1204 7'horax 1995;50:1204-1210

Sleep-related disorders * 6 Thorax: first published as 10.1136/thx.50.11.1204 on 1 November 1995. Downloaded from Series editor: P M A Calverley

Obstructive apnoea syndrome in infants and children: established facts and unsettled issues

C Gaultier

The obstructive sleep apnoea (OSA) syndrome months to six years) estimated the prevalence was first identified in infants and children by ofOSA at 1 -6-3.4%.8 Large scale, well designed Guilleminault et al in 1976.' Since then, a studies assessing the prevalence of an increased great deal has been learned about infancy and upper airway resistive load during sleep in in- childhood obstructive apnoea, although several fants and children are needed. A reasonable areas remain largely unexplored. Since the first priority would be to develop and validate a description of the OSA syndrome during in- questionnaire, use it in the general population fancy and childhood, we have learnt that the to detect high risk individuals, and subject these clinical symptoms of an increased upper airway to polysomnographic recordings. resistive load during sleep are not always as- sociated with complete airways obstruction during sleep.2 Episodes of partial airways ob- Clinical symptoms struction without obstructive apnoea are fre- A careful history of sleep-associated symptoms quently observed in infants and children,3 so is the first step in detecting a sleep-related adult diagnostic criteria for the OSA syndrome increase in upper airway resistive loads in an may not identify infants and children with infant or child. However, more than a year http://thorax.bmj.com/ sleep-related increases in upper airway resistive often elapses between the onset of symptoms loads.34 As recommended by Carroll and and diagnosis. This explains why severe com- Loughlin,4 we should consider that infancy and plications such as cardiorespiratory failure are childhood OSA syndrome is not a form of adult sometimes the presenting complaint.9 OSA but a separate syndrome with specific Clinical symptoms in children differ in sev- symptoms, diagnostic criteria, and therapeutic eral ways from those in adults. Excessive requirements. daytime sleepiness, the typical presenting complaint in adults, is not frequent in children.4 on September 28, 2021 by guest. Protected copyright. The two major symptoms are sleep-related Prevalence breathing difficulties and ."910 Parents We still know little about the prevalence of sometimes report that during sleep their child increased respiratory resistive loads during stops breathing, sweats profusely, is restless, sleep in infants and children. Reliable data on and assumes unusual positions in an attempt the incidence of the OSA syndrome during to relieve upper airways obstruction. Enuresis infancy and childhood are not available. Series has been reported in children with the OSA ofpatients with OSA published in the paediatric syndrome." Mouth breathing during wake- medical literature suggest that the peak in- fulness is common when nasal obstruction is cidence is in the 2-5 year age group. This age severe. Upper respiratory tract infections are group may be particularly susceptible to OSA frequently reported in young children.9"0 The because of the prominence of pharyngeal severity of the symptoms usually increases dur- lymphoid tissue during these years.5 In chil- ing these infections and decreases after re- dren, in contrast to adults, there is no clear covery. Behavioural disorders, including male predominance of OSA.4 hyperactivity, aggressiveness, and rebellious be- The prevalance of snoring in two large popu- haviour, have been reported.91012 In school age lations of children has been evaluated by children learning problems may occur." How- questionnaire.67 Between four and six years of ever, it should not be concluded that a sleep- age the reported prevalence of snoring was related increase in upper airway resistive loads In one of these studies children aged invariably causes behavioural abnormalities. Laboratory of 7-10%.7 Physiology, Hospital 4-5 years were studied at home by overnight Psychological testing before and after treatment Antoine Beclere, video recording and oximetry.7 The prevalence can be useful for determining the contribution Faculty of Medicine of sleep and breathing disorders in this age of upper airway problems to behavioural ab- Paris XI, 92141 Clamart, France group was estimated at 0O7%. Another ques- normalities. C Gaultier tionnaire based study in a wider age range (six Obesity has been reported in a large pro- Obstructive sleep apnoea syndrome in infants and children 1 205 portion of adults with OSA but has been found adenoidectomy and tonsillectomy Wilkinson et in only a few of the patients in paediatric al found electrocardiographic