title: Lateral sleeping position reduces severity of central sleep apnea / Cheyne-Stokes respiration.
abstract: BACKGROUND
  The influence of sleeping position on obstructive sleep apnea severity is well established. However, in central sleep apnea with Cheyne Stokes respiration (CSA-CSR) in which respiratory-control instability plays a major pathophysiologic role, the effect of position is less clear.
  
  
  OBJECTIVE
  To examine the influence of position on CSA-CSR severity as well as central and mixed apnea frequency.
  
  
  METHODS
  Polysomnograms with digitized video surveillance of 20 consecutive patients with heart failure and CSA-CSR were analyzed for total apnea-hypopnea index, mean event duration, and mean oxygen desaturation according to sleep stage and position. Position effects on mixed and central apnea index, mean apnea duration, and mean desaturation were also examined in non-rapid eye movement sleep.
  
  
  RESULTS
  Data are presented as mean +/- SEM unless otherwise indicated. Group age was 59.9 +/- 2.3 years, and total apnea-hypopnea index was 26.4 +/- 3.0 events per hour. Compared with supine position, lateral position reduced the apnea-hypopnea index in all sleep stages (Stage 1, 54.7 +/- 4.2 events per hour vs 27.2 +/- 4.1 events per hour [p < .001]; Stage 2, 43.3 +/- 6.1 events per hour vs 14.4 +/- 3.6 events per hour [p < .001]; slow-wave sleep, 15.9 +/- 6.4 events per hour vs 5.4 +/- 2.9 events per hour [p < .01]; rapid eye movement sleep, 38.0 +/- 7.3 events per hour vs 11.0 +/- 3.0 events per hour [p < .001]). Lateral position attenuated apnea and hypopnea associated desaturation (supine 4.7% +/- 0.3%, lateral 3.0% +/- 0.4%; p < .001) with no difference in event duration (supine 25.7 +/- 2.8 seconds, lateral 26.9 +/- 3.4 seconds; p = .921). Mixed apneas were longer than central (29.1 +/- 2.1 seconds and 19.3 +/- 1.1 seconds; p < .001) and produced greater desaturation (6.1% +/- 0.5% and 4.5% +/- 0.5%, p = .003). Lateral position decreased desaturation independent of apnea type (supine 5.4% +/- 0.5%, lateral 3.9% < or = 0.4%; p = .003).
  
  
  CONCLUSIONS
  Lateral position attenuates severity of CSA-CSR. This effect is independent of postural effects on the upper airway and is likely to be due to changes in pulmonary oxygen stores. Further studies are required to investigate mechanisms involved.
authors.affiliation: Department of Allergy Immunology and Respiratory Medicine, Alfred Hospital, Melbourne, Australia.
authors.forename: Irene
authors.initials: I
authors.lastname: Szollosi
authors.forename: Teanau
authors.initials: T
authors.lastname: Roebuck
authors.forename: Bruce
authors.initials: B
authors.lastname: Thompson
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Naughton
mesh_terms: D000328:Adult; D000368:Aged; D002245:Carbon Dioxide / Q000097:blood; D002639:Cheyne-Stokes Respiration / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D005260:Female; D006333:Heart Failure / Q000150:complications; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D017286:Polysomnography; D011187:Posture / Q000502:physiology; D012125:Respiratory Center / Q000503:physiopathology; D012891:Sleep Apnea Syndromes / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D020182:Sleep Apnea, Central / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D012894:Sleep Stages / Q000502:physiology; D016683:Supine Position
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen