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Diagnostic approach to obstructive sleep apnea in children
Sleep Medicine
Reviews,
Vol. 2, No. 4, pp 255-269,
1998
SLEEP MEDICINE
REVIEW ARTICLE
Diagnostic in children
approach
to obstructive
sleep apnea
Valerie Kirk’, Andre Kahn’, Robert T. Brouillette3 ‘Respiratory Division, Alberta Children’s Hospital, Calgary, 2University Libre de Bruxelles, Hdpital Universitaire des Enfants, Brussels, Belgium and 3Department of Pediatrics, McGill University/Montreal Children’s Hospital, Canada Obstructive sleep apnea syndrome (OSAS) in childhood is a disorder of breathing during sleepcharacterized by prolonged partial upper airway obstruction and/or intermittent complete obstruction that disrupts normal ventilation during sleep and normal sleep patterns. A spectrum of severity related to the degree of upper airway resistance, to the duration of the disease, to the presence or absence of kypoxemia episodes, and to certain clinical features can be described. Symptomatic children may not fit the criteria for diagnosis established for OSAS in adults; age-specific standards are needed. Both anatomical factors that increase upper airway resistance, e.g. adenotonsillar kypertropky, and functional processes that decrease upper airway tone, e.g. REM sleep, contribute to the patkogenesis of pediatric OSAS. Sequelae of OSAS in children include neurobekavioural abnormalities, stunting of growth, and car pulmonale. Both the history and physical examination should target the sleeping child; parents often report loud snoring, difficulty breathing, and obstructive apneas. The gold standard investigation to establish the diagnosis and to quantitate disease severity is overnight polysomnograpky. Home cardiopulmonary sleep studies have been shown to be an accurate and practical alternative to overnight laboratory polysomnograpky for routine evaluation of non-complex children with adenotonsillar kyperfropky. Children with documented severe OSAS are at increased post-operative risk for airway compromise and should be observed and monitored carefully. Adenotonsillectomy is the most common therapy for OSAS in children; as a secondline treatment, the use of nasal CPAP in children with OSAS has been very successful in experienced hands. Key words: child, sleep apnea syndromes, positive airway pressure, polysomnography
sleep state, breathing,
tonsils,
adenoids,
continuous
stupid-lazy child who frequently suffers from headaches at school, breathes through his mouth instead of his nose, snores and is restless at night, and wakes up with a dry mouth in the morning, is well worthy of the solicitous attention of the school medical officer.“
“The
Correspondence to be addressed to: Robert T. Brouillette, MD, 2300 Tupper Street, C-920, Montreal, Quebec, Canada, H3H lP3. (Fax: 514-934-4356; email: [email protected]) 1087-0792/98/040255
+ 15 $12.00/O
0 1998 W.B. Saunders
Company
Ltd
256 Table 1
V. Kirk
The severity spectrum for pediatric
Reproduced from Broillette RT, Waters how safe? how effective? Am J Respir
et al.
sleep-related
upper airway obstruction
K. Oxygen therapy for pediatric obstructive Crit Care Med 1996; 153: 1-2, with permission.
sleep
apnea
syndrome:
This nineteenth-century reference was published in an article entitled “On some causes of backwardness and stupidity in children” [l] and describes the unfortunate sequelae resulting from lack of recognition and treatment for the common disease we now know as the pediatric obstructive sleep apnea syndrome (OSAS). OSAS was initially described in the medical literature in 1966 as a breathing disorder during sleep affecting an obese adult male [2]. At this time, the pediatric medical community had not yet recognized the diagnosis of OSAS; however, several pediatric cases of hypertrophied tonsils and adenoids causing congestive heart failure and car pulmonale were reported [3,4]. It was not until 1976 that the first case reports of obstructive sleep apnea in children were published [5]. Since then, OSAS in children has been the focus of much attention and research and is now widely accepted as a significant cause of morbidity in childhood. North American epidemiological data on OSAS in childhood are not currently available; however, the prevalence in England of OSAS amongst children aged 4-5 years is estimated at 0.7% [6]. The peak incidence is in the 2-5-year-old age group. There is no male preponderance, as seen in adult OSAS [7,8]. Untreated, OSAS contributes to a variety of important medical and developmental problems including failure to thrive, cardiopulmonary disease, and developmental delay. This review describes the presentations and associations of OSAS in children. Key elements of the history and physical exam that will alert the clinician to a possible diagnosis of OSAS are reviewed. Discrimination between benign snoring in childhood and those children requiring further investigation is discussed. A review of diagnostic investigations and a brief summary of current treatment modalities is also included.
Definition OSAS in childhood, as defined by the American Thoracic Society, is a disorder of breathing during sleep characterized by prolonged partial upper airway obstruction and/or intermittent complete obstruction, obstructive apnea, that disrupts normal ventilation during sleep and normal sleep patterns [9]. A spectrum of severity related to the degree of upper airway resistance, the duration of the disease, the presence or absence of hypoxemia episodes and to certain clinical features has been suggested by
Sleep apnea in children
Reproduced diagnostic permission.
from Brouillette RT, Hanson D, David R, Klemka L, Szatkowski approach to suspected obstructive sleep apnea in children. ]
257
A, Fembach
S, Hunt
Pediatr 1984; 105: 10-14,
C. A with
Brouillette and Waters [lo] (Table 1). At one end of the spectrum (Grade 0) is snoring with no associated abnormalities or morbidities. Snoring has been estimated to occur in 7-12% of children [11,12]. At the opposite end of the spectrum are those children with severe disease and evidence of end-organ damage due to severe and prolonged hypoxemia and airway obstruction (Grade 5). Most children present to medical attention at intermediate stages with definite obstructive apnea, with or without associated hypoxemia (grades 4 or 3, respectively). Many children with OSAS have either continuous or prolonged partial airway obstruction associated with clinical manifestations consistent with OSAS; often they do not fit the criteria for diagnosis established for OSAS in adults. For this reason, adult criteria for diagnosis, e.g. an apnea index >5/h, are not applicable to the pediatric population [13]. Diagnosis is based on clinical features and quantitative assessment of respiratory and gas exchange patterns during sleep.
Presentation The wide range of signs and symptoms associated with OSAS in children is a consequence of the variability in developmental stages, the variable severity, and the diversity of underlying etiologies. The most common etiology of OSAS in otherwise normal children is adenotonsillar hypertrophy. Comparison of 23 children with confirmed OSAS due to adenotonsillar hypertrophy with 46 age- and sex-matched healthy controls showed increased frequencies of several symptoms (Table 2) [14]. The three most predictive symptoms associated with OSAS are loud snoring, difficulty breathing during sleep, and sleep-related pauses in breathing witnessed by the parents [14]. Children may also experience frequent arousals during sleep due to OSAS, although
V. Kirk
258
RUs
et al.