evidence of right series.4 The risk ofoccurrence ofa sleep-related ventricular hypertrophy in only 3 3% ofcases." Thorax: first published as 10.1136/thx.50.11.1204 on 1 November 1995. Downloaded from increase in upper airway resistive loads is not Thus, available data do not provide an adequate clearly established in obese children. However basis for estimating the prevalence of right an abnormally high prevalence of OSA without ventricular dysfunction in infants and children clinical symptoms has been found in overweight with complete and/or partial upper airways infants."4 In obese children both low and high obstruction during sleep. Interestingly, low pre- percentages of sleep-disordered breathing have treatment right ventricular ejection fraction val- been reported. 516 Silvestri et all6 recommended ues have been shown to increase significantly that obese children with a history of sleep- after tonsillectomy.'4 Recently developed echo- related breathing difficulties should be referred cardiography techniques allow examination of for polysomnographic evaluation. interventricular septum behaviour during Failure to thrive is a not unusual char- sleep-related upper airways obstruction. In one acteristic of infants with OSA.49 Investigations 11 year old child Guilleminault et al reported to look for a sleep-related increase in upper a leftward shift of the septum, even during airway resistive loads should be routinely per- heavy snoring.'5 In a preliminary study the formed as part of the evaluation of growth severity of clinical symptoms and/or poly- retarded infants and children and adequate somnographic abnormalities was not related treatment of the upper airways obstruction to the presence of echocardiographic ab- results in rapid catch-up growth.9 The mech- normalities.'6 anisms of growth retardation are not well un- Systemic hypertension is found in a large derstood but may include an increase in the percentage of adult patients with the OSA syn- metabolic rate during sleep. In a recent pre- drome.4 In a series of 50 cases diurnal systemic liminary study oxygen consumption during hypertension was found in 10% of patients, all sleep decreased after treatment in children with of whom were older than 10 years.'3 More OSA.'7 These data suggest that children gain recently, no abnormalities in systolic or diastolic weight after treatment because of a decrease in arterial pressures were observed in 22 children energy expenditure and that before treatment aged 6 (0 4) years.'7 Non-invasive continuous the increase in the work of breathing during blood pressure measurements were performed sleep is responsible for an increase in the con- in two children whose fingers were big enough sumption of oxygen by respiratory muscles, to allow use of a cuff designed for adults and leaving less oxygen available for growth. pulsus paradoxus was found in one.'5 Alternatively and/or simultaneously, repeated There are conflicting data with regard to interruption of sleep may intefere with the re- ECG abnormalities in children with the OSA lease of growth hormone. One study showed syndrome. A study carried out in the early normalisation of growth hormone release 1980s in a group of 50 children with OSA http://thorax.bmj.com/ after treatment of upper airways obstruction.'8 found sinus arrests lasting from 2-5 to 9 seconds in 52% of cases, second degree atrioventricular block in 28%, and paradoxical tachycardia in Cardiovascular complications 16%.'3 However, a more recent study in 12 The syndrome combining hypoventilation, pul- subjects aged eight months to 14 years with monary hypertension, cor pulmonale, and pul- complete and/or partial airways obstruction monary oedema was described in the middle of during sleep failed to find significant changes in the 1960s in infants and children with chronic heart rate during numerous episodes of severe on September 28, 2021 by guest. Protected copyright. upper airways obstruction.'9 Sofer et al'0 de- hypoxaemia.'8 No episodes of severe brady- scribed the haemodynamics of this syndrome cardia or cardiac arrhythmia were detected. in a 22 month old child and suggested that the These findings are of clinical relevance since pulmonary oedema was secondary to both right ambulatory ECG monitoring has been used in and left heart failure. In their patient pulmonary adults to screen for sinus brady-tachy- arterial pressures returned to normal within 48 arrhythmia as a marker for OSA.'9 The data hours ofsurgery. Acute cardiorespiratory failure suggest that this method would not detect all seems to occur mainly in patients with long- children with increased upper airway resistive standing neglected clinical symptoms. Upper loads during sleep. respiratory tract infection is usually the trig- Finally, a recent