BEST PRACTICE SLEEP APNOEA. Robert Primhak, Christopher O Brien. ep87

See end of artile for authors affiliations Correspondene to: Dr Robert Primhak, Sheffield Children s Hospital, Western Bank, Sheffield, S10 2TH, UK; r.a.primhak@sheffield.a.uk I BEST PRACTICE SLEEP APNOEA Robert Primhak, Christopher O Brien Arh Dis Child Edu Prat Ed 2005; 90:ep87 ep91. doi: 10.1136/ad.2005.072975 n reent years there has been a dramati inrease in the reognition of sleep related breathing disorders in hildren, and a onsequent but less dramati inrease in the availability of speialist provision for the diagnosis and treatment of suh problems. However, the linial awareness of these problems and their possible onsequenes remains pathy. The purpose of this artile is to review the auses and onsequenes of sleep apnoea in hildren, to guide liniians in the reognition of those hildren who need assessment, and to outline the management options. Sleep apnoea in hildren may inlude obstrutive sleep apnoea or hypopnoea and sleep apnoea or hypoventilation due to entral auses. By far the most ommon of these pathologies is obstrutive sleep apnoea. Obstrutive sleep apnoea has been defined as a disorder of breathing during sleep haraterised by prolonged partial upper airway obstrution and/or intermittent omplete obstrution that disrupts normal ventilation during sleep and normal sleep patterns. 1 In this artile we will onentrate on obstrutive airway problems leading to sleep apnoea, although high risk groups with mixed pathology will be disussed. We will not deal with purely entral auses of sleep apnoea or hypoventilation, suh as ongenital entral hypoventilation syndrome, nor with apnoea or apparently life threatening events of infany. AETIOLOGY Apnoea or pathologial hypoventilation during sleep may result from a derease in entral drive, a redution in musle power, or most ommonly from upper airway obstrution. The newborn infant spends 16 18 hours of the day asleep, and the majority of this is rapid eye movement (REM) sleep. The pharyngeal airway is maintained by mental and submental musles suh as genioglossus, and these relax during sleep, failitating upper airway ollapse. During REM sleep these effets are most pronouned, and interostal musles are also relaxed, leading to a reliane on diaphragmati breathing and paradoxial inward movement of the hest wall during inspiration. Other onsequenes of REM sleep are a redued and less stable funtional residual apaity, redued minute ventilation, and an inreased hypoxi arousal threshold. The stage is therefore set for airway and breathing problems during sleep, whih are likely to be partiularly severe in REM sleep. 2 Although airway obstrution is exaerbated by musle tone hanges during sleep, there are usually underlying anatomial fators whih predispose to the problem in the first plae. These may inlude raniofaial abnormalities, obesity, and adenotonsillar hypertrophy. The presene of neuromusular disease inreases the risk of sleep related breathing disorders inluding sleep apnoea. Underlying onditions whih predispose to obstrutive sleep apnoea are listed in table 1. Often airway obstrutions our in series, when the inreased inspiratory pressure required at eah obstrution will enhane the degree of ollapse at more proximal narrowings, so that the effets of several obstrutions in series may be greater than the sum of their parts. There is evidene that obstrutive sleep apnoea and infant apnoeas have ommon familial fators, whih may be related to both upper airway anatomy and to ontrol of musle tone and breathing during sleep. 3 It has therefore been hypothesised that hildren with obstrutive sleep apnoea are at higher risk of similar reurrent problems later in life. Two problems make identifiation of the problem more diffiult. Firstly, some hildren may have gas exhange abnormalities during sleep without frank obstrutive sleep apnoea, but with a pattern of obstrutive hypoventilation. Seondly some hildren will have symptoms from upper airway obstrution that are not assoiated with demonstrable gas exhange abnormalities but are aused by frequent arousals and fragmentation of sleep. Both are more diffiult to demonstrate or haraterise on physiologial monitoring. EPIDEMIOLOGY One of the major hallenges in delineating sleep related breathing disorders (SRBD) is the definition of abnormality. Normal referene values for apnoea in hildhood have been published, and differ from those used in adults. 4 From these data we an state that it is abnormal for a hild over the age of 1 year to have obstrutive apnoea lasting longer than 10 seonds, or to desaturate ep87 Arh Dis Child Edu Prat Ed: first published as 10.1136/ad.2005.072975 on 21 November 2005. Downloaded from http://ep.bmj.om/ on 25 September 2018 by guest. Proteted by opyright. www.arhdishild.om

