title: Effect of body position and sleep state on obstructive sleep apnea severity in children with Down syndrome.
abstract: OBJECTIVE
  To investigate the influence of sleep position and sleep state on obstructive sleep apnea (OSA) severity in in children with Down syndrome (DS).
  
  
  METHODS
  Retrospective review.
  
  
  METHODS
  Sleep disorders laboratory of a tertiary medical center.
  
  
  METHODS
  Children with Down syndrome and typically developing children matched for age, gender, apneahypopnea index (AHI), and year of polysomnogram.
  
  
  RESULTS
  Sleep variables from baseline polysomnography. Sensor-recorded position (supine, prone, lateral) was expressed as the percentage of total sleep time. The AHI was calculated in each sleep state (NREM, REM), position, and position-sleep state combination. Of 76 DS subjects (55% male) the median age and AHI were 4.6 years (range 0.2-17.8 years) and 7.4 events/h (range 0-133). In all subjects, AHI was higher in REM than NREM (p < 0.05); however, the NREM AHI was higher in DS subjects than controls (p < 0.05). Compared to controls, the percentage of prone sleep was greater in DS subjects (p < 0.05), but the percentage of supine or non-supine (prone plus lateral) sleep was no different. For DS subjects alone, NREM AHI was higher in supine than non-supine sleep (p < 0.05).
  
  
  CONCLUSIONS
  In DS and non-DS children alike, respiratory events are predominantly REM related. However, when matched for OSA severity, children with DS have a higher NREM AHI, which is worse in the supine position, perhaps indicating a positional effect compounded by underlying hypotonia inherent to DS. These findings illustrate the clinical importance of NREM respiratory events in the DS population and implications for treatment options.
authors.affiliation: The Ritchie Centre, Monash Institute of Medical Research, Monash University, Melbourne, Victoria, Australia.
authors.forename: Lauren C
authors.initials: LC
authors.lastname: Nisbet
authors.affiliation: Comprehensive Sleep Network Inc., Seattle, WA.
authors.forename: Nicole N
authors.initials: NN
authors.lastname: Phillips
authors.affiliation: Department of Neurology, University of Michigan Sleep Disorders Centre, Ann Arbor, MI.
authors.forename: Timothy F
authors.initials: TF
authors.lastname: Hoban
authors.affiliation: Department of Neurology, University of Michigan Sleep Disorders Centre, Ann Arbor, MI ; Department of Oral and Maxillofacial Surgery, University of Michigan Sleep Disorders Center, Ann Arbor, MI.
authors.forename: Louise M
authors.initials: LM
authors.lastname: O'Brien
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004314:Down Syndrome / Q000150:complications*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D017286:Polysomnography / Q000379:methods; D011187:Posture / Q000502:physiology*; D016684:Prone Position / Q000502:physiology; D012189:Retrospective Studies; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000150:complications* / Q000503:physiopathology*; D012894:Sleep Stages / Q000502:physiology*; D012895:Sleep, REM / Q000502:physiology; D016683:Supine Position / Q000502:physiology
keywords: Down syndrome; sleep position