title: The effect of childhood obstructive sleep apnea on ambulatory blood pressure is modulated by the distribution of respiratory events during rapid eye movement and nonrapid eye movement sleep.
abstract: OBJECTIVE
  We aimed to investigate if different childhood obstructive sleep apnea (OSA) subtypes, namely rapid eye movement (REM)-related, nonrapid eye movement (NREM)-related and stage-independent OSA would exert different effects on ambulatory blood pressure (ABP).
  
  
  METHODS
  Data from our previous school-based cross-sectional study were reanalyzed. Subjects who had an obstructive apnea-hypopnea index (OAHI) between 1 and 10 events per hour and a total REM sleep duration of >30min were included in our analysis. REM-related and NREM-related OSA were defined as a ratio of OAHI in REM sleep (OAHIREM) to OAHI in NREM sleep (OAHINREM) of >2 and <0.5, respectively. The others were classified as stage-independent OSA.
  
  
  RESULTS
  A total of 162 subjects were included in the analysis. In the mild OSA (OAHI, 1-5events/h) subgroup, no significant differences in any ABP parameters were found between OSA subtypes. On the other hand, in subjects with moderate OSA (OAHI, 5-10events/h), the REM-related OSA subtype had a significantly lower daytime systolic blood pressure (SBP) z score (-0.13±0.90 cf 1.15±0.67; P=.012) and nighttime SBP z score (0.29±1.06 cf 1.48±0.88, P=.039) than the stage-independent OSA subtype. Linear regression analyses revealed that OAHINREM but not OAHIREM was significantly associated with both daytime (P=.008) and nighttime SBP (P=.042) after controlling for age, gender, and body size.
  
  
  CONCLUSIONS
  Children with obstructive events mainly in REM sleep may have less cardiovascular complications than those with stage-independent OSA.
authors.affiliation: Department of Pediatrics, Prince of Wales and Shatin Hospitals, The Chinese University of Hong Kong, Shatin, Hong Kong. Electronic address: junau@cuhk.edu.hk.
authors.forename: Chun Ting
authors.initials: CT
authors.lastname: Au
authors.forename: Crover Kwok Wah
authors.initials: CK
authors.lastname: Ho
authors.forename: Yun Kwok
authors.initials: YK
authors.lastname: Wing
authors.forename: Albert Martin
authors.initials: AM
authors.lastname: Li
mesh_terms: D000293:Adolescent; D001794:Blood Pressure / Q000502:physiology*; D018660:Blood Pressure Monitoring, Ambulatory; D002648:Child; D002940:Circadian Rhythm / Q000502:physiology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D015999:Multivariate Analysis; D017286:Polysomnography; D015656:Respiratory Mechanics / Q000502:physiology*; D012720:Severity of Illness Index; D012890:Sleep / Q000502:physiology*; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology*; D012895:Sleep, REM / Q000502:physiology*
keywords: Blood pressure; Children; Obstructive sleep apnea; Polysomnography; REM-related OSA; Rapid eye movement