study ofheart rate variability gering event. Patients with an unrecognised evaluated by power spectral analysis dem- sleep-related increase in upper airway resistive onstrated a predominance of sympathetic ac- loads are still at risk of acute cardiorespiratory tivity throughout the night with surges during failure. Paediatricians should be aware of this periods with apnoeas.30 This might indicate an potential complication because it can result in increased risk of systemic hypertension at an sudden death."" older age in the event ofpersistent sleep-related Cardiovascular symptoms are common in breathing disorders. adults with the OSA syndrome. It is therefore of interest to review their frequency in infants and children without cardiac failure. However, Methods of diagnosis data on this issue are scant. Radiological and/ A standardised questionnaire developed by or electrocardiographic evidence of right vent- Brouillette et al" has proved useful for sus- ricular hypertrophy was reported in 55% of a pected OSA in children aged one to 10 years. group of infants and children with OSA.'93" In However, more recently Carroll et al reported contrast, in a series of 92 children referred for that primary snoring cannot be differentiated 1 206 Gaultier from OSA by clinical history alone in children.32 sleep. Associated with obstructive apnoeas, In a population of infants with an abnormal polygraphic recording shows laboured breath- obstructive apnoea index Kahn et al found ing during the ventilatory periods. Wide swings Thorax: first published as 10.1136/thx.50.11.1204 on 1 November 1995. Downloaded from that a history of profuse sweating and noisy in oesophageal pressure have been found dur- breathing during sleep in the absence of upper ing ventilatory periods.4647 Paradoxical inward respiratory infection was useful as an aid to the motion during inspiration has been diagnosis of sleep-related obstructed breathing reported throughout REM sleep periods in chil- episodes in infants.33 Thus, there is no con- dren and during non-REM sleep.48 Accessory sensus on whether or not an age-specific ques- respiratory muscles, including abdominal tionnaire is an adequate tool for identifying muscles, are recruited during non-REM sleep infants and children with increased upper air- with snoring.49 Compared with non-REM way resistive loads during sleep. sleep, REM sleep is associated with inhibition Polysomnographic examination remains the of accessory respiratory muscle activity which gold standard diagnostic investigation. How- results in an increase in the diaphragmatic work ever, a full overnight polysomnographic study of breathing. is technically difficult and can be performed Guilleminault et al were the first to point only by trained personnel. Some laboratories out in 1982 that some children with clinical study a daytime nap. One study compared nap symptoms do not have obstructive apnoeas and overnight polysomnography recordings in during sleep.2 However, these children have 40 children aged one month to 16-3 years, significantly increased respiratory resistive two thirds of whom received chloral hydrate loads during sleep and wide swings in oeso- sedation for the nap polysomnography.34 The phageal pressure. Their breathing is most results showed that nap studies had a sensitivity laboured during REM sleep. Recently, Rosen of 74%, a specificity of 100%, a positive pre- et al3 documented partial airways obstruction dictive value of 100%, and a negative predictive during sleep in a group of 20 patients aged value of 17% for the diagnosis of sleep-dis- eight months to 16 years; 80% of their patients ordered breathing. Thus, a negative nap study had sustained partial airways obstruction char- does not rule out the diagnosis and must be acterised by cyclic decreases in Sao2, hyper- completed by an overnight sleep study. Natural carbia, laboured paradoxical respiratory efforts, sleep for a daytime polysomnographic study is and snoring. Such episodes of partial air- sometimes difficult to obtain. Sleep deprivation ways obstruction are described as obstructive or sedation has been used to induce daytime hypopnoeas in adult patients.50 However, there sleep. However, sleep deprivation has been is no consensus among laboratories on the shown to increase significantly the number of definition of obstructive hypopnoea. Studies obstructive respiratory events in healthy in- are needed to determine the clinical usefulness fants,35 and sedation by chloral hydrate of oesophageal pressure measurements during is sometimes associated with a dramatic sleep in symptomatic infants or children with http://thorax.bmj.com/ worsening of upper airways obstruction.3637 no obstructive apnoeas on polysomnographic Use ofhome monitoring using either a