title: Nocturnal CPAP improves walking capacity in COPD patients with obstructive sleep apnoea.
abstract: BACKGROUND
  Exercise limitation is an important issue in patients with chronic obstructive pulmonary disease (COPD), and it often co-exists with obstructive sleep apnoea (overlap syndrome). This study examined the effects of nocturnal continuous positive airway pressure (CPAP) treatment on walking capacity in COPD patients with or without obstructive sleep apnoea.
  
  
  METHODS
  Forty-four stable moderate-to-severe COPD patients were recruited and completed this study. They all underwent polysomnography, CPAP titration, accommodation, and treatment with adequate pressure. The incremental shuttle walking test was used to measure walking capacity at baseline and after two nights of CPAP treatment. Urinary catecholamine and heart rate variability were measured before and after CPAP treatment.
  
  
  RESULTS
  After two nights of CPAP treatment, the apnoea-hypopnoea index and oxygen desaturation index significantly improved in both overlap syndrome and COPD patients, however these changes were significantly greater in the overlap syndrome than in the COPD group. Sleep architecture and autonomic dysfunction significantly improved in the overlap syndrome group but not in the COPD group. CPAP treatment was associated with an increased walking capacity from baseline from 226.4 ± 95.3 m to 288.6 ± 94.6 m (P < 0.05), and decreased urinary catecholamine levels, pre-exercise heart rate, oxygenation, and Borg scale in the overlap syndrome group. An improvement in the apnoea-hypopnoea index was an independent factor associated with the increase in walking distance (r = 0.564).
  
  
  CONCLUSIONS
  Nocturnal CPAP may improve walking capacity in COPD patients with overlap syndrome.
  
  
  BACKGROUND
  NCT00914264.
authors.forename: Tsai-Yu
authors.initials: TY
authors.lastname: Wang
authors.forename: Yu-Lun
authors.initials: YL
authors.lastname: Lo
authors.forename: Kang-Yun
authors.initials: KY
authors.lastname: Lee
authors.forename: Wen-Te
authors.initials: WT
authors.lastname: Liu
authors.forename: Shu-Min
authors.initials: SM
authors.lastname: Lin
authors.forename: Ting-Yu
authors.initials: TY
authors.lastname: Lin
authors.forename: Yung-Lun
authors.initials: YL
authors.lastname: Ni
authors.forename: Chao-Yung
authors.initials: CY
authors.lastname: Wang
authors.forename: Shu-Chuan
authors.initials: SC
authors.lastname: Ho
authors.forename: Han-Pin
authors.initials: HP
authors.lastname: Kuo
mesh_terms: D000368:Aged; D002395:Catecholamines / Q000652:urine; D045422:Continuous Positive Airway Pressure; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000503:physiopathology* / Q000628:therapy*; D012129:Respiratory Function Tests; D020181:Sleep Apnea, Obstructive / Q000150:complications / Q000503:physiopathology* / Q000628:therapy*; D016138:Walking
chemical_list: D002395:Catecholamines