title: Walking exercise response to bronchodilation in mild COPD: a randomized trial.
abstract: BACKGROUND
  Patients with mild chronic obstructive pulmonary disease (COPD) present abnormal ventilatory mechanics during exercise and may require bronchodilator therapy. However, bronchodilation does not enhance cycling exercise tolerance in these patients whereas walking may be more sensitive to the effects of bronchodilation.
  
  
  OBJECTIVE
  To characterize the impact of bronchodilation on i) exercise tolerance ii) cardiopulmonary response and iii) dynamic hyperinflation following an endurance shuttle walking test in patients with mild COPD.
  
  
  METHODS
  In a randomized double-blind cross-over trial, 37 patients with GOLD stage I COPD (FEV(1), 96 ± 2% predicted, mean ± SEM) completed an endurance shuttle walking test up to exhaustion 90 ± 15 min following nebulization of a placebo [NaCl] or of ipratropium bromide/salbutamol sulfate (500 μg/2.5 mg) combination.
  
  
  RESULTS
  FEV(1) significantly increased following bronchodilation compared with placebo (0.17 ± 0.02 vs. -0.02 ± 0.01 L, p < 0.0001, mean ± SEM). The difference in walking endurance time between bronchodilation and placebo was not statistically significant (Δ15 ± 12 s, p = 0.21), with the upper and lower boundaries of the 95% confidence interval [-9-40 s, 95% CI] within the proposed minimally important difference for this variable (65 s). The ratio of breathing frequency to tidal volume tended to be decreased with bronchodilation during exercise (p = 0.07), indicating a deeper and slower breathing pattern with bronchodilation. Bronchodilation had a significant effect on dynamic hyperinflation at isotime and at peak exercise.
  
  
  CONCLUSIONS
  Bronchodilation did not improve walking endurance in patients with mild COPD despite small physiological benefits of uncertain clinical relevance.
authors.affiliation: Centre de Recherche, Institut Universitaire de Cardiologie et de Pneumologie de Québec, 2725 Chemin Ste-Foy Québec, Université Laval, Québec G1V 4G5, Canada. philippe.gagnon@criucpq.ulaval.ca
authors.forename: Philippe
authors.initials: P
authors.lastname: Gagnon
authors.forename: Didier
authors.initials: D
authors.lastname: Saey
authors.forename: Steeve
authors.initials: S
authors.lastname: Provencher
authors.forename: Julie
authors.initials: J
authors.lastname: Milot
authors.forename: Jean
authors.initials: J
authors.lastname: Bourbeau
authors.forename: Wan C
authors.initials: WC
authors.lastname: Tan
authors.forename: Simon
authors.initials: S
authors.lastname: Martel
authors.forename: François
authors.initials: F
authors.lastname: Maltais
mesh_terms: D000280:Administration, Inhalation; D000368:Aged; D000420:Albuterol / Q000008:administration & dosage*; D000704:Analysis of Variance; D001993:Bronchodilator Agents / Q000008:administration & dosage*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004359:Drug Therapy, Combination; D005080:Exercise Test / Q000379:methods; D017079:Exercise Tolerance / Q000187:drug effects; D005260:Female; D006801:Humans; D009241:Ipratropium / Q000008:administration & dosage*; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D029424:Pulmonary Disease, Chronic Obstructive / Q000188:drug therapy* / Q000503:physiopathology; D052097:Quadriceps Muscle / Q000502:physiology; D012129:Respiratory Function Tests; D016138:Walking / Q000502:physiology*
chemical_list: D001993:Bronchodilator Agents; D009241:Ipratropium; D000420:Albuterol