ep88 Table 1 Causes of obstrutive sleep apnoea Adenotonsillar hypertrophy Obesity Down syndrome* Craniofaial abnormalities* - poorly formed jaw (e.g. Pierre Robin sequene, Treaher Collins syndrome) - midfaial hypoplasia (e.g. Apert syndrome, Crouzon syndrome) Ahondroplasia Muopolysaharidoses Prader-Willi syndrome Neuromusular disease* Cerebral palsy *Obstrution may evolve in very early infany. below 90% during sleep. On the other hand, obstrutive apnoeas our to a greater or lesser extent in 18% of normal hildren and we do not know the exat ut off whih predits pathologial onsequenes. Various authors have doumented obstrutive sleep apnoea ausing gas exhange abnormalities to our in 0.7 2.9% of pre-pubertal hildren. 5 7 Habitual snoring ours in 12% of 4 5 year old hildren in the UK 5 and in 10% of 8 10 year old German hildren. 8 Reent studies have suggested that snoring in primary shool hildren is a preditor of later aademi performane. 9 Although abnormal gas exhange has usually been taken to indiate a signifiant abnormality, a large population based survey indiated that snoring is a better preditor than noturnal hypoxaemia for poor aademi performane. 8 We do not yet know whih physiologial abnormalities are the best preditors of a good response to treatment. In high risk hildren the risk of sleep apnoea or other sleep related breathing disorders is muh higher and warrants routine evaluation even in the absene of obvious symptoms, sine snoring and poor performane are ommon in many of the onditions listed. CONSEQUENCES AND COMPLICATIONS As disussed above, there is onsiderable evidene that sleep apnoea is assoiated with worse aademi performane, onentration, and behaviour. This may be due to sleep fragmentation, and although intervention may improve behaviour and onentration, effets on performane may be seen long after the symptoms have disappeared. Other onsequenes of sleep apnoea inlude failure to thrive, systemi hypertension with inreased left ventriular mass, or pulmonale, and pulmonary oedema. All of these ompliations reverse when the underlying problem is treated. Pulmonary hypertension may rarely ompliate sleep apnoea in hildren, and may be irreversible. There are oasional reports of oma and death resulting from undiagnosed obstrutive sleep apnoea, though this is an extremely rare ompliation. Children with obstrutive sleep apnoea have inreased health are utilisation even after allowing for the diret management of the sleep apnoea, suggesting that it may at as an amplifier of other health problems. IDENTIFICATION, ASSESSMENT, AND DIFFERENTIAL DIAGNOSIS Exessive daytime sleepiness is less ommon in hildren with SRBD than it is in adults. In hildren without underlying disorders, the presene of noturnal obstrutive symptoms is Table 2 Symptoms and signs seen more ommonly in obstrutive sleep apnoea Night time Snoring and snorting Gasps or witnessed apnoeas Restlessness and unusual sleep postures (e.g. extended nek) Laboured breathing Early morning headahe Exessive sweating Enuresis Daytime Irritability, behavioural problems Poor onentration Failure to thrive Upper airway obstrution/mouth breathing Harrison s suli usual if obstrutive sleep apnoea is present. However, symptoms have poor speifiity, and many hildren with symptoms will not have polysomnographi abnormalities. Symptoms and signs whih our more ommonly in obstrutive sleep apnoea are listed in table 2. In hildren with suggestive symptoms, further physiologial assessment may be indiated. A number of end points an be measured, as desribed below. Oxygenation The simplest assessment method is overnight pulse oximetry. This an be done in the home, ensuring a more typial night s sleep ompared to a hospital study. Several pulse oximeters now have storage and analysis software available to enable quantifiation of hypoxaemi dips. Dips in saturation of. 4% from baseline and falls below 90% saturation an be quantified and ompared to normal values. 