title: Noninvasive ventilation with continuous positive airway pressure acutely improves 6-minute walk distance in chronic heart failure.
abstract: BACKGROUND
  Noninvasive ventilation with continuous positive airway pressure (CPAP) has been used in patients with chronic heart failure (CHF), although its effect on exercise tolerance in these patients is unknown. The aim of this study was to determine the effects of CPAP on exercise tolerance in outpatients with CHF.
  
  
  METHODS
  Following a double-blind, randomized, crossover, and placebo-controlled protocol, 12 patients with CHF (8 male; 4 female; age 54 +/- 12 years; body mass index 27.3 +/- 1.8 kg/m2, New York Heart Association Class II, III) underwent CPAP via nasal mask for 30 minutes in a recumbent position. Mask pressure was 3 cm H2O for 10 minutes, followed by individual progression up to 4 to 6 cm H2O, whereas placebo was fixed 0 to 1 cm H2O. A 6-minute walk test was performed after placebo and CPAP.
  
  
  RESULTS
  Continuous positive airway pressure decreased the resting heart rate (pre: 80 +/- 17 bpm; post: 71 +/- 15 bpm; P = .001) and mean arterial pressure (pre: 103 +/- 14 mm Hg; post: 97 +/- 13 mm Hg; P = .008). During exercise test, CPAP increased the distance covered (CPAP: 538 +/- 78 m; placebo: 479 +/- 83 m; P < .001) and the peak heart rate (CPAP: 98 +/- 17; placebo: 89 +/- 12 bpm; P = .049) but did not change the peak mean arterial pressure (P = .161).
  
  
  CONCLUSIONS
  Noninvasive ventilation with CPAP increased exercise tolerance in patients with stable CHF. Future clinical trials should investigate whether this effect is associated with improved clinical outcome.
authors.affiliation: Post-Graduate Program in Cardiovascular Sciences, Fluminense Federal University, Niterói, Brazil.
authors.forename: Sérgio
authors.initials: S
authors.lastname: Chermont
authors.forename: Mónica M P
authors.initials: MM
authors.lastname: Quintão
authors.forename: Evandro T
authors.initials: ET
authors.lastname: Mesquita
authors.forename: Nazareth N
authors.initials: NN
authors.lastname: Rocha
authors.forename: Antonio Claudio L
authors.initials: AC
authors.lastname: Nóbrega
mesh_terms: D015992:Body Mass Index; D045422:Continuous Positive Airway Pressure; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D006297:Health Services Accessibility; D006333:Heart Failure / Q000503:physiopathology / Q000534:rehabilitation*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D015656:Respiratory Mechanics; D013997:Time Factors; D016138:Walking