1;
1
pus
RDS
pDS
Upstream segment
Collapsible
segment
Figure 1 Starling resistor model of upper airway. Upper airway is represented as tube with collapsible segment. Segments upstream (nasal) and downstream (tracheal) from collapsible segment have fixed diameters and resistances (Rus and R,) and pressures (Pus and I’&, respectively. Collapse occurs when the pressure surrounding the airway (P,,,t) becomes greater than pressure within the airway. (Reproduced from Marcus CL, McColley SA, Carroll JL, Loughlin GM, Smith PL, Schwartz AR. Upper airway collapsibility in children with obstructive sleep apnea syndrome. I Appl Physiol 1994; 77: 918, with permission.)
more recent data suggests that sleep architecture is relatively well preserved in children with OSA as compared to adults [15]. Enuresis has been reported to occur more frequently in children with OSAS but is a useful clinical sign only if the child previously has been dry at night [3,14,16,17]. Daytime symptoms that may be associated with OSAS include disorientation on waking, morning headaches, and mood and personality changes. An “adenoidal facies” and/or pectus excavatum may be present on examination of the awake child 118,191.
Pathogenesis Two hypotheses have been suggested to explain the pathogenesis of OSAS in children and adults. The StarZing resistor principle has been proposed to explain the frequent occurrence of partial upper airway obstruction associated with flow limitation (Fig. 1) [20,21]. During inspiratory flow limitation, airflow is determined by pressuregenerating changes resistance upstream (for instance at the adenoid-palate level) from the collapsible segment (pharynx); airflow is not augmented by increased negative pressure downstream (esophageal pressure), even when inspiratory pressure-generating muscles contract forcefully. Airflow limitation can be recognized on polysomnography by a,flattening of the nasal airflow tracing during mid-inspiration (Fig.
1) POI. During activation
inspiration a negative pressure is generated within the pharynx due to of the diaphragm and intercostal muscles [22]. Collapse of the upper airway
Sleep apnea in children
open
Neck
-4 flexion
Neck
259
extension
Figure 2 A model of pharyngeal airway maintenance illustrating the opposite forces that affect airway diameter. Airway constricting (suction force) and airway dilating forces (pharyngeal muscles) are shown on either side of a fulcrum. The balance of forces is dynamic. A decrease in pharyngeal dilating muscular force during REM steep can contribute to airway closure. (Adapted from Thach BT. Potential role of airway obstruction in SIDS. In Krous H, Culbertson H (eds). Sudden Infint Death Syndrome. Baltimore, MD: Johns Hopkins Press 1988, with permission.)
Table 3
Anatomical
factors predisposing
to OSAS in children
due to the force of this negative pressure is prevented by simultaneous activation of oropharyngeal dilator muscles such as the genioglossus muscle that protrudes the tongue [22,23]. According to the balance offerces hypothesis, OSAS occurs whenever an imbalance in these forces favors negative oropharyngeal pressures during inspiration [22,23] (Fig. 2). Anatomic factors that increase resistance to airflow therefore predispose to OSAS. The most common anatomical factor in children is adenotonsillar hypertrophy
260
Table 4 Functional
V. Kirk et al. causes of OSAS in children
but there are numerous nasal, pharyngeal and craniofacial abnormalities that occur less frequently (Table 3). Functional abnormalities also contribute to OSAS in children. The structure of the upper airway may be normal on physical examination, but if coordinated activation of both inspiratory and oropharyngeal dilator muscles does not occur during inspiration, OSAS will occur. The most common functional process contributing to OSAS is rapid eye movement (REM) sleep. During this stage of sleep, phasic muscle activity of the oropharyngeal muscles may be significantly depressed. Diaphragmatic activation continues to generate negative oropharyngeal pressures but tone in the upper airway tissues is reduced, leading to increased upper airway resistance and partial or complete airway obstruction during inspiration. In a recent series of pediatric evaluations for OSAS, the median apnea/hypopnea index was 6.5 versus 0.8 events/h in REM and non-REM sleep, respectively [24]. Other functional factors contributing to pediatric OSAS include abnormalities of neural function and drugs which depress the central nervous system (Table 4) 1251. Obstructive apnea associated with prematurity is reviewed elsewhere [26]. Many children with OSAS have a complex interaction of both anatomical and functional abnormalities.
Sequelae It is important to identify the presence of OSAS and to determine accurately the etiological factors to ameliorate the significant morbidity’that can result from inadequate
Sleep apnea in children
261
Table 5 Sequelae of OSAS in children
treatment (Table 5). Cor pulmonale, pulmonary hypertension, and congestive heart failure characterize the most severe and prolonged cases of pediatric OSAS. Similarly, repetitive, severe asphyxial episodes and sleep disturbance clearly interfere with the normal development and functioning of the child. Secondary enuresis is frequent in children with OSAS and has been shown to resolve with treatment of the OSAS [27]. However, much more work needs to be done on the early identification of neurobehavioral sequelae of pediatric OSAS. Poor growth velocity associated with adequate caloric intake and absence of chronic illness (failure to thrive) is a frequent consequence of OSAS in children. The underlying mechanism is not well established but current hypotheses include the presence of a hypermetabolic state during sleep. In a recent article by Marcus et al. energy expenditure during sleep was shown to decrease significantly following adenotonsillectomy for OSAS. There was an increased post-operative weight gain without a significant change in caloric intake [28]. Alternatively, it has been suggested that nocturnal hypoxemia affects the neurohormonal balance of hypothalamic hormones required for adequate growth. Growth hormone secretion normally occurs during sleep and may be decreased due to frequent arousals. Nasal obstruction, due to chronic rhinitis or adenotonsillar hypertrophy, alters the senses of taste and smell and thus may diminish appetite. It is also more difficult for chronic mouth breathers to eat and breathe at the same time and some children with very large tonsils have difficulty swallowing. A complex interaction of factors in OSAS is most likely responsible for failure to grow adequately. Importantly, growth usually accelerates after adenotonsillectomy in children with OSAS (Fig. 3). Although there is increasing epidemiological evidence implicating OSAS as a risk factor for systemic hypertension in adults, the literature in children is scant and conflicting. Guilleminault et al. reported the presence of diurnal systemic hypertension in 10% of 50 children with OSA, all of whom were older than 10 years [29]. More recently, however, Kunzman et aI. were unable to show any abnormalities in diastolic or systolic arterial pressures in their group of 22 children [30].
262
V. Kirk
et al.
5
1
2 Age
3 (years)
4
5
6
Figure 3 Shown are the weight curves of six patients with failure to thrive caused by OSA. In two patients, adequate data were available to reconstruct pre-operative curves (---). Note the rapid weight gain (“catch-up growth”) after surgical relief of airway obstruction (-). Fifth and ninety-fifth percentiles for normal children are shown. (Reproduced from Brouillette RT, Fernbach SK, Hunt CE. Obstructive sleep apnea in infants and children. J Pedintr 1982; 100: 31, with permission.)
Diagnostic
approach
Making the diagnosis of OSAS in children begins with a thorough history. Special attention must be paid to details of sleep, a period of time generally ignored in a routine medical interview. Ask specifically about snoring, difficulty breathing or periods of no apparent breathing. Inquire about usual sleep position as some children with OSAS adopt peculiar postures during sleep to maximize airway patency. Pay particular attention to children with obvious craniofacial abnormalities or Down’s syndrome to determine when these high-risk patients require further investigations. Presence of enuresis, especially if recent in onset, and changes in appetite or eating habits should be recorded. Additionally, changes in behaviour or school performance, including relevant teacher reports, should be sought. A thorough ear, nose and throat exam, including a search for a deviated nasal septum, nasal polyps or rhinitis, should be performed. Tonsillar size and general oropharyngeal anatomy should be examined for signs of abnormality such as a bifid uvula, suggestive of an underlying cleft palate.The cardiovascular exam is such as digital clubbing, a right directed towards evidence of car pulmonale, ventricular heave, a displaced point of maximal impulse, loud second heart sound, or a murmur suggestive of tricuspid regurgitation. Pulmonary exam should include observation for increased work of breathing while awake, presence or absence of cyanosis, and description of breathing rate and pattern.
