COPD patients with severe diffusion defect in carbon monoxide diffusing capacity predict a better outcome for pulmonary rehabilitation

Abstract

Purpose: The aim of this study was to compare the effects of pulmonary rehabilitation (PR) on six-minute walk test (6mWT) between chronic obstructive pulmonary disease (COPD) patients with moderate or severe carbon monoxide diffusion defects. We also evaluated dyspnea sensation, pulmonary functions, blood gases analysis, quality of life parameters and psychological symptoms in both groups before and after pulmonary rehabilitation.

Methods: Patients with COPD underwent a comprehensive 8-week out-patient PR program participated in this study. Patients grouped according to diffusion capacity as moderate or severe. Outcome measures were exercise capacity (6mWT), dyspnea sensation, pulmonary function tests, blood gases analysis, quality of life (QoL) and psychological symptoms.

Results: A total of 68 patients enrolled in the study. Thirty-two (47%) of them had moderate diffusion defect [Tl_CO; 52 (47-61)mmol/kPa] and 36 (53%) of them had severe diffusion defect [Tl_CO; 29 (22-34)mmol/kPa]. At the end of the program, PaO₂ (p=0.001), Modified Medical Research Council dyspnea scale (p=0.001), 6mWT (p<0.001) and quality of life parameters improved significantly in both groups (p<0.05). Also the improvement in Dl_CO (p=0.04) value and FEV₁% (p=0.01) reached a statistically significant level in patients with severe diffusion defect. When comparing changes between groups, dyspnea reduced significantly in patients with severe diffusion defect (p=0.04).

Conclusion: Pulmonary rehabilitation improves oxygenation, severity of dyspnea, exercise capacity and quality of life independent of level of carbon monoxide diffusion capacity in patents with COPD. Furthermore pulmonary rehabilitation may improve Dl_CO values in COPD patients with severe diffusion defect.

Keywords: 6-Minute walk test; DLCO; Dyspnea; Pulmonary function tests; Pulmonary rehabilitation; Quality of life.