micro- recordings. However, data on the normal range phone38 or video recording and oximetry3940 of oesophageal pressure swings during sleep in has been suggested. However, none of these children are scant. The lowest negative oeso- techniques has been validated against overnight phageal pressures have been reported to range polysomnography in a large number ofsubjects from -8 to -20 cm H20 in two groups of with different levels of severity of OSA. More healthy children aged 2-14 years.247 work is needed to verify the reliability of am- Early studies in children with the OSA syn- on September 28, 2021 by guest. Protected copyright. bulatory methods of diagnosis of sleep-related drome found abnormalities in the sleep pattern resistive load increases in infants and children. with a decrease in the duration of slow wave sleep.'3 These findings were not borne out by recent investigations in which the sleep pattern Polysomnographic findings was normal.5' Differences in the severity and There are few data on the occurrence of ob- duration of the disease may at least partially structive apnoea during overnight sleep in nor- explain these discrepancies. mal infants and children. In infants older than Different categories of arousal have been six weeks the index of obstructive apnoea epi- characterised, such as behavioural arousal, sodes lasting more than three seconds was EEG arousal, and movement arousal.52 How- found to be less than 1.4142 No episodes of ever, several laboratories are still working on obstructive apnoea were detected in children43 the development of standardised criteria for or in a small group of adolescents." However, arousal detection in infants and children. Few in a more recent study of 50 children aged reports have documented the occurrence of 1-18 years there were 0-1 (0 5) (range 0-3.1) arousal at the end of sleep-related obstructive obstructive apnoeas lasting less than 10 seconds events in infants or children. In a study of per hour of total sleep time.45 We clearly need preterm infants with apnoeas, behavioural more normative data to improve our ability to arousal occurred more frequently after ob- interpret polysomnographic data in paediatric structive apnoeas than after central apnoeas,53 patients. but no attempt was made to characterise EEG Polysomnographic recordings can be divided arousal. An important study in infants with into two categories - those with and those increased upper airway resistive load during without obstructive apnoeas. When obstructive sleep found an abnormal number of EEG apnoeas are found, their duration and rate of arousals compared with age matched control occurrence are usually greatest during REM infants.54 Interestingly, EEG arousals occurred Obstructive sleep apnoea syndrome in infants and children 1207

at the nadirs of the oesophageal pressure re- dren with OSA.66 Closing pressure is increased cording. In a group of prepubertal children in children with OSA compared with age with OSA the end of non-REM sleep apnoea matched subjects with primary snoring; similar Thorax: first published as 10.1136/thx.50.11.1204 on 1 November 1995. Downloaded from was marked by EEG arousal in 12% of events findings have been reported in adults.67 In- and by movement arousal in the remaining terestingly, closing pressure was lower in chil- events.49 During REM sleep only movement dren than in adults with snoring, suggesting arousals occurred.49 Another study reported a differences in upper airways collapsibility similar low rate of occurrence of EEG arousal between children and adults. Further in- in children and adults.55 The fact that EEG vestigations are needed to document changes and behavioural arousals are uncommon in in the mechnical properties ofthe upper airways children may be related to the less frequent in healthy children. Currently, data are avail- occurrence of excessive daytime sleepiness in able only in healthy infants.68 Little attention children than in adults.4 However, more ex- has been paid to the functional and anatomical tensive multicentre studies using standardised consequences of chronic obstruction on the criteria for arousal detection and assessment of growth of the upper airways. Experiments in daytime behavioural disturbances are needed rhesus monkeys have demonstrated inter- in different age groups of infants and children actions between abnormal nasal breathing with increased upper airway resistive loads. and abnormal growth of the mandible starting at birth.69 These environmental factors may explain why residual symptoms are sometimes Pathophysiology seen after tonsillectomy70 and why symptoms The pathophysiology ofincreased upper airway can recur after puberty.7" Finally, a racial pre- resistive load in infants and children is not fully disposition for OSA due to