10 Abnormal oximetry is speifi for SRBD, but normal oximetry does not exlude sleep apnoea on polysomnography. Figure 1 shows oximetry reordings on a 2 year old hild with failure to thrive from obstrutive sleep apnoea. Note the normalisation of oximetry after adenotonsilletomy, and the lower heart rate during sleep. Respiratory events A more detailed method of assessment is limited polysomnography, measuring heart rate, respiratory effort, and airflow and movement as well as oximetry and a measure of arterial pco 2. This an give a more detailed estimate of impaired gas exhange, and differentiate between entral and obstrutive events. This sort of ardiorespiratory assessment is imperative if the linial problem is not a straightforward obstrutive sleep apnoea requiring adenotonsilletomy, but it does not help in the assessment of eletroenephalogram (EEG) arousals without impairment of gas exhange. Arousals assoiated with signifiant movement an, however, be seen. It has the advantage that it is relatively easy to set up, is not expensive, and has more potential to be performed in the hild s home. Arousals More detailed polysomnography inludes limited EEG, eletro-oulogram, and submental eletromyogram to allow sleep staging and a measure of neurologial arousals resulting from respiratory events, but this is tehnially demanding to set up and sore, and there are relatively few Arh Dis Child Edu Prat Ed: first published as 10.1136/ad.2005.072975 on 21 November 2005. Downloaded from http://ep.bmj.om/ on 25 September 2018 by guest. Proteted by opyright. www.arhdishild.om

Saturation (%) Saturation (%) A 100 95 90 85 80 75 70 22:00 24:00 02:00 04:00 06:00 08:00 Time (hours) B 100 95 90 85 22:00 24:00 02:00 04:00 06:00 Time (hours) Figure 1 Oximetry reordings on a 2 year old boy with failure to thrive aused by obstrutive sleep apnoea. (A) before adenotonsilletomy. (B) Two weeks after surgery. paediatri failities in the UK whih offer this investigation. Behavioural arousals an be estimated from movement and video. Reently the pulse transit time (PTT) has been used to assess arousals. PTT is the time between the QRS omplex on the eletroardiogram (ECG) and the peak of the plethysmographi waveform on the pulse oximeter, and is inversely related to peripheral vasomotor tone. A fall in PTT an be used as a measure of autonomi arousal and may be even more sensitive than the EEG arousal at deteting obstrutive events. 11 High risk hildren In high risk hildren some form of regular sreening for sleep apnoea is imperative. Almost all hildren with Down syndrome have a degree of sleep related breathing disorder, 12 and these hildren are at partiular risk of pulmonary hypertension even with trivial ardia lesions, so every effort should be made to prevent noturnal hypoxaemia. Children with Down syndrome or raniofaial problems should have some assessment of gas exhange during sleep in infany and thereafter at least every 6 12 months until the age of maximum adenotonsillar growth at 5 7 years. Children with Duhenne musular dystrophy are at partiular risk of sleep related breathing problems, espeially when they beome wheelhair dependent, and they should have assessment of gas exhange (preferably inluding apnography) from this age onwards on at least a yearly basis. Other neuromusular onditions may also lead to sleep hypoventilation, espeially if there is diaphragmati involvement, and liniians should have a low threshold for investigation. MANAGEMENT Sleep apnoea without an underlying ondition In nearly all ases this will be due to adenotonsillar hypertrophy. The presene of noturnal hypoxaemia or of ompliations suh as failure to thrive, ardia effets, or hest deformity mandate urgent treatment in the form of adenotonsilletomy. Adenotonsillar size alone is not a good indiator of obstrution or the response to surgery. It is important that both tonsils and adenoids are removed, as adenoidetomy alone or adenomonotonsilletomy are assoiated with a higher failure rate. 13 In hildren with signifiant hypoxaemia at night there is an inreased risk of perioperative ompliations, 14 and overnight oximetry should be performed as a preoperative sreen to identify these high risk hildren. A deision pathway is shown in fig 2. Nasal steroids have been used as a short term measure to improve overnight airway pateny in adenotonsillar hypertrophy, 15 but there are no studies of their long term effiay. Oral jaw positioning devies have been shown to improve airway obstrution in hildren with malolusion 16 but are not widely used in the UK. In hildren with symptoms suggesting sleep apnoea but with normal oximetry the issues are muh less straightforward. On the one hand there may be sleep fragmentation with impats on learning and behaviour as well as growth, but on the other hand it is learly undesirable to subjet a hild to unneessary adenotonsilletomy when the problem may be self limiting. More detailed assessment of the frequeny of arousals and severity of sleep related breathing disorder is indiated in these ases using either limited or full polysomnography, but it should be reiterated that we do not yet have