, LAUP may treat both snoring and OSA; however, a definitive statement of effectiveness cannot be made. Since only some patients respond successfully to the treatment, improved patient evaluation and selection may improve outcomes. Methods to identify optimal candidates have yet to be established.
In the non-apneic population, snoring is common. It is also the cardinal symptom of OSA and is often the OSA patient’s presenting complaint. The severity of snoring may not always relate to the patient’s complaint of sleepiness or OSA. Furthermore, snoring is often minimized by the medical establishment as being cosmetic. Yet, multiple studies associate snoring with both cardiovascular risk and sleepiness independent of OSA. When watching the sleep of a stentorian snorer, common sense dictates that neither health nor sleep are well served. Clearly, not all snoring is pathologic. However, successful treatment of nonapneic ‘benign’ snorers often results in dramatic effects on social functioning, sleep, and general health. In cases where more conservative treatments have not been successful, surgical treatment of snoring is medically indicated.
LAUP for obstructive sleep apnea A key problem in treating snoring is having a consensus on the definition of snoring itself. Snoring may be defined as an objectionable noise that results from vibration and flutter of the pharynx during sleep. Snoring, therefore, has two components: noise and objectionable complaints. Controversy exists as to which component should be measured when evaluating snoring outcomes. There is also uncertainty as to which should be used as an endpoint of surgical treatment. A patient who has a major change in noise amplitude, yet continues to have complaints of snoring, will require further treatment. In this case, a successful objective measure would be a clinical failure. Alternatively, a patient with only a minor change in the overall amplitude and quality of the snoring noise but who has the complaints eliminated would neither seek nor require further treatment. This would be an objective failure but a clinical success. Therefore, although the noise of snoring is critical, its simple amplitude does not truly define ‘clinical’ snoring. Acoustics analysis before and after LAUP demonstrates small changes in snoring peak amplitude. Distribution of the snoring frequency does change. A major change is the shift of snoring fundamental frequencies to higher and presumably less bothersome sounds.51 Such a change in snoring intensity and frequency has also been correlated with a shifting of the anatomic location of the pressure drop that occurs with snoring. Frequency is higher and amplitude is lower when obstruction occurs at the tongue base and tonsils.52 Data from Hoffstein et al53 indicate that there is very little agreement between objectively measured snoring sounds and snoring complaints. There is also little agreement between different observers and the nature of snoring sounds. It appears that snoring is almost individually defined and a very
177
personal complaint. Therefore, defining snoring using solely objective criteria will continue to be elusive.
LAUP for obstructive sleep apnea LAUP has demonstrated effects on both subjective and objective outcomes for OSA. A consensus on LAUP’s effectiveness remains controversial, due to significant gaps in the medical literature. Problems include a lack of consistent outcome measures, large numbers of patients lost to follow-up, and retrospective case series. Furthermore, patient selection criteria and LAUP surgical techniques are often poorly described. This makes extrapolating findings to other patient populations difficult.6,7,15,20,22,26–28,47–49,54,55 Surprisingly, little has changed since the initial ASDA position paper on LAUP was published in 1994.8,56 One of the biggest obstacles to interpreting LAUP results continues to be the large numbers of patients who are lost to followup. When only a small number of patients are available for follow-up, data presented may not represent the overall population studied. The burden of proof rests on the advocates of the procedure, and no studies have adequately addressed this. Many reasons may explain poor polysomnographic followup. Patients are reluctant to pursue further treatment due to prior treatment failure and/or severe pain. They perceive the test as bothersome and an academic exercise if their primary complaint of snoring has been resolved. Last, out-of-pocket costs may deter some patients. Discrepancy in LAUP results may reflect the different techniques used. The best outcomes
178
Laser uvulopalatoplasty
of LAUP were reported by Mickelson and Pribitkin using a UPPP variant of LAUP. This contrasts with studies using a trench technique, where statistically significant results have not been obtained. Multiple variables may confound the results of the studies. One variable that may influence studies is that many patients’ preoperative polysomnograms pre-date LAUP by a considerable time. Walker et al noted that polysomnograms pre-date LAUP by over 18 months.7 Since data suggest the potential of significant worsening of OSA over this time frame, LAUP results may be skewed to miss a possible treatment effect. A recent well done prospective study demonstrated 30% success but also 30% worsening (>100% increase) after LAUP.57 LAUP improves subjective outcome. Excessive daytime sleepiness has improved with both visual analog measures and Epworth Sleepiness Scales. In a small number of patients who only underwent LAUP for OSA, multiple sleep latency test improved from 5–10 min.28
LAUP future directions As an ambulatory procedure, LAUP may be performed under local anesthesia, at a relatively low cost. LAUP, if effective, would have potential advantages over UPPP; both in lower cost and lower complication rates. Unfortunately, this has not been established, and randomized trials measuring relevant outcomes are required. Since LAUP may worsen OSA, it should be performed with caution until questions are answered.
References 1. Powell N, Riley R, Troell R et al. Radiofrequency volumetric reduction of the tongue. Chest, 1997;111:1348–55.
2. Hla K, Young T, Bidwell T et al. Sleep apnea and hypertension. Ann Intern Med 1994;120:382–8. 3. Hung J, Whitford E, Parsons R et al. Association of sleep apnoea with myocardial infarction in men. Lancet 1990;336:261–4. 4. He J, Kryger M, Zorick F et al. Mortality and apnea index in obstructive sleep apnea: experience in 385 male patients. Chest 1988;94(1):9–14. 5. Kamami Y. Outpatient treatment of snoring with CO2 laser: laser-assisted UPPP. J Otolaryngol 1994;23(6):391–4. 6. Kamami Y. Outpatient treatment of sleep apnea syndrome with CO2 laser: laser-assisted UPPP. J Otolaryngol 1994;23(6): 395–8. 7. Walker R, Grigg-Damberger M, Gopalsami C. Laser-assisted uvulopalatoplasty for snoring and obstructive sleep apnea: results in 170 patients. Laryngoscope 1995;105:938–43. 8. Standards of Practice Committee of the American Sleep Disorders Association. Practice parameters for the use of laser assisted uvulopalatoplasty. Sleep 1994;17:744–8. 9. Walker R, Gopalsami C. Laser-assisted uvulopalatoplasty: postoperative complications. Laryngoscope 1996;106:834–8. 10. Gtontved A, Jorgensen K, Petersen S. Results of uvulopalatopharyngoplasty in snoring. Acta Otolaryngol 1992;492(Suppl):11–14. 11. Ikamatsu T. Palatopharyngoplasty and partial uvulectomy method of Ikematsu: a 30 year clinical study of snoring. In: Fairbanks D, Fujita S, Ikematsu T, Simmons FB, eds. Snoring and Sleep Apnea. 1st edn. New York: Rivlin Press, 1987: 130–4. 12. Fujita S, Conway W, Zorick F et al. Surgical correction of anatomic abnormalities of obstructive sleep apnea syndrome: uvulopalatopharyngoplasty. Otolaryngol Head Neck Surg 1981;89:923–34. 13. Fujita S, Conway WA, Zorick FJ et al. Evaluation of the effectiveness of the
References
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
uvulopalatopharyngoplasty. Laryngoscope 1985;95:70–4. Krespi Y, Pearlman S, Keidar A. Laserassisted uvula-palatoplasty for snoring. J Otolaryngol 1994;23(5):328–34. Hanada T, Furuta S, Tateyama T et al. Laserassisted uvulopalatoplasty with Nd:YAG laser for sleep disorders. Laryngoscope 1996;106:1531–3. Coleman J. Laser-assisted uvulopalatoplasty: long-term results with a treatment for snoring. Ear Nose Throat J 1998;77(1):22–34. Coleman J, Rathfoot C. Oropharyngeal surgery in the management of upper airway obstruction during sleep. Otolaryngol Clin North Am 1999;32:263–75. Clarke R, Yardley M, Davies C et al. Palatoplasty for snoring: a randomized controlled trial of three surgical methods. Otolaryngol Head Neck Surg 1998;119:288–92. Cheng D, Chih-Ming Weng J, Yang P. Carbon dioxide laser surgery for snoring: results in 192 patients. Otolaryngol Head Neck Surg 1998;118:486–9. Dickson R, Mintz D. One-stage laser-assisted uvulopalatoplasty. J Otolaryngol 1996;25(3):155–161. Terris D, Clerk A, Norbash A et al. Characteristics of postoperative edema following laser-assisted uvulopalatoplasty using MRI and polysomnography: implications for the outpatient treatment of obstructive sleep apnea syndrome. Laryngoscope 1996;106:124–8. Walker R, Grigg-Damberger M, Gopalsami C. Laser-assisted uvulopalatoplasty for the treatment of mild, moderate, and severe obstructive sleep apnea. Laryngoscope 1999;109:79–85. Berger G, Finkelstein Y, Ophir D. Histopathologic changes of the soft palate after laser-assisted uvulopalatoplasty. Arch Otolaryngol Head Neck Surg 1999;125:786–90.