hypertrophy of understood. Several factors may place infants the lymphoid tissues has been suggested, since and children at risk for developing the OSA young black subjects have more lymphoid tis- syndrome. The leading cause of sleep-related sue than young white subjects.72 increases in upper airway resistive load in the Of the craniofacial abnormalities that have paediatric population is the prominence of been found to be responsible for sleep-related lymphoid tissues.9"0 However, the severity of upper airways obstruction, the Pierre Robin OSA is not always proportional to the size syndrome has been extensively studied.73 Using of the tonsils and adenoids.5657 This suggests flexible fibreoptic endoscopy Sher et al showed involvement of other risk factors such as ab- that obstruction of the airways is due not only normal ventilatory drive and/or mechanical and to glossoptosis but also to many other ab- anatomical abnormalities of the upper airways. normalities.74 In infants with micrognathia the Few studies have evaluated ventilatory drive pharyngeal airway closing pressure during nasal in children with OSA. One early study found occlusion trials was correlated with genio- http://thorax.bmj.com/ that some children had low hypercapnic ventil- glossus muscle activity, suggesting that this atory responses when awake several years after muscle contributes to pharyngeal airway pat- adenotonsillectomy.58 However, Marcus et al ency in micrognathic infants.75 recently reported normal hypercapnic ventil- Endoscopic observations in children with the atory responses when awake in children with OSA syndrome due to other craniofacial an- tonsilloadenoidal hypertrophy.59 The ventil- omalies such as Crouzon syndrome, Treacher- atory response to chemical stimuli during sleep Collins syndrome, and other disorders have has not been studied. It can be speculated shown that the mechanism of airway collapse that the sleep-related decrease in ventilatory is variable.76 The midfacial and mandibular on September 28, 2021 by guest. Protected copyright. responses to chemical stimuli may differ be- hypoplasia and glossoptosis seen in Down's tween healthy children and children with syndrome increase the risk of OSA. Un- chronic upper airways obstruction. On the diagnosed OSA may contribute to the un- other hand, children with OSA appear to have explained seen in normal central control of the upper airway some of these children.77 muscles during sleep. Continuous upper airway Other disorders associated with an increased muscle activity was found during airway ob- risk of OSA in children include sickle cell an- struction, and this muscle activity increased aemia,78 brainstem disorders such as Arnold- with the degree of hypercapnia and hyp- Chiari malformation79 and myelomeningo- oxaemia.60 Furthermore, a decrease in genio- cele,7980 achondroplasia,8' neuromuscular dis- glossus muscle activity at the onset of ob- orders,82 and Prader Willi syndrome.83 In infants structive apnoeas has been found in adults6' laryngomalacia can be responsible for but not in children.62 In children, obstructive severe OSA.84 apnoeas may, rather, be the result of a sudden increase in upper airways resistance. Fibro- scopic6" and fluoroscopic64 studies in children with enlarged tonsils have shown that in- Familial factors spiratory movements of the tonsils and pharyn- A familial basis for the OSA syndrome is sug- geal walls tend to narrow the upper airways gested by reports of families with several affec- and occasionally lead to occlusion. A narrow ted members.8485 One recent pilot study airway is an additional risk factor. A relationship showed an increased frequency of sleep-dis- has been reported between the size of the pos- ordered breathing in relatives of non-obese terior airway and the severity of the OSA adult patients with sleep apnoea/hyponoea syn- syndrome.57 65 A recent study evaluated the drome.86 Preliminary data on the prevalence of mechanical properties of the in chil- snoring in the parents of children who snore 1208 Gaultier have been reported.87 Ventilatory control dys- and children. Further investigations and multi- function and craniofacial morphology ab- centre studies are needed to their clinical