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263
The most frequent abnormalities on physical exam are tonsillar enlargement and inability to breathe through the nose, representing adenoidal nasal obstruction. However, the exam performed with the child awake is often completely normal. Ideally, the examiner should observe any child suspected of having OSAS while the child is asleep. At times the child with severe OSAS will fall asleep in the office facilitating examination in the most symptomatic state. Alternatively, asking the parents to obtain an audio or audio-visual tape of the child sleeping may prove to be an efficient means of observing the child asleep. Whether such recordings are representative or worst case data should be ascertained. The differential diagnosis of sleep disruption in children includes other medical and developmental disorders that should be considered. Gastroesophageal reflux, asthma, and seizure disorders can usually be ruled out by careful history and physical examination of the child. Developmental problems, such as parasomnias (night terrors, confusional arousals, sleep-walking) can also cause sleep disruption and are generally easily distinguished from OSAS. These disorders can also co-exist in patients with OSAS, making the diagnosis more challenging. For children with a history and/or physical examination suggestive of obstructive sleep apnea, the gold standard investigation for confirmation of both diagnosis and disease severity is overnight polysomnography (PSG). Studying children in this manner presents unique challenges. Skilled and experienced technicians are essential in order to win the cooperation and trust of young children. The laboratory setting must be soothing, and non-threatening. A typical hospital sleep laboratory setting may frighten a child, thus preventing the technicians from obtaining even the most elementary set-up. Removing all non-essential hospital equipment from the immediate area, the display of colorful and interesting posters, diversion with favorite video shows and a relaxed, non-threatening approach to lead application all help to gain the cooperation of the child. Parents should be encouraged to bring favorite toys or items from home that may help to create normal bed-time routines in the sleep laboratory. We strongly recommend that a parent be required to stay with the child overnight, as the child may waken and require parental attention in order to re-establish sleep. The American Thoracic Society recently established standards and criteria for cardiopulmonary sleep studies in children. These include measurements of respiratory movements, airflow, ventilation and oxygenation, sleep staging, electrocardiogram, electromyogram and audiovisual recording. Supervision by a trained technician is required throughout the study with additional record keeping of unusual events or behaviours during the night [9]. Additional information regarding sleep positioning, snoring, and arousal frequency is easily obtained by adding videotaping during PSG. Normal values for polysomnography in children and adolescents were reported by Marcus et al. (Table 6) [31]. Unfortunately, few scientific data examining the correlation between PSG abnormalities, clinical symptoms, and sequelae of OSAS in children are currently available. The American Thoracic Society recommended further investigation of abbreviated testing, such as unattended home monitoring of oxygen saturation and respiratory pattern. In Montreal, home cardiopulmonary sleep studies were shown to be an accurate and practical alternative to overnight laboratory polysomnography for routine evaluation of non-complex children with adenotonsillar hypertrophy [32]. Adjunctive diagnostic investigations include airway imaging studies such as radiography, or rarely fluoroscopy, of the lateral neck and computed tomography
264
Table 6 Normal
V. Kirk
polysomnographic
et al.
values for children
and adolescents
*Increase in CO, during sleep; tTST= total sleep time. Reproduced from Marcus CL, Omlin KJ, Basinki DJ, Bailey SL, Rachal AB, Van Pechmann WA, Keens TG, Davidson-Ward SL. Normal polysomnographic values for children and adolescents. Am Rev Respir Dis 1992; 146: 12351239, with permission. For additional normal values in children, see also chapter 9 in [43].
of the upper airway for assessment of the choanae and anterior nares. Standard lateral neck radiographs done with the patient awake will identify enlarged adenoids and/or tonsils and occasionally other structural causes of upper airway obstruction. Fernbach et al. noted that 18 of 26 patients with OSAS were correctly identified as having adenotonsillar enlargement on plain radiograph. Subsequent upper airway fluoroscopy, performed with the patients asleep, identified the site of obstruction in 100% of these patients [33]. The relative ease with which a plain radiograph can be obtained makes it a useful adjunct to identify contributing airway abnormalities in OSAS. Fluoroscopy should be reserved for those patients in which the site of airway obstruction is not evident on plain radiograph. In selected patients with evidence of upper airway obstruction, rhinoscopy may be useful in identifying the site [34]. Investigation of children with severe OSAS should also include diagnostic studies for evidence of right ventricular hypertrophy (RVH), pulmonary hypertension, and car pulmonale. This generally involves chest radiograph for assessment of cardiac size, electrocardiogram and frequently echocardiography. Tal et al. reported that the most sensitive diagnostic test for RVH and pulmonary hypertension due to car pulmonale is ventricular scan [35]. They assessed 27 children with OSAS using radionuclide ventriculography and compared the results to those obtained with conventional methods, electrocardiogram and chest radiograph. Cardiac involvement was correctly identified by conventional investigations in only two of 10 patients with abnormal scans. Most importantly, all patients showed improvement on cardiac scans following adenotonsillectomy [35]. Results of echocardiography are variable between centers and operators. Therefore, it is prudent to involve the cardiologists available to you in the decision-making process regarding optimum cardiac investigations. It is also important to consider the diagnosis of OSAS in children who present with unexplained congestive heart failure, pulmonary hypertension or car pulmonale. An early morning blood gas may demonstrate an elevated bicarbonate suggesting a compensated respiratory acidosis; however, a normal morning blood gas does not exclude the presence of nocturnal hypoventilation or hypoxemia. Patients with OSAS who also have prolonged central apnea should undergo imaging studies of the brainstem, most accurately performed by magnetic resonance imaging. Particular attention should be directed to the brainstem and cervico-medullary junction for evidence of a Chiari malformation or space-occupying lesion.
