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Friday 01 April 2005

Responsiveness of continuous ratings of dyspnea during exercise in patients with COPD.

By: Mahler DA, Fierro-Carrion G, Mejia-Alfaro R, Ward J, Baird JC.

Med Sci Sports Exerc 2005 Apr;37(4):529-35

PURPOSE: To examine the responsiveness of a new computerized method for patients to provide continuous ratings of dyspnea during exercise in patients with chronic obstructive pulmonary disease (COPD). METHODS: In this randomized, double-blind study the effects of an inhaled bronchodilator (BD), albuterol/ipratropium bromide solution, were compared with normal saline (NS) in 30 patients with COPD (age, 66+/-9 yr; forced expiratory volume in 1 s, 48+/-14% pred). At visit 1, patients were familiarized with the cycle ergometer and computer, monitor, and mouse system to provide continuous ratings of dyspnea during exercise. At subsequent visits 2-3 d apart, patients performed pulmonary function tests followed by incremental ramp (15 W.min-1) and, 1 h later, constant work (at 55% of maximal work capacity) exercise tests. RESULTS: During incremental exercise the slopes of VO2:dyspnea and VE:dyspnea regressions were significantly lower, and patients exercised longer (Delta=0.4 min; P=0.003) with BD therapy compared with NS. During constant work exercise there was a significant reduction in dyspnea at the same exercise duration (5.0+/-2.8 vs 6.2+/-2.8 units on the 0-10 category-ratio scale; P=0.02) and patients exercised longer (Delta=0.9 min; P=0.04) with BD therapy. Changes in lung function at rest did not correlate significantly with changes in dyspnea ratings during exercise. CONCLUSIONS: Continuous ratings of dyspnea were responsive to inhaled bronchodilator therapy during both incremental and constant work exercise tests in patients with symptomatic COPD.

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