clarify Thorax: first published as 10.1136/thx.50.11.1204 on 1 November 1995. Downloaded from normalities have a familial basis85 and may be usefulness for elucidating the pathophysiology risk factors for OSA in adults. Guilleminault of OSA and for determining the best treatment et al reported five families in which several strategy. members, covering three generations, had OSA Tonsillectomy and adenoidectomy have been associated with a small upper airway.88 Thus, the most commonly recommended treatments. there is evidence that familial factors influence However, associated problems such as an ab- the risk of developing an increase in upper normally long soft palate, retroposition of the airway resistive loads. Adult physicians and mandible, or soft tissue infiltration behind the paediatricians should look for symptoms of base ofthe tongue must receive attention. Such sleep-disordered breathing in the relatives of problems may lead to residual symptoms after their patients. tonsillectomy. Long term monitoring is re- quired in infants and children treated for sleep- related upper airway symptoms. Follow up OSA and sudden infant death syndrome evaluations should include a physical ex- (SIDS) amination, detailed questionnaires, and It is unclear whether the risk factors for SIDS polysomnographic recordings if necessary. and OSA operate similarly, but there is some Symptoms sometimes recur after puberty, espe- evidence that SIDS and OSA aggregate within cially in boys.7' The usefulness of orthodontic the same families. Guilleminault et al88 observed treatment in children with mandibular ab- clinical symptoms of OSA and abnormal num- normalities after tonsillectomy is still under bers of obstructive apnoeas among the parents investigation. or grandparents of SIDS or near-miss SIDS In 1986 Guilleminault suggested that nasal cases in five families. The risk was apparently continuous positive airway pressure (CPAP) related to the presence of a small posterior could be used as an alternative to tracheostomy airway, which was found in several family mem- in young patients with OSA due to craniofacial bers including children. Infants with near-miss abnormalities.97 The preliminary findings of a SIDS were followed up and found to develop multicentre study conducted in North America OSA during childhood.8990 These are the first and France have recently been reported.9899 patients who have been studied during the The patients were obese or had craniofacial development of OSA. More recently the same abnormalities or residual problems after ton- group found sleep-related increases in upper sillectomy.1'0 The mean level of positive pres- airways resistance in infants with a family his- sure used was lower than in adults with OSA. tory of SIDS, apparent life-threatening events, However, pressure requirements changed with and parental sleep-related breathing dis- growth, suggesting that CPAP requirements http://thorax.bmj.com/ orders.54 These infants may be at the highest should be routinely re-evaluated at regular in- end ofthe spectrum ofat risk infants. However, tervals. In general, the level of pressure was set these findings are in agreement with those of to maintain the Sao2 above 95%. However, a Belgian case control study that found a sig- further investigations are needed to establish nificant increase in the rate of occurrence of the best criteria for selecting the optimal pres- obstructive events in infants who later died of sure. In infants with sleep-related increases in SIDS compared with control infants.9' In two upper Guilleminault re- ongoing studies of the familial aggregation of commended that the level of nasal

pressure on September 28, 2021 by guest. Protected copyright. OSA, families with both OSA in adults and should be selected to maintain the oesophageal SIDS ornear-miss SIDShave been identified.85 92 pressure no lower than -8 cm H20 during All these data suggest that there is a subset of sleep.54 Commercial masks for infants are avail- families at risk for both disorders. From a able, but in patients with craniofacial ab- clinical point of view, paediatricians and adult normalities custom-made masks may be physicians should look for familial histories of necessary. Finally, the BiPAP system may be both disorders and should recommend a careful useful in some cases. Further studies are needed investigation in at risk infants. to determine the specific indications of both CPAP and the BiPAP system. In patients with craniofacial abnormalities Treatment treatment with CPAP enables the patient to The optimal treatment strategies for paediatric wait until optimal surgery can be performed OSA are still the focus of intensive research, and avoids the use of a tracheostomy in young taking into account not only obstructive patients. Close follow up is mandatory. In apnoeas but also sleep-related increases in patients with the Pierre Robin syndrome some upper airways resistive load. Treatment should studies have found that clinical and poly- be considered only after objective testing to somnographic abnormalities persisted during determine the severity of the syndrome and childhood and adolescence.9610' Finally, after otorhinolaryngological and maxillofacial laryngomalacia can be treated successfully by studies. The pretreatment examination should epiglottoplasty.84 include radiological evaluation,9394 cephalo- metric measurements,95 fluoroscopic and fibroscopic studies,63 6496 computed tomo- Summary graphic scanning and magnetic resonance The presence of increased upper airway res- imaging.70 The respective indications of these istive loads during sleep can now be diagnosed procedures are not yet standardised in infants by paediatricians. However, diagnostic criteria Obstructive sleep apnoea syndrome in infants and children 1209 21 MesserJ. Mort subite par apnees obstructives chez l'enfant. need to be further clarified to allow accurate Arch Fr Pediatr 1984;41:333-6. identification of episodes of partial airway ob- 22 Wilkinson AR, McCormick MS, Freeland AP, Pickering