179
24. Courey M, Fomin D, Smith T et al. Histologic and physiologic effects of electrocautery, CO2 laser, and radiofrequency injury in the porcine soft palate. Laryngoscope 1999;109:1316–19. 25. Kotecha B, Paun S, Leong P et al. Laser assisted uvulopalatoplasty: an objective evaluation of the technique and results. Clin Otolaryngol 1998;23:354–9. 26. Lauretano A, Khosla R, Richardson G et al. Efficacy of laser-assisted uvulopalatoplasty. Lasers Surg Med 1997;21:109–16. 27. Mickelson S, Ahuja A. Short-term objective and long-term subjective results of laserassisted uvulopalatoplasty for obstructive sleep apnea. Laryngoscope 1999;109:362–7. 28. Pribitkin E, Schutte S, Keane W et al. Efficacy of laser-assisted uvulopalatoplasty in obstructive sleep apnea. Otolaryngol Head Neck Surg 1998;119:643–7. 29. Ingrams D, Spraggs P, Pringle M et al. CO2 laser palatoplasty: early results. J Laryngol Otol 1996;110:754–6. 30. Isono S, Akiko S, Tanaka A et al. Efficacy of endoscopic static pressure/area assessment of the passive pharynx in predicting uvulopalatopharyngoplasty outcomes. Laryngoscope 1999;109:769–74. 31. Schwartz A, Schubert N, Rothman W et al. Effect of uvulopalatopharyngoplasty on upper airway collapsibility in obstructive sleep apnea. Am Rev Respir Dis 1992;145:527–32. 32. Liistro G, Stanescu D, Veriter C et al. Pattern of snoring in obstructive sleep apnea patients and heavy snorers. Sleep 1991;14:517–25. 33. Huang L. Mechanical modeling of palatal snoring. J Acoust Soc Am 1995;97(6):3642–8. 34. Finkelstein Y, Talmi Y, Nachmani A et al. On the variability of velopharyngeal valve anatomy and function: a combined peroral and nasoendoscopic study. Plastic Reconstructive Surg 1992;89(4):631–9. 35. Schwab R, Gupta K, Gefter W et al. Upper airway and soft tissue anatomy in normal subjects and patients with sleep-disordered
180
36.
37. 38.
39.
40.
41.
42.
43.
44.
45.
46.
Laser uvulopalatoplasty
breathing. Significance of the lateral pharyngeal walls. Am J Respir Crit Care Med 1995;152:1673–89. Laitman J, Reidenberg J. Specializations of the human upper respiratory and upper digestive systems as seen through comparative and developmental anatomy. Dysphagia 1993;8:318–25. White D. Pathophysiology of obstructive sleep apnoea. Thorax 1995;50:797–805. Isono S, Remmers J, Tanaka A et al. Anatomy of the pharynx in patients with obstructive sleep apnea and in normal subjects. J Appl Physiol 1997;82:1319–26. Gleadhill I, Schwartz A, Schubert N et al. Upper airway collapsibility in snorers and in patients with obstructive hypopnea and apnea. Am Rev Respir Dis 1991;143:1300–3. Lyberg T, Krogstad O, Djupesland G. Cephalometric analysis in patients with obstructive sleep apnoea syndrome: skeletal morphology. J Laryngol Otol 1989;103: 287–292. Lyberg T, Krogstad O, Djupesland G. Cephalometric analysis in patients with obstructive sleep apnoea syndrome: soft tissue morphology. J Laryngol Otol 1989;103: 293–7. Caballero P, Alvarez-Sala R, Garcia-Rio F. CT in the evaluation of the upper airway in healthy subjects and in patients with obstructive sleep apnea syndrome. Chest 1998;113:111–16. Morrison D, Launois S, Isono S et al. Pharyngeal narrowing and closing pressures in patients with obstructive sleep apnea. Am Rev Respir Dis 1993;148:606–11. McWilliams B, Morris H, Shelton R. The nature of the velopharyngeal mechanisms. In: McWilliams BJ, ed. Cleft Palate Speech. 2nd edn. St Louis: Mosby, 1990: 197–235. Finkelstein Y, Shapiro-Feinberg M, Stein G et al. Uvulopalatopharyngoplasty vs laserassisted uvulopalatoplasty. Arch Otolaryngol Head Neck Surg 1997;123:265–76. Rollheim J, Miljeteig H, Osnes T. Body mass index less than 28 kg/m2 is a predictor of
47.
48.
49.
50.
51.
52.
53.
54.
55.
subjective improvement after laser-assisted uvulopalatoplasty for snoring. Laryngoscope, 1999;109:411–14. Utley D, Shin E, Clerk A et al. A cost-effective and rational surgical approach to patients with snoring, upper airway resistance syndrome, or obstructive sleep apnea syndrome. Laryngoscope 1997;107:726–34. Tsushima Y, Antila J, Laurikainen E et al. Digital fluoroscopy before and after laser uvulopalatopharyngoplasty in obstructive sleep apnea: importance of pharyngeal collapsibility and hyoid bone position. Acta Radiol 1997;38:214–21. Skatvedt O, Akre H, Godtlibsen OB. Continuous pressure measurements in the evaluation of patients for laser assisted uvulopalatoplasty. Eur Arch Otorhinolaryngol 1996;253:390–4. Hudgel D, Harasick T, Katz R et al. Uvulopalatopharyngoplasty in obstructive apnea: value of preoperative localization of site of upper airway narrowing during sleep. Am Rev Respir Dis 1991;143:942–6. Walker R, Gatti W, Piorier N et al. Objective assessment of snoring before and after laserassisted uvulopalatopharyngoplasty. Laryngoscope 1996;106:1372–7. Miyazaki S, Itasaka Y, Ishikawa K et al. Acoustic analysis of snoring and the site of airway obstruction in sleep related respiratory disorders. Acta Otolaryngol 1998;S537:47–51. Hoffstein V, Mateika S, Nash S. Comparing perceptions and measurements of snoring. Sleep 1996;783–9. Walker R, Garrity T, Chellam G. Early polysomnographic findings and long-term subjective results in sleep apnea patients treated with laser-assisted uvulopalatopharyngoplasty. Laryngoscope 1999;109:1438–41. Walker R, Grigg-Damberger M, Gopalsami C. Uvulopalatopharyngoplasty versus laserassisted uvulopalatoplasty for the treatment of obstructive sleep apnea. Laryngoscope 1997;107:76–82.
References 56. Littner M, Kushida CA, Martse K et al. Practice parameters for the use of laborassisted uvulopalatoplasty: an update for 2000. Sleep 2001;24:603–19.
181
57. Ryan CF, Love LL. Unpredictable results of laser assisted uvulopalatoplasty in the treatment of obstructive sleep apnea. Thorax 2000;55:399–404.
11 Hypopharyngeal airway surgery Kasey K Li and Nelson B Powell
Introduction Hypopharyngeal obstruction is a major contributing factor in obstructive sleep apnea (OSA). Hypopharyngeal obstruction stems from the prominence or relaxation of the base of the tongue, and lateral pharyngeal wall collapse, and occasionally involves the aryepiglottic folds or epiglottis.1–3 ‘Disproportionate’ skeletal anatomy in the form of a narrowed mandibular arch and/or mandibular deficiency can also be a significant factor leading to hypopharyngeal obstruction.4 The complex interplay of the soft and hard tissues that contribute to hypopharyngeal obstruction, the importance of the hypopharynx to speech and swallowing, as well as the subsequent edematous response after surgical intervention, present a formidable challenge to the sleep surgeon. The Stanford Surgical Protocol incorporates a conservative, stepwise treatment philosophy along with a risk management strategy to minimize the risks of surgery. This protocol has been refined and modified since we first described the mandibular advancement procedure for the treatment of hypopharyngeal obstruction in 1983.5
Rationale for hypopharyngeal surgery Hypopharyngeal obstruction has been documented in OSA by EMG studies, cephalometric radiography, CT scanning, MRI and videofluoroscopy.3,6–9 These diagnostic studies have improved our understanding of the mechanism of hypopharyngeal obstruction, in that it can result from the prominence or collapse of the base of the tongue, lateral pharyngeal wall, the aryepiglottic folds or epiglottis, as well as the disproportionate mandibular anatomy. Tracheotomy was the first treatment to manage OSA in ‘Pickwickian’ subjects. Tracheotomy is a highly effective therapy in the management of hypopharyngeal obstruction, as it bypasses this region completely. Since the first tracheotomy performed by Kuhlo et al,10 various procedures have been developed to improve airway obstruction in the hypopharynx (Table 11.1). These procedures were developed based on the understanding of the anatomy and physiology of the maxillofacial skeletal relationships and the genioglossus–hyoid complex as they relate to airway size during wakefulness and sleep. Since these surgical approaches were
184
Hypopharyngeal airway surgery
Table 11.1 Surgical procedures for treatment at the hypopharyngeal region. Mandibular osteotomy with genioglossus advancement Hyoid myotomy with suspension Maxillomandibular advancement Tongue base resection Tracheotomy (bypass all upper airway obstructions) Radiofrequency volumetric reductiona Electrical stimulationb Suture to tongue basec a b
c
New technology with multi-center studies in progress. Experimental and investigational with studies in progress. New technology with studies in progress.
specifically designed to alleviate hypopharyngeal obstruction, accurate presurgical evaluations are essential for the appreciation of the anatomic abnormality present. This allows for the utilization of a surgical protocol that results in improved clinical outcomes. At our center, a thorough head and neck evaluation combined with fiberoptic pharyngolaryngoscopy is performed to isolate and direct treatment at the region or regions of obstruction. A lateral cephalometric radiograph is also utilized to assist in treatment planning. Although cephalometric radiography is only a static two-dimensional method of evaluating a dynamic three-dimensional area, it does provide useful information on the posterior airway space. The posterior airway space measurement on lateral cephalometric radiographs has been shown to correlate with the volume of hypopharyngeal airway on three-dimensional CT scans.11 In addition, it is a valuable study to assess the relationship of
N
S
Ba PNS ANS A P PAS
Go B
MP H Gn
Figure 11.1 Cephalometric analysis. The normative values are as follows: SNA 82˚ (SD ± 2), maxilla to cranial base; SNB 80˚ (SD ± 2), mandible to cranial base; PAS 11 mm (SD ± 1), posterior airway space; PNS–P 37 mm (SD ± 3), length of soft palate; MP–H 15.4 mm (SD ± 3), distance of hyoid from inferior mandible. Ba, basion; Gn, gnathion; Go, gonion; ANS, anterior nasal spine; PNS, posterior nasal spine.
the maxillofacial skeleton and the hyoid bone with the airway (Figure 11.1).
Stanford protocol The Stanford two-phase surgical protocol (Figure 11.2) combines the evaluation, the indications for treatment, and the treatment philosophies to manage upper airway obstruction in OSA. This two-phase approach was
Stanford protocol Presurgical evaluation (physical examination, cephalometric analysis, fiberoptic pharyngoscopy)
Phase I (site of obstruction)
UPPP (type 1 oropharynx)
UPPP + GAHM (type 2 oropharynx – hypopharynx) (Type
GAHM (type 3 hypopharynx)
Postoperative polysomnogram (6 months) (failure)
185
Figure 11.2 The Stanford protocol. UPPP, uvulopalatopharyngo plasty; MMA, maxillomandibular advancement; GAHM, genioglossus advancement/hyoid myotomy.
Phase II MMA
Table 11.2 Criteria for cure. Postsurgical RDI and LSAT equal to CPAP results For patients without CPAP results Postsurgical RDI of 20 or less and at least a reduction of RDI by 50%, i.e. an RDI of 26 would need to be reduced to 13 Postsurgical SaO2 must be normal or with only a few brief falls below 90% Normalization of sleep architecture Subjective complaints of EDS neutralized RDI, respiratory disturbance index; CPAP, continuous positive airway pressure; EDS, excessive daytime sleepiness; LSAT, lowest oxygen saturation.
established to minimize surgical interventions and avoid unnecessary surgery while achieving a cure. After the completion of phase I surgery, patients are allowed a period of healing for 4–6 months, and a postoperative polysomnogram is obtained to evaluate outcome. Since continuous positive airway pressure (CPAP) is considered the ‘gold standard’ treatment
modality, we have instituted a surgical goal to define cure (Table 11.2). This strict criterion enables us to compare our surgical results with CPAP results. Patients with persistent OSA following phase I surgery are offered phase II surgery (maxillomandibular advancement). Clearly, not all of the patients undergo phase I surgery prior to phase II surgery. Patients with severe OSA and significant mandibular deficiency, or patients who have already undergone uvulopalatopharyngoplasty (UPPP) may proceed directly to phase II surgery. Therefore, it is important to review all possible treatment options and explain the rationale for upper airway reconstruction. In our opinion, combining phase I and phase II surgery should be avoided due to the potential for unnecessary surgery, as well as the increased surgical morbidity and postoperative airway compromise. Our concern for postoperative airway compromise has prompted us to further establish a CPAP surgical protocol.12 Nasal CPAP is prescribed 2 weeks prior to surgery in patients with a respiratory disturbance index (RDI) greater than or equal to 40 and oxygen desaturation of 80%
186
Hypopharyngeal airway surgery
or less. The patients are maintained on CPAP postoperatively until 2 weeks prior to the postoperative polysomnogram (4–6 months). In patients with severe OSA (RDI > 60 and SaO2 < 60%), temporary tracheotomy is considered.
Phase I surgery Since the mandible, tongue and hyoid complex are major determinants of the airway dimension at the hypopharyngeal level,4,13 mandibular osteotomy with genioglossus advancement and hyoid myotomy and suspension have evolved for the reconstruction of this region. Anterior repositioning of the genioglossus muscle is achieved through a conservative mandibular osteotomy that advances the genial tubercle without movement of the teeth or mandible. It improves the tension of the genioglossus muscle and decreases its collapsibility during sleep, thus alleviating airway obstruction. The rationale for altering the hyoid position in the treatment of tongue base obstruction is the fact that, anatomically, the hyoid complex is an integral part of the hypopharynx. Anterior movement of the hyoid complex improves the posterior airway space, and numerous reports have supported the concept that surgical intervention at the hyoid level improves the hypopharyngeal airway.14–17 In 1984, we described the inferior mandibular osteotomy with hyoid myotomy and suspension for hypopharyngeal reconstruction.18 The technique has evolved over the years to improve outcome and minimize morbidity. The current technique of mandibular osteotomy with genioglossus advancement involves a limited osteotomy intraorally to isolate and advance the genial tubercle. It is a
minimally invasive procedure that is routinely completed within 30 min. Although hyoid myotomy with suspension also improves hypopharyngeal obstruction and is included in the phase I surgical protocol, it is not always performed simultaneously with genioglossus advancement. This is because the majority of patients with OSA have diffuse airway obstruction, and genioglossus advancement is generally combined with UPPP. The added insult to the infrahyoid region by combining the genioglossus advancement and hyoid myotomy and suspension results in increased edema, and was thought to be inappropriate in some patients. We have also found that the hypopharyngeal airway obstruction is resolved with only genioglossus advancement in some patients, so a hyoid procedure may not always be necessary. Furthermore, in some elderly patients (> 60 years old), airway edema following simultaneous genioglossus advancement and hyoid myotomy and suspension can result in prolonged dysphagia that may require days to resolve. For these reasons, we perform hyoid myotomy and suspension only in some patients as a separate surgical step.
Surgical procedures Mandibular osteotomy with genioglossus advancement The operation is designed to reposition the genial tubercle forward, thus improving the tension of the tongue musculature and limiting its posterior displacement during sleep. The limiting factor in this forward movement is the thickness of the mandibular symphysis.
Surgical procedures Preoperative radiographic analysis, including a lateral cephalometric radiograph and a panoramic dental X-ray, is necessary to assist the surgeon in surgical planning. The cephalometric radiograph will document skeletal deformities and soft tissue airway narrowing. It will further assist in the evaluation of the genial tubercle position and the airway changes following surgery. The panoramic radiograph will demonstrate the course of the inferior alveolar nerve canal, the mental foramen, and the position of the mandibular tooth roots, as well as detect potential pathologic processes of the mandible. The procedure begins with a mucosal incision approximately 7–8 mm below the mucogingival junction. A subperiosteal dissection is performed to expose the mandibular symphysis. The genial tubercle and genioglossus muscle can be identified by finger palpation in the floor of the mouth and with the aid of the lateral cephalometric radiograph. It is recommended that the superior horizontal bone cut be at least 5 mm below the mandibular root apices to decrease the likelihood of tooth paresthesia. The inferior horizontal bone cut should be designed to preserve approximately 10 mm of the inferior border of the mandible to reduce the risk of a pathologic mandibular fracture. The lateral and vertical bone cuts should be within the confines of the canine roots. Prior to completing the osteotomy, a titanium screw is placed in the outer cortex in order to manipulate the genial tubercle fragment. Bleeding is controlled with electrocautery and a hemostatic agent such as Gelfoam® (Pharmacia and Upjohn Company, Kalamazoo, Michigan, USA). The fragment is advanced and rotated 60–90º to prevent retraction back into the floor of the mouth. The outer cortex and marrow are removed and the inner cortex is rigidly fixed with a lag screw (Figure 11.3).
187
A
B Figure 11.3 The mandibular osteotomy with genioglossus advancement procedure. (A) Anterior view. (B) Lateral view.
Hyoid myotomy and suspension Our initial hyoid procedure involved the suspension of the hyoid to the mandible.18 We have modified the procedure several times in an attempt to minimize surgical trauma. The current hyoid myotomy and suspension technique involves suspending the hyoid to the superior thyroid cartilage (Figure 11.4).19 We
188
Hypopharyngeal airway surgery Figure 11.4 The hyoid myotomy and suspension procedure.
have found that the current technique is less invasive and the results have been comparable to those of the earlier procedures. The current hyoid myotomy and suspension is approached with a horizontal skin incision made over the hyoid bone. Surgical dissection is performed through the suprahyoid musculature to the body of the hyoid bone. The infrahyoid and suprahyoid muscles are partially dissected off the body of the hyoid bone to allow mobilization of the hyoid complex. Occasionally, the stylohyoid ligament may need to be released from the lesser cornu to improve the degree of mobilization. Limiting the dissection within the lesser cornu will minimize the risk of superior laryngeal nerve injury. The hyoid is secured to the superior thyroid cartilage with four permanent sutures. A passive surgical drain is placed for 1–2 days to prevent seroma or hematoma formation.
Perioperative management Patients with OSA have an increased risk for postoperative airway compromise. As stated
earlier, nasal CPAP should be attempted at least 2 weeks prior to surgery to reverse sleep debt and prevent REM rebound in the postoperative period. Anesthesia induction and intubation should be performed with the surgeons present. In patients with a difficult airway, especially in obese patients with an increased neck circumference (> 46 cm) and associated skeletal deformities (mandibular deficiency and low hyoid bone), an awake fiberoptic intubation or tracheotomy should be considered.20 All patients should be extubated awake in the operating room immediately following surgery. Intensive care unit (ICU) monitoring should be considered in patients undergoing multiple procedures (UPPP combined with genioglossus advancement and/or hyoid myotomy and suspension), or in patients with significant coexisting medical problems such as hypertension and coronary artery disease. Nasal CPAP or humidified oxygen (35%) via face tent should be used on all patients, and oximetry monitoring is performed throughout the hospitalization. Blood pressure should be monitored closely, and hypertension treated aggressively with intravenous antihypertensive medications
Phase II surgery to minimize postoperative bleeding and edema. The use of narcotics should be closely monitored due to the increased potential for airway compromise.21,22 Our protocol consists of intravenous morphine sulfate (MS) or meperidine HCl administered by a nurse in graduated doses (e.g. MS 1–8 mg every 1–3 h as necessary) in the ICU while monitoring respiratory rate, oxygen saturation and mental status. Intramuscular meperidine HCl and oxycodone elixir are used after the patients are transferred to the floor on the second postoperative day. Oral hydrocodone is used following discharge. Patients are discharged if there is a stable airway, adequate oral intake of fluids, and satisfactory pain control. The use of nasal CPAP is recommended after discharge, and humidified oxygen is prescribed for 2 weeks in patients with severe OSA syndrome who cannot tolerate nasal CPAP.
Phase I surgical protocol clinical outcomes Our surgical results were reported in 1992 (Table 11.3).23 Two hundred and thirty-nine patients underwent phase I surgery, with most of the patients requiring intervention at the pharyngeal and hypopharyngeal levels. The overall cure rate was 61% (145/239 patients). The surgical results were comparable to nasal CPAP results. The mean preoperative RDI was 48.3, and the mean postoperative RDI 9.5 (nasal CPAP RDI 7.2, p = NS). The lowest oxygenation saturation (LSAT) improved from 75% to 86.6% (nasal CPAP LSAT 86.4%, p = NS). There was a higher cure rate with mild to moderately severe disease (approximately 70%) as compared to severe
189
disease (42%). Most of the patients who failed phase I therapy had severe OSA (mean RDI 61.9) and morbid obesity (mean body mass index (BMI) 32.3 kg/m2). The postoperative morbidity was low. The mean hospital stay was 2.1 days. The complications associated with genioglossus advancement and hyoid suspension were infection (< 2%), injury of tooth roots requiring root canal therapy (< 1%), permanent paresthesia and anesthesia of the mandibular incisors (< 6%), and seroma (< 2%). Major complications such as mandibular fracture, alteration of speech, alteration of swallow or aspiration were not encountered.
