title: Effect of continuous positive airway pressure on sleep structure in heart failure patients with central sleep apnea.
abstract: OBJECTIVE
  At termination of obstructive apneas, arousal is a protective mechanism that facilitates restoration of upper airway patency and airflow. Treating obstructive sleep apnea (OSA) by continuous positive airway pressure (CPAP) reduces arousal frequency indicating that such arousals are caused by OSA. In heart failure (HF) patients with central sleep apnea (CSA), however, arousals frequently occur several breaths after apnea termination, and there is uncertainty as to whether arousals from sleep are a consequence of CSA. If so, they should diminish in frequency when CSA is attenuated. We therefore sought to determine whether attenuation of CSA by CPAP reduces arousal frequency.
  
  
  METHODS
  Randomized controlled clinical trial.
  
  
  METHODS
  We examined data from 205 HF patients with CSA (apnea-hypopnea index [AHI] > or =15, > 50% were central) randomized to CPAP or control who had polysomnograms performed at baseline and 3 months later.
  
  
  RESULTS
  In the control group, there was no change in AHI or frequency of arousals. In the CPAP-treated group, the AHI decreased significantly (from [mean +/- SD] 38.9 +/- 15.0 to 17.6 +/- 16.3, P < 0.001) but neither the frequency of arousals nor sleep structure changed significantly.
  
  
  CONCLUSIONS
  These data suggest that attenuation of CSA by CPAP does not reduce arousal frequency in HF patients. We conclude that arousals were not mainly a consequence of CSA, and may not have been acting as a defense mechanism to terminate apneas in the same way they do in OSA.
authors.affiliation: University of Toronto, Toronto, ON, Canada.
authors.forename: Pimon
authors.initials: P
authors.lastname: Ruttanaumpawan
authors.forename: Alexander G
authors.initials: AG
authors.lastname: Logan
authors.forename: John S
authors.initials: JS
authors.lastname: Floras
authors.forename: T Douglas
authors.initials: TD
authors.lastname: Bradley
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D045422:Continuous Positive Airway Pressure; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000150:complications*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D011446:Prospective Studies; D020182:Sleep Apnea, Central / Q000628:therapy*; D055815:Young Adult