good evidene about whih abnormalities predit a good outome from intervention. If sleep apnoea persists despite surgial treatment, full polysomnography should be undertaken in a speialist entre. This situation is unusual, and we onsider that it warrants detailed evaluation before ommitting a hild to further intervention. Nasal ontinuous positive airway pressure (CPAP) or bi-level positive airway pressure (BIPAP) ventilation at night may be neessary. Sleep apnoea with an underlying ondition In most ases of upper airway obstrution aused by an underlying ondition, adenotonsilletomy should still be onsidered as first hoie treatment, but it is less reliably effetive. Down syndrome disturbs breathing during sleep for several reasons. The low musle tone predisposes to upper airway ollapse; a large tongue tends to impede the oropharyngeal airway; midfaial hypoplasia redues the nasal airway diameter; and the reurrent upper respiratory infetions further impede nasal airway pateny. To ompound matters these hildren often have inreased pulmonary blood flow beause of ongenital heart disease and are at partiular risk of pulmonary hypertension. 17 In hildren with Down syndrome who do not respond to adenotonsilletomy, raniofaial or tongue surgery may be onsidered. Nasal CPAP is helpful in these ases, but may be diffiult to ahieve in pratie. If there is onern about hypoxaemia leading to pulmonary hypertension then supplemental oxygen at night may be an effetive palliative measure, although it does not orret the underlying problem. Oxygen supplementation may ause worse sleep apnoea in some hildren and should only be used if polysomnography shows that it does not affet breathing ontrol. 18 Children with obesity and sleep apnoea persisting after adenotonsilletomy often need nasal CPAP or BIPAP, as weight redution an rarely be ahieved in the time sale needed. The management of obstrutive sleep apnoea in raniofaial problems is ideally the orretion of the raniofaial ep89 Arh Dis Child Edu Prat Ed: first published as 10.1136/ad.2005.072975 on 21 November 2005. Downloaded from http://ep.bmj.om/ on 25 September 2018 by guest. Proteted by opyright. www.arhdishild.om

ep90 Figure 2 Deision pathway for the assessment of a hild presenting with snoring, with no underlying high risk ondition. problem. In hildren with Pierre Robin sequene the plaement of a nasopharyngeal airway an avoid traheostomy and enable safe home management until the airway grows suffiiently. 19 In other raniofaial problems, if orretive surgery is not immediately possible then adenotonsilletomy is still helpful. Nasal CPAP remains an option, but is less effetive, and traheostomy may be neessary until orretion an be ahieved. One of the most problemati groups of hildren with sleep related breathing disorders are those with erebral palsy. Poor midfaial growth oupled with abnormal airway tone and bulbar dysfuntion an lead to obstrution whih is diffiult to treat. Oral jaw positioning devies may have a role in this group. If adenotonsilletomy is ineffetive then more aggressive treatment an pose both linial and ethial problems. Children with neuromusular disease who have sleep related breathing disorders will almost always require overnight BIPAP. This has been shown to improve life expetany dramatially in Duhenne musular dystrophy in the presene of respiratory failure, 20 21 and is generally very well tolerated. It should be remembered that overnight respiratory support is only part of a pakage of interventions needed to Sleep apnoea: key points Sleep apnoea and hypoventilation problems are ommon in hildhood, with 10 12% of hildren habitually snoring and 0.7 2.9% showing signifiant gas exhange abnormalities Consequenes of sleep apnoea inlude learning and behaviour problems, failure to thrive and life threatening ardiorespiratory effets The presene of symptoms is sensitive but not speifi as an indiator of physiologial derangement Overnight oximetry is speifi but not sensitive as an indiator of physiologial derangement Adenotonsilletomy is the first line treatment of obstrutive sleep apnoea and is usually urative in unompliated disease Overnight oximetry should be performed in any hild where adenotonsilletomy is planned for obstrutive sleep apnoea Children with underlying onditions whih predispose to sleep related breathing disorders should be sreened with oximetry apnography on a regular basis If adenotonsilletomy is not effetive or feasible then other treatments inluding nasal CPAP or BIPAP should be onsidered. These will require speialist referral Arh Dis Child Edu Prat Ed: first published as 10.1136/ad.2005.072975 on 21 November 2005. Downloaded from http://ep.bmj.om/ on 25 September 2018 by guest. Proteted by opyright. www.arhdishild.om

protet the respiratory health of hildren with neuromusular disease; other measures inlude hest physiotherapy with assisted oughing, soliosis orretion, and prevention of reflux and aspiration. 22 GUIDELINES, EVIDENCE, AND FUTURE RESEARCH The Amerian Aademy of Pediatris has produed a linial pratie guideline and tehnial report on the diagnosis and management of hildhood obstrutive sleep apnoea. 23 24 These guidelines are based on a systemati approah to the literature and formal grading of evidene. They have an emphasis on the gold standard of polysomnography in the diagnosis of obstrutive sleep apnoea, whih is somewhat tautologial, sine by definition the ondition requires polysomnography to quantify it. A Cohrane review of the role of adenotonsilletomy in obstrutive sleep apnoea in hildren onluded that there were no aeptable randomised ontrolled trials supporting this intervention. 25 There are, however, a large number of observations of dramati physiologial and linial improvement after intervention. The key question whih remains unanswered is what degree and what type of physiologial derangement is linially important, and suffiient to warrant intervention. CONTENTIOUS ISSUES In addition to the major issue of not knowing what level or type of physiologial derangement is an indiation for intervention (disussed above), there are other ontentious issues in this field. Assessment of arousals There are several methods of assessing arousals, desribed above. It is unlear whih of these will be the best preditor of response to treatment. When is a full polysomnography indiated? The advantages of a full polysomnogram, inluding neurophysiologial measures, is that it an be used to assess sleep arhiteture, inluding arousals and presene or absene of REM sleep. Sine sleep apnoea may our only during REM, this may be important in interpreting a negative study. If a hild is referred beause of daytime sleepiness or other symptoms thought to be onsequent of sleep deprivation, then the sleep arhiteture may add useful information, partiularly if no major breathing problem is found. On the other hand, it is expensive of resoures, limited in availability, and muh less physiologial than a home study of limited ardiorespiratory parameters. Sine the majority of questions an be answered with limited studies, we would reommend that full polysomnography is reserved for hildren with atypial symptoms, where there is ontinuing unertainty after simple testing, or where initial surgial treatment of presumed obstrutive sleep apnoea has been ineffetive. RECOMMENDED READING Amerian Aademy of Pediatris. Clinial pratie guideline: diagnosis and management of hildhood obstrutive sleep apnea syndrome. Pediatris 2002;109:704 12. Amerian Thorai Soiety. Standards and indiations for ardiopulmonary sleep studies in hildren. Am J Respir Crit Care Med 1996;153:866 78.... Authors affiliations R Primhak, Sheffield Children s Hospital, Western Bank, Sheffield, UK C O Brien, Royal Vitoria Infirmary, Newastle, UK Competing Interests: Both authors are members of the Royal College of Paediatris and Child Health working party into sleep physiology and respiratory ontrol disorders in hildhood. REFERENCES 1 Amerian Thorai Soiety. Standards and indiations for ardiopulmonary sleep studies in hildren. Am J Respir Crit Care Med 1996;153:866 78. 2 Gaultier C. Cardiorespiratory adaptation during sleep in infants and hildren. Pediatr Pulmon 1995;19:105 17. 3 MNamara F, Sullivan C. The genesis of adult sleep apnea in hildhood. 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Neuromusular Disorders 2002;12:926 9. 22 Wallgren-Pettersson C, Bushby K, Mellies U, et al. 117th ENMC workshop: ventilatory support in ongenital neuromusular disorders ongenital myopathies, ongenital musular dystrophies, ongenital myotoni dystrophy and SMA (II) 4 6 April 2003, Naarden, The Netherlands. Neuromusular Disorders 2004;14:56 69. 23 Amerian Aademy of Pediatris. Clinial pratie guideline: diagnosis and management of hildhood obstrutive sleep apnea syndrome. Pediatris 2002;109:704 12. 24 Shehter MS. Tehnial report: diagnosis and management of hildhood obstrutive sleep apnea syndrome. Pediatris 2002;109:e69. 25 Lim J, MKean M. Adenotonsilletomy for obstrutive sleep apnoea in hildren. Cohrane Database of Systemati Reviews 2004;1. ep91 Arh Dis Child Edu Prat Ed: first published as 10.1136/ad.2005.072975 on 21 November 2005. Downloaded from http://ep.bmj.om/ on 25 September 2018 by guest. Proteted by opyright. www.arhdishild.om