Phase II surgery Craniomaxillofacial skeletal abnormality is a well-recognized predictor in OSA.1,24,25 Many patients with OSA have maxillomandibular deficiency resulting in diminished airway size that leads to nocturnal obstruction. In 1983, we reported the use of mandibular advancement surgery in the treatment of OSA.5 The forward movement of the mandible improved hypopharyngeal obstruction. We subsequently investigated the effect of maxillomandibular advancement (MMA) on the airway and have utilized this procedure as the second phase of our surgical protocol.26 MMA achieves enlargement of the pharyngeal and hypopharyngeal airway by physically expanding the skeletal framework. In addition, the forward movement of the maxillomandibular complex improves the tension and collapsibility of the suprahyoid and velopharyngeal musculature. The majority of patients who entered the phase II surgical protocol had completed the phase I protocol and had failed to respond fully. These patients had already
190
Hypopharyngeal airway surgery
undergone reconstruction of the airway at the nasal, pharyngeal and hypopharyngeal levels. Phase I surgical failure usually involves persistent obstruction of the hypopharyngeal level (occasionally combined with pharyngeal-level obstruction). The MMA procedure creates further tension and physical room in the upper airway, relieving residual obstructions. In order to maximize airway expansion, a major advancement of the maxillomandibular complex is required to facilitate a successful result. However, it is important to achieve maximal advancement while maintaining a stable dental occlusion and a balanced esthetic appearance. Over the past 17 years, patients with and without ‘disproportionate’ craniomaxillofacial features have undergone MMA for persistent severe OSA due to incomplete response to phase I surgery. Although patients with craniomaxillofacial abnormalities such as maxillary and/or mandibular deficiencies usually have improved facial esthetics following surgery, we found that many patients with normal cephalometric measurements preoperatively also have an improved facial appearance following MMA. This is because many of our patients are middle-aged adults who are already showing signs of facial aging due to soft tissue sagging. Skeletal expansion of the maxilla and mandible enhances appearance by improving soft tissue support.
Phase II surgical protocol clinical outcomes An analysis of 175 patients between 1988 and 1995 demonstrated that 166 patients had a successful outcome, with a cure rate of 95% (Table 11.4). The mean preoperative RDI was 72.3. The mean postoperative RDI was 7.2. The surgical results were comparable to nasal
Table 11.3 Surgical protocol results: phase I.
Surgery groups
Patient success/ total patients
Success rate (%)
GAHM + UPPP GAHM UPPP Total
133/223 4/6 8/10 145/239
60 66 80 61
Table 11.4 Surgical outcomes, phase II—MMA.
Surgery groups Failed phase I Skeletal deformity (without UPPP) Failed UPPPa Total a
Patient success/ total patients
Success rate (%)
83/86 10/11
97 91
73/78 166/175
94 95
Outside referral—severe OSA syndrome.
CPAP results (nasal CPAP RDI 8.2, p = NS). The mean LSAT improved from 64.0% to 86.7% (nasal CPAP LSAT 87.5%, p = NS). Eighty-six patients who failed the phase I surgical protocol underwent MMA. The mean age of patients was 43.5 years. The cure rate in this group was 97% (83/86 patients). Most of the patients who failed the phase I protocol but declined MMA were older, with a mean age of 51.8 years. The mean hospital stay was 2.4 days. The surgical morbidity included transient anesthesia of the lower lip, chin and cheek in all of the patients. There was an 87% resolution between 6 and 12 months. There was no postoperative
References bleeding or infection. Mild malocclusion encountered in some patients was treated satisfactorily with dental occlusal adjustment. No major skeletal relapse occurred. To date, 59 patients (49 men) have had long term follow-up results. The mean age was 47.1 years. The mean BMI was 31.1 kg/m2. Nineteen patients had only subjective (quality of life) results. These patients refused long-term polysomnograpy for various reasons, including inconvenience, time and cost. Sixteen of the 19 patients continued to report subjective success with minimal to no snoring, no observed apnea, and no recurrence of excessive daytime sleepiness (EDS). All patients reported stable (unchanged) weight to mild weight gain (< 5 kg). Three patients reported recurrence of snoring and excessive daytime sleepiness (EDS). Long-term polysomnographic data were available in 40 patients (33 men). The mean age was 45.6 years. The mean BMI was 31.4 kg/m2. The preoperative RDI and LSAT were 71.2 and 67.5%, respectively. The 6-month postoperative RDI was 9.3 and the LSAT was 85.6%. The mean follow-up period was 50.7 months, and long-term RDI and LSAT were 7.6 and 86.3%, respectively. The mean weight at the long-term follow-up was 32.2 kg/m2 (p = 0.002). Four patients had recurrent OSA. The 6-month RDI in these four patients was 10.5, but the longterm RDI (61 ± 24.7 months) was 43.0. The LSAT decreased from 87.5% to 81.8%.
Conclusion A systematic and conservative approach to the management of hypopharyngeal airway obstruction has been described. The surgical techniques have been modified and refined over the past 17 years. A thorough presurgical evaluation to identify airway collapse is
191
mandatory to allow for the utilization of the Stanford protocol, which results in improved clinical outcomes. This logical stepwise surgical approach in airway reconstruction will minimize surgical interventions and avoid unnecessary operations. The incorporation of the risk management protocol will minimize treatment complications.
References 1. Riley RW, Guilleminault C, Powell NB et al. Palatopharyngoplasty failure, cephalometric roentgenograms, and obstructive sleep apnea. Otolaryngol Head Neck Surg 1985;93:240–4. 2. Kletzker GR, Bastian RW. Acquired airway obstruction from histologically normal, abnormally mobile supraglottic soft tissues. Laryngoscope 1990;100:375–9. 3. Schwab RJ, Gefter WB, Hoffman EA. Dynamic upper airway imaging during awake respiration in normal subjects and patients with sleep-disordered breathing. Am Rev Respir Dis 1993;148:1385–400. 4. Rojewski TE, Schuller DE, Clark RW et al. Videoendoscopic determination of the mechanism of obstruction in obstructive sleep apnea. Otolaryngol Head Neck Surg 1984;92:127–31. 5. Powell N, Guilleminault C, Riley R, Smith L. Mandibular advancement and obstructive sleep apnea syndrome. Bull Eur Physiopathol Respir 1983;19:607–10. 6. Remmers JE, deGroot WJ, Sauerland EK, Anch AM. Pathogenesis of upper airway occlusion during sleep. J Appl Physiol 1978;44:931–8. 7. Riley R, Powell N, Guilleminault C. Cephalometric roentgenograms and computerized tomographic scans in obstructive sleep apnea. Sleep 1986;9:514–15.