Sleep apnea in children
265
Practice Points
Treatment Adenotonsillectomy is the most common therapy for OSAS in children; however, the treatment for a particular child depends on the underlying abnormalities, the site of obstruction, and the presence or absence of contributing neurological or functional abnormalities. Table 7 reviews possible approaches to treatment. Pharmacological therapy with oral steroids is useful for management of acute airway obstruction due to tonsillar enlargement from infectious mononucleosis; however, administration of moderate doses to patients with OSAS due to adenotonsillar hypertrophy for 5 days was not effective [36]. The search for a medical alternative to adenotonsillectomy should continue as the surgical procedure can be associated with complications, particularly post-tonsillectomy bleeding. The use of nasal CPAP in children with OSAS has been very successful in experienced hands [37,39]. The major indication in children is persistence of OSAS following adenotonsillectomy. Nasal CPAP has also been used for peri-operative stabilization of some patients as airway obstruction may persist immediately postoperatively due to soft-tissue swelling and effects of sedatives and anesthestics [37]. Children with documented severe OSAS are at increased post-operative risk for airway compromise. Rosen et ~2. reported a complication rate of 27% in 37 children undergoing adenotonsillectomy for OSAS. Those children having post-operative complications were more likely to have additional underlying medical conditions such as
266 Table 7
V. Kirk et al. Treatment
of obstructive
sleep apnea in children
craniofacial anomalies, hypotonia, obesity, previous airway trauma, car pulmonale or failure to thrive [40]. The authors recommended overnight observation with an apnea monitor and oximeter for those patients with the additional abnormalities listed above, those under 2 years of age, and those with polysomnographic findings of severe OSAS (Grade 4 or 5). Some patients with no previous evidence of cardiac failure may develop acute pulmonary edema following relief of airway obstruction. Therefore, judicious use of intravenous fluids and frequent post-operative observation are essential.
Research
issues
OSAS in children is a relatively new diagnostic entity and several issues regarding diagnosis, treatment, and sequelae are not yet well studied. The role for abbreviated testing in the home or hospital setting is not well established. The timing of initial testing for children known to be at high risk of OSAS has not been identified. Behaviour and learning difficulties associated with OSAS and the effects of early diagnosis and treatment on these specific problems have not yet been well studied. It remains poorly understood why some children have benign snoring not associated with OSAS and what effects this may have on development and sleep. Upper airway resistance syndrome (UARS) has been identified in adults as a significant cause of morbidity with signs and symptoms of OSAS associated with normal polysomnographic findings. The presence and significance of UARS in children is not yet well defined and requires further study [41,42]. Although a short course of systemic steroids does not appear to have a significant effect on OSAS in children, a recent report of inhaled nasal corticosteroid use in children with adenotonsillar hypertrophy is promising and should be confirmed with further study [34]. As the bacteriology of adenotonsillar hypertrophy becomes better understood, new antibiotics may deserve a clinical trial. Some clinicians are now advocating the use of nasal CPAP for pre- and post-operative stabilization and treatment
Sleep apnea in children
267
of children with OSAS undergoing adenotonsillectomy or UPPl? Optimal peri-operative management of these children is a particularly pressing issue. In many institutions across North America, children undergoing adenotonsillectomy are discharged home within hours of the procedure. Identification of those children at risk of postoperative complications is imperative in order to avoid unnecessary tragedies.
Conclusion OSAS is a significant and treatable cause of morbidity in children. Timely diagnosis is dependent on maintaining an index of suspicion for high-risk children and on establishing a set of routine screening questions regarding sleep habits that can be easily incorporated into routine pediatric and family medicine practice. Further study is required regarding the significance of UARS in children, non-surgical treatment modalities for OSAS, and effects of OSAS on behaviour and learning. High-risk children undergoing surgical correction for OSAS require close post-operative monitoring and may also benefit from peri-operative use of nasal CPAP. Practice Points
V. Kirk et al.
268
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153(2): 866-878. 10 Brouillette RT, Waters K. Oxygen therapy for pediatric obstructive sleep apnea syndrome: how safe? how effective? Am 1 Respir Crit Care Med 1996; 153: 1-2. 11 Ali NJ, Pitson DJ, Stradling JR. Snoring, sleep disturbance, and behaviour in 4-5 year olds. Arch Dis Child 1993; 68: 360-366. 12 Gislason T, Benediktsdottir B. Snoring, apneic episodes and nocturnal hypoxemia among children 6 months to 6 years old: an epidemiologic study of lower limit of prevalence. Chest 1995; 107: 963-966. 13 Rosen CL, D’Andrea L, Haddad GG. Adult criteria for obstructive sleep apnea do not identify children with serious obstruction. Am Rev Respir Dis 1992; 146: 1231-1234. 14 Brouillette RT, Hanson D, David R, Klemka L, Szatkowski A, Fernbach S, Hunt C. A diagnostic approach to suspected obstructive sleep apnea in children. ] Pediatr 1984; 105: 10-14. 15 McNamara F, Issa FG, Sullivan CE. Arousal pattern following central and obstructive breathing abnormalities in infants and children. I Appl Pkysiol 1996; 81(6): 2651-2657. 16 Frank Y, Kravath RE, Pollak Cl’, Weitzman ED. Obstructive sleep apnea and its therapy: clinical and polysomnographic manifestations. Pediatrics 1983; 71: 737-742. 17 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: 741-744. 18 Loughlin G. Obstructive sleep apnea in children. Adv Pediatr 1992; 39: 307-336. 19 Dyson M, Beckerman RC, Brouillette RT. Obstructive sleep apnea syndrome. In: Respiratory Control Disorders in Infants and Children. Baltimore, MD: Williams and Wilkins 1992; 212-230. 20 Marcus CL, McColley SA, Carroll JL, Loughlin GM, Smith PL, Schwartz AR. Upper airway collapsibility in children with obstructive sleep apnea syndrome. J Appl Pkysiol 1994; 772: 918-924. 21 Smith PL, Wise RA, Gold AR, Schwartz AR, Permutt S. Upper airway pressure-flow relationships in obstructive sleep apnea. J Appl Pkysiol 1988; 64: 789-795. 22 Remmers JE, deGroot WJ, Sauerland EK, Anch AM. Pathogenesis of upper airway occlusion during sleep. J Appl Pkysiol 1978; 44: 931-938. 23 Thach BT. Neuromuscular control of upper airway patency. Clinics in Perinatology 1992; 194: 773-788. 24 Morielli A, Ladan S, Ducharme FM, Brouillette RT. Can sleep and wakefulness be distinguished in children by cardiorespiratory and videotape recording? Chest 1996; 109: 680-687. 25 Hershenson M, Brouillette RT, Olsen E, Hunt CE. The effect of chloral hydrate on genioglossus and diaphragmatic activity. Pediatr Res 1984; 186: 516-519. 26 Miller MJ, Martin RJ. Apnea of prematurity. Clin Perinatol 1992 194: 789-808. 27 Marcus CL, Carroll JL, Koemer CB, Hamer A, Lutz J, Loughlin GM. Determinants of growth in children with the obstructive sleep apnea syndrome. J Peds 1994; 1254: 556-562. 28 Guilleminault C, Winkle R, Korobkin R et al. Children of sleep related respiratory resistive load and daytime functioning Eur J Pediatr 1982; 139: 165.
