PURPOSE: This study investigated the possible mechanisms for the expected improvement in dyspnea with pulmonary rehabilitation. METHODS: Lung function, clinical ratings of dyspnea, and exercise responses were studied in 44 patients with chronic obstructive pulmonary disease who participated in an outpatient program consisting of 1.5 hours per week of supervised education, breathing training, and upper/lower extremity exercise. RESULTS: After rehabilitation, there were significant increases in forced expiratory volume in 1 second (FEV1, 7%; P = .02), maximal inspiratory mouth pressure (PImax, 17%; P < .001), and the transition dyspnea index focal score (3.4; P < .001) and a significant decrease in the slope of dyspnea/power (0.12 versus 0.09; P = .001) during exercise. Patients who demonstrated > or = 0 mL of change in FEV1 or > or = 5 cm H2O of change in PImax exhibited significant decreases in the slopes for dyspnea/power. CONCLUSIONS: After pulmonary rehabilitation, there was a significant improvement in dyspnea. Although there was no evidence of a physiologic training response or enhanced mechanical efficiency, the modest increase in FEV1 and the increase in respiratory muscle strength appeared to contribute to the reduction in dyspnea.
PURPOSE: This study investigated the possible mechanisms for the expected improvement in dyspnea with pulmonary rehabilitation. METHODS: Lung function, clinical ratings of dyspnea, and exercise responses were studied in 44 patients with chronic obstructive pulmonary disease who participated in an outpatient program consisting of 1.5 hours per week of supervised education, breathing training, and upper/lower extremity exercise. RESULTS: After rehabilitation, there were significant increases in forced expiratory volume in 1 second (FEV1, 7%; P = .02), maximal inspiratory mouth pressure (PImax, 17%; P < .001), and the transition dyspnea index focal score (3.4; P < .001) and a significant decrease in the slope of dyspnea/power (0.12 versus 0.09; P = .001) during exercise. Patients who demonstrated > or = 0 mL of change in FEV1 or > or = 5 cm H2O of change in PImax exhibited significant decreases in the slopes for dyspnea/power. CONCLUSIONS: After pulmonary rehabilitation, there was a significant improvement in dyspnea. Although there was no evidence of a physiologic training response or enhanced mechanical efficiency, the modest increase in FEV1 and the increase in respiratory muscle strength appeared to contribute to the reduction in dyspnea.