192
Hypopharyngeal airway surgery
8. Suratt PM, Dee P, Atkinson RL et al. Fluoroscopic and computed tomographic features of the pharyngeal airway in obstructive sleep apnea. Am Rev Respir Dis 1983;127:487–92. 9. Shepard JW, Thawley SE. Evaluation of the upper airway by computerized tomography in patients undergoing uvulopalatopharyngoplasty for obstructive sleep apnea. Am Rev Respir Dis 1989;140:711–16. 10. Kuhlo W, Doll E, Franck MD. Erfolgreiche Behandlung eines Pickwick Syndroms durch eine Dauertrachekanuele. Dtsch Med Wochenschr 1969;94:1286–90. 11. Riley RW, Powell NB. Maxillofacial surgery and obstructive sleep apnea syndrome. Otolaryngol Clin North Am 1990;23:809–26. 12. Powell N, Riley R, Guilleminault C. Obstructive sleep apnea, continuous positive airway pressure, and surgery. Otolaryngol Head Neck Surg 1988;99:362–9. 13. Lowe A, Gionhaku N, Tadeuchi K et al. Three dimensional reconstructions of the tongue and airway in adult subjects with obstructive sleep apnea. Am J Orthodont 1986;90:364–74. 14. Kaya N. Sectioning the hyoid bone as a therapeutic approach for obstructive sleep apnea. Sleep 1984;7:77–8. 15. Van de Graaf WB, Gottfried SB, Mitra J et al. Respiratory function of hyoid muscles and hyoid arch. J Appl Physiol 1984;57:197–204. 16. Patton TJ, Thawley SE, Water RC et al. Expansion hyoid-plasty: a potential surgical procedure designed for selected patients with obstructive sleep apnea syndrome. Experimental canine results. Laryngoscope 1983;93:1387–96. 17. Patton TJ, Ogura JH, Thawley SE. Expansion hyoidplasty. Otolaryngol Head Neck Surg 1984;92:509–19.
18. Riley RW, Guilleminault C, Powell NB, Derman S. Mandibular osteotomy and hyoid bone advancement for obstructive sleep apnea: a case report. Sleep 1984;7:79–82. 19. Riley RW, Powell NB, Guilleminault C. Obstructive sleep apnea and the hyoid: a revised surgical procedure. Otolaryngol Head Neck Surg 1994;111:717–21. 20. Riley RW, Powell NB, Guilleminault C, Pelayo R, Treoll RJ, Li KK. Obstructive sleep apnea surgery: risk management and complications. Otolaryngol Head Neck Surg 1997;117:648–52. 21. Esclamado RM, Glenn MG, McCulloch TM et al. Perioperative complications and risk factors in the surgical treatment of obstructive sleep apnea syndrome. Laryngoscope 1989;99:1125–9. 22. Gabrielczyk MR. Acute airway obstruction after uvulopalatopharyngoplasty for obstructive sleep apnea syndrome. Anesthesiology 1988;69:941–3. 23. Riley RW, Powell NB, Guilleminault C. Obstructive sleep apnea syndrome: a review of 306 consecutively treated surgical patients. Otolaryngol Head Neck Surg 1993;108:117–25. 24. Jamieson A, Guilleminault C, Partinen M, Quera-Salva MA. Obstructive sleep apneic patients have craniomandibular abnormalities. Sleep 1986;9:469–77. 25. DeBerry-Borowiecki B, Kukwa A, Blanks R. Cephalometric analysis for diagnosis and treatment of obstructive sleep apnea. Laryngoscope 1988;98:226–34. 26. Riley RW, Powell N, Guilleminault C. Current surgical concepts for treating obstructive sleep apnea syndrome. J Oral Maxillofac Surg 1987;45:149–57.
12 Skeletal facial corrections Walter Hochban
Introduction Owing to the multiple etiologies of sleeprelated breathing disorders (SRBDs) e.g. obstructive sleep apnea (OSA) with numerous different parameters influencing upper airway collapse,1–3 it appears highly unlikely that every patient is a suitable candidate for all treatment options. Unlike medical treatment options, which may be implemented as therapeutic trials generally without significant risk of morbidity and mortality, the potential risks of surgery require a greater degree of certainty of success before proceeding. The skeletal dimensions of the face, particularly the position of the jaws, have a major influence on the shape and patency of the upper airway. Numerous inherited or acquired clinical syndromes with craniofacial changes (Pierre–Robin, Treacher–Collins, Goldenhar, Hallermann–Streiff, Pfeiffer, Apert and Crouzon syndromes) are significantly associated with SRBD. Mandibular deficiency represents the most frequent form of dysgnathia. Even moderate variations of maxillomandibular size, and jaw and head position, may induce SRBD in patients with retrognathia. The occurrence of SRBD is increased if retrognathia is associated with certain craniofacial and morphologic characteristics, e.g. vertical and dolichofacial (‘long face’). This results in a steep mandibular base which promotes a
dorsal and caudal displacement of the chin and the adjacent tongue base and suprahyoid musculature. Mouth opening with rotation of the mandible along the hinge axis accentuates this displacement. Thus, surgical correction of certain craniofacial types is a valuable tool for the treatment of SRBD. The historical development in recent years towards a systematic approach to treat OSA by skeletal facial corrections started about two decades ago with single case reports,4–8 in spite of the fact that surgical corrections of skeletal facial deformities such as dysgnathias were already well established in craniomaxillofacial surgery. During the 1980s the high percentage of failure after UPPP led to the search for more efficient treatment modalities and work on the indications for different surgical options for successful treatment of OSA.9–13
Preoperative diagnostic essentials A careful clinical investigation of the complete upper airway by a trained specialist is essential prior to any kind of treatment, even if only conservative treatment is considered. Clinical examination is important not only with respect to possible surgical intervention, but
194
Skeletal facial corrections
also to exclude underlying pathologic conditions, e.g. tumors, prior to instituting conservative treatment with nasal continuous positive airway pressure ventilation (nCPAP). These are found in less than 5% of the sleep apnea patients.14–19 With respect to surgical procedures, status of the teeth, their position and the maxillomandibular relationship are important to rule out possible skeletal disorders. A large series of case reports supports the importance of clinical evaluation of skeletal disorders, mainly of the mandible, as possible factors in the pathophysiology of OSA.20–25 A multitude of static and dynamic investigation procedures have been used to locate the site of obstruction and predict successful outcome prior to surgical intervention. Rhinomanometry and acoustic rhinometry are only useful to diagnose impairment of nasal breathing.26 CT as well as MRI scanning, as mentioned earlier,27 do not provide reliable information about the dynamic process of the upper airway in OSA. Information about the different pharyngeal sizes, for instance, does not have any therapeutic consequences for the surgical treatment of OSA. The only valuable diagnostic tool for those considering skeletal surgery is cephalometry.28,29 Cephalometrically, in about 40% of OSA patients (predominantly non-obese patients) characteristic craniofacial patterns can be identified.28,29 Under the assumption that SRBD presents a more functional than mechanical problem, functional dynamic evaluation such as pressure, flow, or Pcrit measurements are better tests. Besides routine polysomnographic evaluation, additional dynamic techniques permit an investigation of SRBD qualitatively and also quantitatively and may be useful for preoperative evaluation. Esophagus pressure measurements represent the gold standard method for the assessment of upper airway occlusion during sleep.30,31 For the detection of mixed
apneas (with a long central component) and a moderately increased upper airway resistance, esophageal pressure swings sensitively reflect an increasing respiratory effort, which is essential for the decision to operate or not. Upper airway pressure measurements with a multisensor catheter are able to locate the site of collapse,32–36 but there is great variability, and upper airway obstruction usually involves more than one specific site of obstruction. The same problem occurs with pharyngeal fiberoptic endoscopy;37,38 with or without additional use of the Müller maneuver the selective surgical correction of specific sites of obstruction leads only to a change of the site of obstruction.39 In our experience, both techniques are only valuable for specific minor secondary refinements after major improvement of pharyngeal collapse by skeletal corrections. The measurement of the critical pharyngeal closing pressure (Pcrit) makes it possible to quantify pharyngeal collapse.40–43 Skeletal advancement usually reduces Pcrit by about 8 cmH2O (own measurements), which means that patients who need greater reduction of Pcrit (e.g. due to considerable obesity) are obviously not good candidates for this kind of surgery. In the clinical setting, these kinds of measurements are not routine and, unfortunately, at present there is no clear-cut protocol for evaluation of these patients. However, in the future these measurements may help the clinician predict the success of different therapies for OSA.44