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29 Weider DJ, Sateia MJ, West RF’. Nocturnal enuresis in children with upper airway obstruction. Otolayngol Head Neck Surg 1991; 105: 427432. 30 Kunzman LA, Keens TG, Davidson-Ward SL. Incidence of systemic hypertension in children with obstructive sleep apnea syndrome (abstr.) Am Rev Respir Dis 1991; 141: A808. 31 Marcus CL, Omlin KJ, Basinki DJ, Bailey SL, Rachal AB, Von Pechmann WA, Keens TG, Davidson-Ward SL. Normal polysomnographic values for children and adolescents. Am Rev Respir Dis. 1992; 146: 1235-1239. 32 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: 241-252. 33 Fernbach SK, Brouillette RT, Riggs TW, Hunt CE. Radiologic evaluation of adenoids and tonsils in children with obstructive sleep apnea: plain films and fluoroscopy. Pediatr Radio1 1983; 13: 258-265. 34 Demain JG, Goetz DW. Pediatric adenoidal hypertrophy and nasal airway obstruction: reduction with aqueous nasal beclomethasone. Pediatrics 1995; 953: 355-364. 35 Tal A, Leiberman A, Margulis G, Sofer S. Ventricular dysfunction in children with obstructive sleep apnea: radionuclide assessment. Pediatr Pulmonol 1988; 4: 139-143. 36 Al-Ghamdi SA, Manoukian JJ, Morielli A et al. Do systemic corticosteroids effectively treat obstructive sleep apnea secondary to adenotonsillar hypertrophy? La yngoscope 1997; 197: 1382-1387. 37 Waters KA, Everett F, Bruderer F, MacNamara F, Sullivan CE. The use of nasal CPAP in children. Pediatr Pulmonol 1995; Sll: 91-93. 38 Waters KA, Everett FM, Bruderer JW, Sullivan CE. Obstructive sleep apnea: the use of nasal CPAP in 80 children. Am 1 Respir Crit Care Med 1995; 152: 780-785. 39 Marcus CL, Davidson-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. 40 Rosen GM, Muckle RI’, Mahowald MW, Goding GS, Ullevig C. Postoperative respiratory compromise in children with obstructive sleep apnea syndrome: Can it be anticipated? Pediatrics 1994; 935: 784-788. 41 Guilleminault C, Stoohs R. Chronic snoring and obstructive sleep apnea syndrome in children. Lung 1990; Suppl. 912-919. 42 Guilleminault C, Philip I? Polygraphic investigation of respiration during sleep in infants and children. J Clin Neuropkysiol 1992; 91: 48-55.
Reviews,
Vol. 2, No. 4, pp 255-269,
1998
SLEEP MEDICINE
REVIEW ARTICLE
Diagnostic in children
approach
to obstructive
sleep apnea
Valerie Kirk’, Andre Kahn’, Robert T. Brouillette3 ‘Respiratory Division, Alberta Children’s Hospital, Calgary, 2University Libre de Bruxelles, Hdpital Universitaire des Enfants, Brussels, Belgium and 3Department of Pediatrics, McGill University/Montreal Children’s Hospital, Canada Obstructive sleep apnea syndrome (OSAS) in childhood is a disorder of breathing during sleepcharacterized by prolonged partial upper airway obstruction and/or intermittent complete obstruction that disrupts normal ventilation during sleep and normal sleep patterns. A spectrum of severity related to the degree of upper airway resistance, to the duration of the disease, to the presence or absence of kypoxemia episodes, and to certain clinical features can be described. Symptomatic children may not fit the criteria for diagnosis established for OSAS in adults; age-specific standards are needed. Both anatomical factors that increase upper airway resistance, e.g. adenotonsillar kypertropky, and functional processes that decrease upper airway tone, e.g. REM sleep, contribute to the patkogenesis of pediatric OSAS. Sequelae of OSAS in children include neurobekavioural abnormalities, stunting of growth, and car pulmonale. Both the history and physical examination should target the sleeping child; parents often report loud snoring, difficulty breathing, and obstructive apneas. The gold standard investigation to establish the diagnosis and to quantitate disease severity is overnight polysomnograpky. Home cardiopulmonary sleep studies have been shown to be an accurate and practical alternative to overnight laboratory polysomnograpky for routine evaluation of non-complex children with adenotonsillar kyperfropky. Children with documented severe OSAS are at increased post-operative risk for airway compromise and should be observed and monitored carefully. Adenotonsillectomy is the most common therapy for OSAS in children; as a secondline treatment, the use of nasal CPAP in children with OSAS has been very successful in experienced hands. Key words: child, sleep apnea syndromes, positive airway pressure, polysomnography
sleep state, breathing,
tonsils,
adenoids,
continuous
stupid-lazy child who frequently suffers from headaches at school, breathes through his mouth instead of his nose, snores and is restless at night, and wakes up with a dry mouth in the morning, is well worthy of the solicitous attention of the school medical officer.“
“The
Correspondence to be addressed to: Robert T. Brouillette, MD, 2300 Tupper Street, C-920, Montreal, Quebec, Canada, H3H lP3. (Fax: 514-934-4356; email: [email protected]) 1087-0792/98/040255
+ 15 $12.00/O
0 1998 W.B. Saunders
Company
Ltd
256 Table 1
V. Kirk
The severity spectrum for pediatric
Reproduced from Broillette RT, Waters how safe? how effective? Am J Respir
et al.
sleep-related
upper airway obstruction
K. Oxygen therapy for pediatric obstructive Crit Care Med 1996; 153: 1-2, with permission.
sleep
apnea
syndrome:
This nineteenth-century reference was published in an article entitled “On some causes of backwardness and stupidity in children” [l] and describes the unfortunate sequelae resulting from lack of recognition and treatment for the common disease we now know as the pediatric obstructive sleep apnea syndrome (OSAS). OSAS was initially described in the medical literature in 1966 as a breathing disorder during sleep affecting an obese adult male [2]. At this time, the pediatric medical community had not yet recognized the diagnosis of OSAS; however, several pediatric cases of hypertrophied tonsils and adenoids causing congestive heart failure and car pulmonale were reported [3,4]. It was not until 1976 that the first case reports of obstructive sleep apnea in children were published [5]. Since then, OSAS in children has been the focus of much attention and research and is now widely accepted as a significant cause of morbidity in childhood. North American epidemiological data on OSAS in childhood are not currently available; however, the prevalence in England of OSAS amongst children aged 4-5 years is estimated at 0.7% [6]. The peak incidence is in the 2-5-year-old age group. There is no male preponderance, as seen in adult OSAS [7,8]. Untreated, OSAS contributes to a variety of important medical and developmental problems including failure to thrive, cardiopulmonary disease, and developmental delay. This review describes the presentations and associations of OSAS in children. Key elements of the history and physical exam that will alert the clinician to a possible diagnosis of OSAS are reviewed. Discrimination between benign snoring in childhood and those children requiring further investigation is discussed. A review of diagnostic investigations and a brief summary of current treatment modalities is also included.
Definition OSAS in childhood, as defined by the American Thoracic Society, is a disorder of breathing during sleep characterized by prolonged partial upper airway obstruction and/or intermittent complete obstruction, obstructive apnea, that disrupts normal ventilation during sleep and normal sleep patterns [9]. A spectrum of severity related to the degree of upper airway resistance, the duration of the disease, the presence or absence of hypoxemia episodes and to certain clinical features has been suggested by
Sleep apnea in children
Reproduced diagnostic permission.
from Brouillette RT, Hanson D, David R, Klemka L, Szatkowski approach to suspected obstructive sleep apnea in children. ]
257
A, Fembach
S, Hunt
Pediatr 1984; 105: 10-14,
C. A with
Brouillette and Waters [lo] (Table 1). At one end of the spectrum (Grade 0) is snoring with no associated abnormalities or morbidities. Snoring has been estimated to occur in 7-12% of children [11,12]. At the opposite end of the spectrum are those children with severe disease and evidence of end-organ damage due to severe and prolonged hypoxemia and airway obstruction (Grade 5). Most children present to medical attention at intermediate stages with definite obstructive apnea, with or without associated hypoxemia (grades 4 or 3, respectively). Many children with OSAS have either continuous or prolonged partial airway obstruction associated with clinical manifestations consistent with OSAS; often they do not fit the criteria for diagnosis established for OSAS in adults. For this reason, adult criteria for diagnosis, e.g. an apnea index >5/h, are not applicable to the pediatric population [13]. Diagnosis is based on clinical features and quantitative assessment of respiratory and gas exchange patterns during sleep.
