title: Effect of oxygen on sleep quality, cognitive function and sympathetic activity in patients with chronic heart failure and Cheyne-Stokes respiration.
abstract: BACKGROUND
  Cheyne-Stokes respiration disrupts sleep, leading to daytime somnolence and cognitive impairment. It is also an independent marker of increased mortality in heart failure. This study evaluated the effectiveness of oxygen therapy for Cheyne-Stokes respiration in heart failure.
  
  
  METHODS
  Eleven patients with stable heart failure and Cheyne-Stokes breathing were studies. Oxygen and air were administered for 4 weeks in a double-blind, cross-over study. Sleep and disordered breathing was assessed by polysomnography. Symptoms were assessed using the Epworth Sleepiness Scale, visual analogue and quality of lift scores. Cognitive function was assessed by neuropsychometric testing. Overnight urinary catecholamine excretion was used as a measure of sympathetic nerve activity.
  
  
  RESULTS
  Ninety-seven percent of apnoeas were central in origin. Oxygen therapy reduced the central apnoea rate (18.4 +/- 4.1 vs 3.8 +/- 2.1 per hour; p = 0.05) and periodic breathing time (33.6 +/- 7.4 vs 10.7 +/- 3.9% of actual sleep time; p = 0.003). Oxygen did not improve sleep quality, patient symptoms or cognitive failure. Oxygen reduced urinary noradrenaline excretion (8.3 +/- 1.5 vs 4.1 +/- 0.6 nmol.mmol-1 urinary creatinine; p = 0.03).
  
  
  CONCLUSIONS
  Oxygen stabilized sleep disordered breathing and reduced sympathetic activity in patients with heart failure and Cheyne-Stokes respiration. We were unable to demonstrate an effect on either patient symptoms or cognitive function.
authors.affiliation: Department of Cardiovascular Medicine, Queens Medical Centre, Nottingham, U.K.
authors.forename: A D
authors.initials: AD
authors.lastname: Staniforth
authors.forename: W J
authors.initials: WJ
authors.lastname: Kinnear
authors.forename: R
authors.initials: R
authors.lastname: Starling
authors.forename: D J
authors.initials: DJ
authors.lastname: Hetmanski
authors.forename: A J
authors.initials: AJ
authors.lastname: Cowley
mesh_terms: D000368:Aged; D001143:Arousal / Q000502:physiology*; D002639:Cheyne-Stokes Respiration / Q000503:physiopathology / Q000628:therapy*; D003404:Creatinine / Q000652:urine; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D006333:Heart Failure / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D009638:Norepinephrine / Q000652:urine; D010102:Oxygen Inhalation Therapy; D017286:Polysomnography; D012894:Sleep Stages / Q000502:physiology*; D013564:Sympathetic Nervous System / Q000503:physiopathology
chemical_list: D003404:Creatinine; D009638:Norepinephrine