Patient selection and indication for surgical treatment (MMO) In cases where the number of obstructive events exceeds a certain level (e.g. apnea index
Patient selection and indication for surgical treatment (MMO) (AI) > 10, apnea-hypopnea index (AHI) > 20, respiratory disturbance index (RDI) > 20) it seems not to be important whether these events are more or less complete obstructions. Even short respiratory disturbances which do not fulfill the classic criteria of apneas or hypopneas interact with sleep and may provoke a considerable number of arousals. There is no question that simple primary snoring (International Classification on Sleep Disorders, 780.53–1)45 is not an indication for major skeletal corrections, but—beyond a certain threshold (RDI > 20 ?)—it does not matter whether we have an upper airway resistance syndrome (UARS) or mere complete OSA. Pharyngeal properties, e.g. pharyngeal collapsibility, are of much greater importance for the preoperative prediction of postoperative success, which certainly means complete elimination of all obstructive events. A reduc-
Aa
Bb
195
tion of 50% is not relevant—even if this reduction is statistically significant—unless the number of events is reduced below a critical level (AHI < 10/h, RDI < 20/h). As stated earlier, skeletal maxillary and mandibular advancement are able to reduce critical pharyngeal closing pressure, Pcrit, by about 8 cmH2O. Therefore, patients with extremely high Pcrit may not be good candidates for this kind of surgery. Often, these patients with high Pcrit are extremely obese, and considerable obesity is a hint that any craniofacial changes may be of minor importance in the etiology of OSA. During the primary visit at the sleep laboratory, in addition to a careful routine clinical examination, standardized lateral X-rays are taken and cephalometry is performed. This simple procedure may give an indication of whether craniofacial changes (retrognathic, dolichofacial appearance) may influence upper
Cc
Figure 12.1 (A) ‘Normal’ mesofacial type—no primary indication for skeletal corrections. (B) Dolichofacial type with pharyngeal narrowing—primary indication for maxillomandibular advancement osteotomy. (C) Retrognathic type with class II malocclusion—primary indication for maxillomandibular advancement osteotomy with correction of malocclusion.
196
Skeletal facial corrections
Table 12.1 Indications for surgical treatment of OSA by maxillomandibular advancement.
Table 12.2 Contraindications for surgical treatment of OSA by maxillomandibular advancement.
Obstructive SRBD Relevant SRBD (RDI > 20) Cephalometric pharyngeal obstruction (PAS/ML < 10 mm) Retrognathic facial type (angle SNB < 77º) Dolichofacial type (angle ML/NSL > 34º)
Non-obstructive SRBD Obstructive SRBD of extremely long duration (?) Mixed SRBD with long central/only short obstructive parts Wide pharyngeal space (PAS/ML > 15 mm) No skeletal facial changes Considerable obesity (BMI >t32 kg/m2?) Alcohol/drug abuse Old age (due to changing sleep pattern with old age) (?)
SRBD, sleep-related breathing disorder; RDI, respiratory disturbance index; PAS, posterior airway space; ML, mandibular plane; SNB, sella–nasion–B-point of mandible; NSL, nasion–sella line.
SRBD, sleep-related breathing disorder; PAS, posterior airway space; BMI, body mass index.
airway function and patency. Surgical treatment by skeletal advancement is considered if patients fulfill certain cephalometric criteria: (1) retrognathic appearance (angle sella–nasion–B-point of mandible, SNB < 77°, for instance) and/or dolichofacial appearance (steep mandibular plane, e.g. angle ML–NSL > 34°)—in most of these patients, a pharyngeal narrowing (posterior airway space (PAS) < 10 mm) is seen concomitantly (Figure 12.1); (2) patients with less obvious skeletal changes are considered for surgery if they prove to have a highly narrow PAS and are not extremely obese (body mass index (BMI) < 32 kg/m2). In patients with an AHI or an RDI of 20 events per hour of sleep or more, the question arises whether these events are more or less obstructive SRBD (Table 12.1). Non-obstructive SRBD should be excluded from any surgical treatment. Surgery is not the treatment of choice for periodic respiration, since the underlying pathomechanism of this disorder is attributed to deteriorated chemoreceptor function. Most of the patients have mixed SRBD. If these patients have a predominantly central component and only a minimal obstructive component, it is questionable whether they
are candidates for surgery. Another group of patients who may fulfill all criteria for surgery might present with very long apneas. In these cases, where it takes a long time until the apneic events are terminated by an arousal, central changes such as diminished chemoreceptor sensitivity must be assumed. Therefore, surgical success is unlikely (Table 12.2). Craniofacial changes and obesity are not mutually exclusive. In an obese patient, it is difficult to determine whether SRBD is the consequence of obesity or the craniofacial changes. Successful treatment of the obesity may reduce the SRBD to a level where no surgery is necessary. The advisable strategy for obese patients with craniofacial changes should be to first treat the weight problem. Surgical intervention is normally only considered for our patients with a BMI of 32 kg/m2 or less. Another uncertain factor is age, because of changing sleep patterns with age. Our oldest patient was 67 at the time of surgery. At a 5year follow-up, he was asymptomatic with an
Surgical principles and techniques RDI < 10/h. Excessive alcohol use or drug abuse should be an exclusion criterion, as is a wide pharyngeal airway space at all levels without any skeletal changes.
197
A A
Surgical principles and techniques The importance of abnormal skeletal craniofacial configuration as an important causal factor is well known.4–13,21–25,46–53 In addition to standard techniques, recent developments include gradual distraction osteogenesis in the face according to the Ilizarov principle, which in extreme cases may be an alternative to conventional osteotomy especially in growing children.54
B B
Mandibular advancement Over the years, various techniques have been described for mandibular advancement surgery (vertical oblique ramus osteotomy with and without bone graft, C-osteotomy, inverted L-osteotomy, etc.). Our standard approach for mandibular advancement osteotomy is the bilateral retromolar sagittal split osteotomy as originally described by Obwegeser and Dalpont in the 1950s55–57 via an intraoral approach (Figure 12.2a). A lingual horizontal osteotomy of the lingual table of the ascending ramus is performed cranial to the entrance of the inferior alveolar nerve, and then a vertical osteotomy of the outer cortex is performed distal to the molars. Between these two osteotomy lines, the mandibular angle is split sagittally. The neurovascular bundle of the inferior alveolar nerve stays within the central distal part of the
Figure 12.2 (A) Mandibular advancement by bilateral retromolar sagittal split osteotomy via an intraoral approach. (B) Modification according to Hunsuck.
mandible. Whenever possible, particularly if the advancement is to be minor, a modification, as described by Hunsuck,58 where the lingual cortical aspect of the posterior border of the ascending ramus is preserved to the
198
Skeletal facial corrections
Figure 12.3 Maxillary advancement by Le Fort-l osteotomy.
proximal segment, is used (Figure 12.2b). This means that the attachments of the medial pterygoid muscles can be preserved. The proximal segments with the temporomandibular joints stay in place, and the distal toothbearing mandibular segment with the adjacent suprahyoid and genioglossal muscles is advanced. After proper positioning of the segments is achieved, fixation is accomplished by transoral bicortical positioning miniscrews. Originally developed for the correction of bite discrepancies (class II malocclusion), the amount of advancement is determined by the dental occlusion. For the surgical treatment of OSA, a mandibular advancement of at least 7–8 mm is mandatory, and we routinely perform mandibular advancement of 10 mm.