Presentation The wide range of signs and symptoms associated with OSAS in children is a consequence of the variability in developmental stages, the variable severity, and the diversity of underlying etiologies. The most common etiology of OSAS in otherwise normal children is adenotonsillar hypertrophy. Comparison of 23 children with confirmed OSAS due to adenotonsillar hypertrophy with 46 age- and sex-matched healthy controls showed increased frequencies of several symptoms (Table 2) [14]. The three most predictive symptoms associated with OSAS are loud snoring, difficulty breathing during sleep, and sleep-related pauses in breathing witnessed by the parents [14]. Children may also experience frequent arousals during sleep due to OSAS, although
V. Kirk
258
RUs
et al.
1;
1
pus
RDS
pDS
Upstream segment
Collapsible
segment
Figure 1 Starling resistor model of upper airway. Upper airway is represented as tube with collapsible segment. Segments upstream (nasal) and downstream (tracheal) from collapsible segment have fixed diameters and resistances (Rus and R,) and pressures (Pus and I’&, respectively. Collapse occurs when the pressure surrounding the airway (P,,,t) becomes greater than pressure within the airway. (Reproduced from Marcus CL, McColley SA, Carroll JL, Loughlin GM, Smith PL, Schwartz AR. Upper airway collapsibility in children with obstructive sleep apnea syndrome. I Appl Physiol 1994; 77: 918, with permission.)
more recent data suggests that sleep architecture is relatively well preserved in children with OSA as compared to adults [15]. Enuresis has been reported to occur more frequently in children with OSAS but is a useful clinical sign only if the child previously has been dry at night [3,14,16,17]. Daytime symptoms that may be associated with OSAS include disorientation on waking, morning headaches, and mood and personality changes. An “adenoidal facies” and/or pectus excavatum may be present on examination of the awake child 118,191.
Pathogenesis Two hypotheses have been suggested to explain the pathogenesis of OSAS in children and adults. The StarZing resistor principle has been proposed to explain the frequent occurrence of partial upper airway obstruction associated with flow limitation (Fig. 1) [20,21]. During inspiratory flow limitation, airflow is determined by pressuregenerating changes resistance upstream (for instance at the adenoid-palate level) from the collapsible segment (pharynx); airflow is not augmented by increased negative pressure downstream (esophageal pressure), even when inspiratory pressure-generating muscles contract forcefully. Airflow limitation can be recognized on polysomnography by a,flattening of the nasal airflow tracing during mid-inspiration (Fig.
1) POI. During activation
inspiration a negative pressure is generated within the pharynx due to of the diaphragm and intercostal muscles [22]. Collapse of the upper airway
Sleep apnea in children
open
Neck
-4 flexion
Neck
259
extension
Figure 2 A model of pharyngeal airway maintenance illustrating the opposite forces that affect airway diameter. Airway constricting (suction force) and airway dilating forces (pharyngeal muscles) are shown on either side of a fulcrum. The balance of forces is dynamic. A decrease in pharyngeal dilating muscular force during REM steep can contribute to airway closure. (Adapted from Thach BT. Potential role of airway obstruction in SIDS. In Krous H, Culbertson H (eds). Sudden Infint Death Syndrome. Baltimore, MD: Johns Hopkins Press 1988, with permission.)
Table 3
Anatomical
factors predisposing
to OSAS in children
due to the force of this negative pressure is prevented by simultaneous activation of oropharyngeal dilator muscles such as the genioglossus muscle that protrudes the tongue [22,23]. According to the balance offerces hypothesis, OSAS occurs whenever an imbalance in these forces favors negative oropharyngeal pressures during inspiration [22,23] (Fig. 2). Anatomic factors that increase resistance to airflow therefore predispose to OSAS. The most common anatomical factor in children is adenotonsillar hypertrophy
260
Table 4 Functional
V. Kirk et al. causes of OSAS in children
but there are numerous nasal, pharyngeal and craniofacial abnormalities that occur less frequently (Table 3). Functional abnormalities also contribute to OSAS in children. The structure of the upper airway may be normal on physical examination, but if coordinated activation of both inspiratory and oropharyngeal dilator muscles does not occur during inspiration, OSAS will occur. The most common functional process contributing to OSAS is rapid eye movement (REM) sleep. During this stage of sleep, phasic muscle activity of the oropharyngeal muscles may be significantly depressed. Diaphragmatic activation continues to generate negative oropharyngeal pressures but tone in the upper airway tissues is reduced, leading to increased upper airway resistance and partial or complete airway obstruction during inspiration. In a recent series of pediatric evaluations for OSAS, the median apnea/hypopnea index was 6.5 versus 0.8 events/h in REM and non-REM sleep, respectively [24]. Other functional factors contributing to pediatric OSAS include abnormalities of neural function and drugs which depress the central nervous system (Table 4) 1251. Obstructive apnea associated with prematurity is reviewed elsewhere [26]. Many children with OSAS have a complex interaction of both anatomical and functional abnormalities.
Sequelae It is important to identify the presence of OSAS and to determine accurately the etiological factors to ameliorate the significant morbidity’that can result from inadequate
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261
Table 5 Sequelae of OSAS in children
treatment (Table 5). Cor pulmonale, pulmonary hypertension, and congestive heart failure characterize the most severe and prolonged cases of pediatric OSAS. Similarly, repetitive, severe asphyxial episodes and sleep disturbance clearly interfere with the normal development and functioning of the child. Secondary enuresis is frequent in children with OSAS and has been shown to resolve with treatment of the OSAS [27]. However, much more work needs to be done on the early identification of neurobehavioral sequelae of pediatric OSAS. Poor growth velocity associated with adequate caloric intake and absence of chronic illness (failure to thrive) is a frequent consequence of OSAS in children. The underlying mechanism is not well established but current hypotheses include the presence of a hypermetabolic state during sleep. In a recent article by Marcus et al. energy expenditure during sleep was shown to decrease significantly following adenotonsillectomy for OSAS. There was an increased post-operative weight gain without a significant change in caloric intake [28]. Alternatively, it has been suggested that nocturnal hypoxemia affects the neurohormonal balance of hypothalamic hormones required for adequate growth. Growth hormone secretion normally occurs during sleep and may be decreased due to frequent arousals. Nasal obstruction, due to chronic rhinitis or adenotonsillar hypertrophy, alters the senses of taste and smell and thus may diminish appetite. It is also more difficult for chronic mouth breathers to eat and breathe at the same time and some children with very large tonsils have difficulty swallowing. A complex interaction of factors in OSAS is most likely responsible for failure to grow adequately. Importantly, growth usually accelerates after adenotonsillectomy in children with OSAS (Fig. 3). Although there is increasing epidemiological evidence implicating OSAS as a risk factor for systemic hypertension in adults, the literature in children is scant and conflicting. Guilleminault et al. reported the presence of diurnal systemic hypertension in 10% of 50 children with OSA, all of whom were older than 10 years [29]. More recently, however, Kunzman et aI. were unable to show any abnormalities in diastolic or systolic arterial pressures in their group of 22 children [30].
262
V. Kirk
et al.
5
1
2 Age
3 (years)
4
5
6
Figure 3 Shown are the weight curves of six patients with failure to thrive caused by OSA. In two patients, adequate data were available to reconstruct pre-operative curves (---). Note the rapid weight gain (“catch-up growth”) after surgical relief of airway obstruction (-). Fifth and ninety-fifth percentiles for normal children are shown. (Reproduced from Brouillette RT, Fernbach SK, Hunt CE. Obstructive sleep apnea in infants and children. J Pedintr 1982; 100: 31, with permission.)
Diagnostic
approach
Making the diagnosis of OSAS in children begins with a thorough history. Special attention must be paid to details of sleep, a period of time generally ignored in a routine medical interview. Ask specifically about snoring, difficulty breathing or periods of no apparent breathing. Inquire about usual sleep position as some children with OSAS adopt peculiar postures during sleep to maximize airway patency. Pay particular attention to children with obvious craniofacial abnormalities or Down’s syndrome to determine when these high-risk patients require further investigations. Presence of enuresis, especially if recent in onset, and changes in appetite or eating habits should be recorded. Additionally, changes in behaviour or school performance, including relevant teacher reports, should be sought. A thorough ear, nose and throat exam, including a search for a deviated nasal septum, nasal polyps or rhinitis, should be performed. Tonsillar size and general oropharyngeal anatomy should be examined for signs of abnormality such as a bifid uvula, suggestive of an underlying cleft palate.The cardiovascular exam is such as digital clubbing, a right directed towards evidence of car pulmonale, ventricular heave, a displaced point of maximal impulse, loud second heart sound, or a murmur suggestive of tricuspid regurgitation. Pulmonary exam should include observation for increased work of breathing while awake, presence or absence of cyanosis, and description of breathing rate and pattern.
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263
The most frequent abnormalities on physical exam are tonsillar enlargement and inability to breathe through the nose, representing adenoidal nasal obstruction. However, the exam performed with the child awake is often completely normal. Ideally, the examiner should observe any child suspected of having OSAS while the child is asleep. At times the child with severe OSAS will fall asleep in the office facilitating examination in the most symptomatic state. Alternatively, asking the parents to obtain an audio or audio-visual tape of the child sleeping may prove to be an efficient means of observing the child asleep. Whether such recordings are representative or worst case data should be ascertained. The differential diagnosis of sleep disruption in children includes other medical and developmental disorders that should be considered. Gastroesophageal reflux, asthma, and seizure disorders can usually be ruled out by careful history and physical examination of the child. Developmental problems, such as parasomnias (night terrors, confusional arousals, sleep-walking) can also cause sleep disruption and are generally easily distinguished from OSAS. These disorders can also co-exist in patients with OSAS, making the diagnosis more challenging. For children with a history and/or physical examination suggestive of obstructive sleep apnea, the gold standard investigation for confirmation of both diagnosis and disease severity is overnight polysomnography (PSG). Studying children in this manner presents unique challenges. Skilled and experienced technicians are essential in order to win the cooperation and trust of young children. The laboratory setting must be soothing, and non-threatening. A typical hospital sleep laboratory setting may frighten a child, thus preventing the technicians from obtaining even the most elementary set-up. Removing all non-essential hospital equipment from the immediate area, the display of colorful and interesting posters, diversion with favorite video shows and a relaxed, non-threatening approach to lead application all help to gain the cooperation of the child. Parents should be encouraged to bring favorite toys or items from home that may help to create normal bed-time routines in the sleep laboratory. We strongly recommend that a parent be required to stay with the child overnight, as the child may waken and require parental attention in order to re-establish sleep. The American Thoracic Society recently established standards and criteria for cardiopulmonary sleep studies in children. These include measurements of respiratory movements, airflow, ventilation and oxygenation, sleep staging, electrocardiogram, electromyogram and audiovisual recording. Supervision by a trained technician is required throughout the study with additional record keeping of unusual events or behaviours during the night [9]. Additional information regarding sleep positioning, snoring, and arousal frequency is easily obtained by adding videotaping during PSG. Normal values for polysomnography in children and adolescents were reported by Marcus et al. (Table 6) [31]. Unfortunately, few scientific data examining the correlation between PSG abnormalities, clinical symptoms, and sequelae of OSAS in children are currently available. The American Thoracic Society recommended further investigation of abbreviated testing, such as unattended home monitoring of oxygen saturation and respiratory pattern. In Montreal, home cardiopulmonary sleep studies were shown to be an accurate and practical alternative to overnight laboratory polysomnography for routine evaluation of non-complex children with adenotonsillar hypertrophy [32]. Adjunctive diagnostic investigations include airway imaging studies such as radiography, or rarely fluoroscopy, of the lateral neck and computed tomography
264
Table 6 Normal
V. Kirk
polysomnographic
et al.
values for children
and adolescents
*Increase in CO, during sleep; tTST= total sleep time. Reproduced from Marcus CL, Omlin KJ, Basinki DJ, Bailey SL, Rachal AB, Van Pechmann WA, Keens TG, Davidson-Ward SL. Normal polysomnographic values for children and adolescents. Am Rev Respir Dis 1992; 146: 12351239, with permission. For additional normal values in children, see also chapter 9 in [43].
of the upper airway for assessment of the choanae and anterior nares. Standard lateral neck radiographs done with the patient awake will identify enlarged adenoids and/or tonsils and occasionally other structural causes of upper airway obstruction. Fernbach et al. noted that 18 of 26 patients with OSAS were correctly identified as having adenotonsillar enlargement on plain radiograph. Subsequent upper airway fluoroscopy, performed with the patients asleep, identified the site of obstruction in 100% of these patients [33]. The relative ease with which a plain radiograph can be obtained makes it a useful adjunct to identify contributing airway abnormalities in OSAS. Fluoroscopy should be reserved for those patients in which the site of airway obstruction is not evident on plain radiograph. In selected patients with evidence of upper airway obstruction, rhinoscopy may be useful in identifying the site [34]. Investigation of children with severe OSAS should also include diagnostic studies for evidence of right ventricular hypertrophy (RVH), pulmonary hypertension, and car pulmonale. This generally involves chest radiograph for assessment of cardiac size, electrocardiogram and frequently echocardiography. Tal et al. reported that the most sensitive diagnostic test for RVH and pulmonary hypertension due to car pulmonale is ventricular scan [35]. They assessed 27 children with OSAS using radionuclide ventriculography and compared the results to those obtained with conventional methods, electrocardiogram and chest radiograph. Cardiac involvement was correctly identified by conventional investigations in only two of 10 patients with abnormal scans. Most importantly, all patients showed improvement on cardiac scans following adenotonsillectomy [35]. Results of echocardiography are variable between centers and operators. Therefore, it is prudent to involve the cardiologists available to you in the decision-making process regarding optimum cardiac investigations. It is also important to consider the diagnosis of OSAS in children who present with unexplained congestive heart failure, pulmonary hypertension or car pulmonale. An early morning blood gas may demonstrate an elevated bicarbonate suggesting a compensated respiratory acidosis; however, a normal morning blood gas does not exclude the presence of nocturnal hypoventilation or hypoxemia. Patients with OSAS who also have prolonged central apnea should undergo imaging studies of the brainstem, most accurately performed by magnetic resonance imaging. Particular attention should be directed to the brainstem and cervico-medullary junction for evidence of a Chiari malformation or space-occupying lesion.