D. Electrocardiographic signs of pulmonary hypertension Thorax: first published as 10.1136/thx.50.11.1204 on 1 November 1995. Downloaded from struction. New technological advances can be in children who snore. BMJ7 1981;282:1579-81. expected to help to determine the clinical use- 23 Hunt CE, Brouillette RT. Abnormalities of breathing con- trol and airway maintenance in infants and children as a fulness of ambulatory testing during sleep and cause of cor pulmonale. Pediatr Cardiol 1982;3:249-56. thus to establish the indications for poly- 24 Tal A, Leiberman A, Margulis G, Sofer S. Ventricular dysfunction in children with obstructive sleep : somnographic investigations in the laboratory. radionuclide assessment. Pediatr Pulmonol 1988;4:139- A thorough investigation of the anatomical ab- 43. 25 Guilleminault C, Shiomi T, Stoohs R, Schnittger I. Echo- normalities that contribute to airways ob- cardiographic studies in adults and children presenting struction is essential for selecting the most with obstructive or heavy snoring. In: Gaultier C, Escourrou P, Curzi-Dascalova L, eds. Sleep and cardio- appropriate therapy. However, the order in respiratory control. Colloque INSERM/John Libbey which these investigations should be performed Eurotext Ltd, 1991:95-103. 26 Wadowski SJ, Shatila AF, Singh S, Rao M. Failure of remains unclear. The diagnostic tools, in- history, physical, laboratory or nap studies to predict cluding questionnaires and sleep testing, and pulmonary hypertension in children with . Am J Respir Crit Care Med 1994;149:A885. methods aimed at investigating patho- 27 Kunzman LA, Keens TG, Davidson Ward SL. Incidence physiological mechanisms should be stand- ofsystemic hypertension in children with obstructive sleep apnea syndrome. Am Rev Respir Dis 1991;141:A808. ardised for multicentre studies. Familial factors 28 D'Andrea LA, Rosen CL, Haddad GG. Severe should be taken into acount. The best strategy in children with upper airway obstruction during sleep does not lead to significant changes in heart rate. Pediatr for preventing the complications of the OSA Pulmonol 1993;16:362-9. syndrome is to identify the disorder as early 29 Guilleminault C, Connolly S, Winkle R, Melvin K, Tilkian A. Cyclical variation ofheart rate in sleep apnea syndrome. as possible. This requires close cooperation Mechanisms and usefulness of 24th electrocardiography between adult physicians and paediatricians as a screening technique. Lancet 1984;i: 126-31. 30 Baharav A, Kotagal S, Rubin BK, Gibbons V, Pratt J, called upon to evaluate sleep-related disorders. Karim J, et al. Obstructive sleep apnea and the autonomic cardiovascular control: an investigation by power spec- 1 Guilleminault C, Eldridge F, Simmons F, Dement WC. trum analysis of heart rate variability. Am J Respir Crit Sleep apnea in eight children. Pediatrics 1976;58:23-31. Care Med 1994;149:A558. 2 Guilleminault C, Winkle R, Korobkin R, Simmons B. 31 Brouillette R, Hanson D, David R, Klemka L, Szatkowski Children and nocturnal snoring: evaluation of the effects A, Ferbach S, et al. A diagnostic approach to children of sleep related respiratory resistive load and day time with suspected obstructive sleep apnea. J Pediatr 1984; functioning. Eur Pediatr 1982;139:165-71. 105:10-14. 3 Rosen CL, D'Andrea L, Haddad GG. Adult criteria for 32 Carroll JL, McColley SA, Marcus CL, Curtis S, Pyzik P, obstructive sleep apnea do not identify children with Loughlin GM. Reported symptoms of childhood ob- serious obstruction. Am Rev Respir Dis 1992;146:1231-4. structive sleep apnea syndrome vs primary snoring. Am 4 Carroll JL, Loughlin GM. Diagnosis criteria for obstructive Rev Respir Dis 1992;145:A177. sleep apnea syndrome in children. Pediatr Pulmonol 1992; 33 Kahn A, Groswasser J, Sottiaux M, Rebuffat E, Sunseri 14:71-4. M, Franco P, et al. Clinical symptoms associated with 5 Jeans WD, Fernando DC, Maw AR, Leighton BC. A brief obstructive sleep apnea in normal infants. Sleep longitudinal study of the growth of the nasopharynx and 1993;16:409-13.

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