Maxillary advancement Maxillary advancement in patients with OSA can best be accomplished by Le Fort-I
Figure 12.4 Fixation of the mandibular segments is achieved by transoral bicortical mini-screws and fixation of the maxilla with miniplates at the piriform aperture and the zygomaticoalveolar buttresses.
Surgical principles and techniques osteotomy with the down-fracture technique59 (Figure 12.3). Via an intraoral approach, a subperiosteal mobilization exposes the maxillary pillars from the piriform aperture to the pterygopalatine fossa and the nasal floor. The piriform aperture, maxillary sinus walls, zygomaticoalveolar buttresses and nasal septum are osteotomized at the Le Fort-I level, and the tooth-bearing segment of the maxilla and the palatal plate down-fractured. After mobilization and advancement, fixation in the new position is achieved with miniplates at the piriform aperture and the zygomaticoalveolar buttresses (Figure 12.4). During the procedure, after down-fracture of the maxilla, additional nasal septal corrections can be performed very easily if necessary. In cases with normal dental occlusion (class I occlusion) (in our series more than 80% of the patients), maxillary advancement corresponds to
A A
C
B B
D
199
mandibular advancement of 10 mm. In patients with class II malocclusion, maxillary advancement is arranged according to the planned correction of dental malocclusion. Nevertheless, maxillary advancement also considerably influences velopharyngeal muscle patency. Therefore, maxillary advancement should achieve at least 5–6 mm in these special cases.
Genioplasty In most cases (90% of our patients), maxillomandibular advancement is the only surgical intervention needed. In addition to mandibular advancement osteotomy, however, advancement of the genial tubercles with the adjacent genioglossal and geniohyoid muscles may support the effect of protrusion (Figure 12.5). Via an intraoral approach, a horizontal
Figure 12.5 Advancement of the genial tubercle (A,B) may support the effect of protrusion (C,D).
200
Skeletal facial corrections
sliding osteotomy of the chin is performed and the distal segment is advanced and fixed in the new position with wires or miniplates. In contrast to conventional esthetic genioplasty, the muscles must stay in place at the posterior mental spine. If cosmetic changes are not desired, a subapical window osteotomy of the mentum may be chosen with advancement of the posterior cortical table with the genial tubercle and the adjacent muscles only; the anterior cortical table and the cancellous bone is cut off to avoid chin augmentation, and the remaining cortical part is rotated and fixed with screws for proper tension of the muscles. Both procedures can be easily combined with maxillary and mandibular advancement if desired. In our series, genioplasty was only performed as a second-stage procedure in less than 10% of the patients, due to lack of success after primary maxillomandibular advancement. During surgery, muscles, ligaments and tendons attached to the jaw must be equally advanced and straightened. This results in a modification of pharyngeal and palatal muscles as well as lingual, genioglossal and suprahyoid muscles. Thus, the effectiveness of maxillomandibular advancement is most probably caused by tension of suprahyoid and velopharyngeal muscles, even if the additional place for the tongue and the enlarged posterior airway might have some importance.
Surgical treatment concepts Step-by-step surgery tends to look for isolated sites of obstruction which are surgically corrected in a first step. This means that patients with an isolated obstruction of the
velopharynx at the level of the soft palate receive a uvulopalatopharyngoplasty (UPPP),60 while patients with an obstruction at the base of the tongue undergo an anterior repositioning of the genioglossus muscle and the hyoid bone by chin advancement osteotomy and hyoid myotomy and suspension (GAHM). Patients with obstructions at both the velo- and hypopharynx undergo both procedures. With this ‘phase I surgery’ Riley et al60 reported a success rate (reduction of AHI by > 50%/AHI < 20 events/h) of more than 60% in 249 patients. The non-responders tended to be more obese and have more severe mandibular deficiency than the responders, and the likelihood of a response tended to be diminished with increasing preoperative AHI. Nevertheless, the reproducibility of such results remains to be confirmed. Other study groups worldwide have not been able to confirm these good results using phase I surgery, with a short-term follow-up success rate of less than 40%.61–64 After unsuccessful phase I surgery Riley et al60 recommend as a second step maxillomandibular advancement osteotomy, their success rate being 97%. Our concept is different.65,66 A success rate of 40–60% after phase I surgery for OSA means that every second patient had no benefit from this kind of surgery. In Europe, patients will not accept a surgical procedure with a 50% chance for success, if they have excellent conservative treatment alternatives. Furthermore, additional maxillary advancement as a second-stage procedure after UPPP may enhance possible side-effects and complications of UPPP, such as velopharyngeal insufficiency and nasal regurgitation. Whereas maxillomandibular osteotomy paradoxically leads to less complaints of pain than phase I surgery or UPPP, pain and unsuccessful results after first-step procedures adversely affect patients’ confidence and compliance.
Results In our experience, the advancement of the maxillomandibular complex should be at least 7–8 mm in the sagittal direction to be reliably effective. To be on the safe side, a sagittal advancement of the mandible of at least 10 mm should be attempted. In cases with extreme mandibular deficiency with class II bite discrepancy (more than 10 mm), mandibular advancement only may suffice for bite correction as well as for correction of OSA. In patients with predominantly dolichofacial appearance, counter-clockwise rotation of the maxillomandibular complex may support efficacy, due to further advancement of the genial tubercle with the adjacent suprahyoid muscles (the pogonion is advanced and rotated in a frontocranial direction). More advancement does not necessarily mean more efficacy. The main influence of skeletal advancement is less the mechanical enlargement of the maxillofacial complex (viscerocranium) than the functional influence on the upper airway muscles, which are stretched and straightened by advancement of their origins. In our opinion, velopharyngeal soft tissue resection should be reserved for secondary refinements in patients with OSA or for patients with primary snoring only.
Results Abolition of all obstructive events may be an ambitious goal and can not be guaranteed in every case. However, success must be defined as adequate reduction of the number of apneas, hypopneas and arousals down to a physiologic level comparable to the results with nCPAP therapy. Reduction of 50% of the events may not be enough, even if this reduction is significant. In our opinion postopera-
201
60 AI AHI RDI
50 40 30 20 10 0
Pre-op
n = 54 CPAP
Post-op
1-yr Post-op
Figure 12.6 Results of maxillomandibular advancement in 63 consecutive patients with a 1-year follow-up compared to CPAP: RDI/AHI/AI (events/h).
tive AHI should be reduced to below 10 events/h or RDI below 20 events/h. Furthermore a physiologic profile of sleep stages should be re-established. Even more important are the subjective symptoms of the patients, such as daytime sleepiness etc.67,68 In properly selected patients with moderate or severe OSA, surgical maxillomandibular advancement yields a success rate of 90% without any further secondary corrections.65,66 Comparable results are also reported from other centers.13,60,61 In about 10% of our patients, additional surgical procedures (adenotonsillectomy, UPPP, genioplasty) were necessary. Our case series of 63 consecutive patients (4 women and 59 men), all with a preoperative AHI > 20/h, demonstrates the strategy and the results obtained (Figures 12.6–12.8). Preoperative median BMI was 27 kg/m2, with a range from 22 to 36 kg/m2. Preoperative mean SNB angle was 75°
202
Skeletal facial corrections
80
ST3/4
70 60
ST1/2
REM
50 40 30 20 10 0
Pre-op
n = 54 CPAP
Post-op
1-yr Post-op
Figure 12.7 Results of maxillomandibular advancement in 63 consecutive patients with a 1-year follow-up compared to CPAP: sleep stages 1/2, 3/4, and REM (%).
90 80 70 60 50 40 30 20 10 0
O2