Sleep apnea in children
265
Practice Points
Treatment Adenotonsillectomy is the most common therapy for OSAS in children; however, the treatment for a particular child depends on the underlying abnormalities, the site of obstruction, and the presence or absence of contributing neurological or functional abnormalities. Table 7 reviews possible approaches to treatment. Pharmacological therapy with oral steroids is useful for management of acute airway obstruction due to tonsillar enlargement from infectious mononucleosis; however, administration of moderate doses to patients with OSAS due to adenotonsillar hypertrophy for 5 days was not effective [36]. The search for a medical alternative to adenotonsillectomy should continue as the surgical procedure can be associated with complications, particularly post-tonsillectomy bleeding. The use of nasal CPAP in children with OSAS has been very successful in experienced hands [37,39]. The major indication in children is persistence of OSAS following adenotonsillectomy. Nasal CPAP has also been used for peri-operative stabilization of some patients as airway obstruction may persist immediately postoperatively due to soft-tissue swelling and effects of sedatives and anesthestics [37]. Children with documented severe OSAS are at increased post-operative risk for airway compromise. Rosen et ~2. reported a complication rate of 27% in 37 children undergoing adenotonsillectomy for OSAS. Those children having post-operative complications were more likely to have additional underlying medical conditions such as
266 Table 7
V. Kirk et al. Treatment
of obstructive
sleep apnea in children
craniofacial anomalies, hypotonia, obesity, previous airway trauma, car pulmonale or failure to thrive [40]. The authors recommended overnight observation with an apnea monitor and oximeter for those patients with the additional abnormalities listed above, those under 2 years of age, and those with polysomnographic findings of severe OSAS (Grade 4 or 5). Some patients with no previous evidence of cardiac failure may develop acute pulmonary edema following relief of airway obstruction. Therefore, judicious use of intravenous fluids and frequent post-operative observation are essential.
Research
issues
OSAS in children is a relatively new diagnostic entity and several issues regarding diagnosis, treatment, and sequelae are not yet well studied. The role for abbreviated testing in the home or hospital setting is not well established. The timing of initial testing for children known to be at high risk of OSAS has not been identified. Behaviour and learning difficulties associated with OSAS and the effects of early diagnosis and treatment on these specific problems have not yet been well studied. It remains poorly understood why some children have benign snoring not associated with OSAS and what effects this may have on development and sleep. Upper airway resistance syndrome (UARS) has been identified in adults as a significant cause of morbidity with signs and symptoms of OSAS associated with normal polysomnographic findings. The presence and significance of UARS in children is not yet well defined and requires further study [41,42]. Although a short course of systemic steroids does not appear to have a significant effect on OSAS in children, a recent report of inhaled nasal corticosteroid use in children with adenotonsillar hypertrophy is promising and should be confirmed with further study [34]. As the bacteriology of adenotonsillar hypertrophy becomes better understood, new antibiotics may deserve a clinical trial. Some clinicians are now advocating the use of nasal CPAP for pre- and post-operative stabilization and treatment
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267
of children with OSAS undergoing adenotonsillectomy or UPPl? Optimal peri-operative management of these children is a particularly pressing issue. In many institutions across North America, children undergoing adenotonsillectomy are discharged home within hours of the procedure. Identification of those children at risk of postoperative complications is imperative in order to avoid unnecessary tragedies.
Conclusion OSAS is a significant and treatable cause of morbidity in children. Timely diagnosis is dependent on maintaining an index of suspicion for high-risk children and on establishing a set of routine screening questions regarding sleep habits that can be easily incorporated into routine pediatric and family medicine practice. Further study is required regarding the significance of UARS in children, non-surgical treatment modalities for OSAS, and effects of OSAS on behaviour and learning. High-risk children undergoing surgical correction for OSAS require close post-operative monitoring and may also benefit from peri-operative use of nasal CPAP. Practice Points
V. Kirk et al.
268
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29 Weider DJ, Sateia MJ, West RF’. Nocturnal enuresis in children with upper airway obstruction. Otolayngol Head Neck Surg 1991; 105: 427432. 30 Kunzman LA, Keens TG, Davidson-Ward SL. Incidence of systemic hypertension in children with obstructive sleep apnea syndrome (abstr.) Am Rev Respir Dis 1991; 141: A808. 31 Marcus CL, Omlin KJ, Basinki DJ, Bailey SL, Rachal AB, Von Pechmann WA, Keens TG, Davidson-Ward SL. Normal polysomnographic values for children and adolescents. Am Rev Respir Dis. 1992; 146: 1235-1239. 32 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: 241-252. 33 Fernbach SK, Brouillette RT, Riggs TW, Hunt CE. Radiologic evaluation of adenoids and tonsils in children with obstructive sleep apnea: plain films and fluoroscopy. Pediatr Radio1 1983; 13: 258-265. 34 Demain JG, Goetz DW. Pediatric adenoidal hypertrophy and nasal airway obstruction: reduction with aqueous nasal beclomethasone. Pediatrics 1995; 953: 355-364. 35 Tal A, Leiberman A, Margulis G, Sofer S. Ventricular dysfunction in children with obstructive sleep apnea: radionuclide assessment. Pediatr Pulmonol 1988; 4: 139-143. 36 Al-Ghamdi SA, Manoukian JJ, Morielli A et al. Do systemic corticosteroids effectively treat obstructive sleep apnea secondary to adenotonsillar hypertrophy? La yngoscope 1997; 197: 1382-1387. 37 Waters KA, Everett F, Bruderer F, MacNamara F, Sullivan CE. The use of nasal CPAP in children. Pediatr Pulmonol 1995; Sll: 91-93. 38 Waters KA, Everett FM, Bruderer JW, Sullivan CE. Obstructive sleep apnea: the use of nasal CPAP in 80 children. Am 1 Respir Crit Care Med 1995; 152: 780-785. 39 Marcus CL, Davidson-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. 40 Rosen GM, Muckle RI’, Mahowald MW, Goding GS, Ullevig C. Postoperative respiratory compromise in children with obstructive sleep apnea syndrome: Can it be anticipated? Pediatrics 1994; 935: 784-788. 41 Guilleminault C, Stoohs R. Chronic snoring and obstructive sleep apnea syndrome in children. Lung 1990; Suppl. 912-919. 42 Guilleminault C, Philip I? Polygraphic investigation of respiration during sleep in infants and children. J Clin Neuropkysiol 1992; 91: 48-55.