Pulmonary rehabilitation ameliorates regional lung function in chronic obstructive pulmonary disease: a prospective single-arm clinical trial

BACKGROUND: Pulmonary rehabilitation (PR) is a widely recognized nonpharmacologic therapy for chronic obstructive pulmonary disease (COPD), but most of the current studies on whether PR can benefit COPD patients are based on the evaluation of symptoms and pulmonary function, which is limited to a certain extent. Because COPD is characterized by potential regional lung changes in morphology and pathophysiology, this study was designed to evaluate the effects of individualized PR on regional lung function in patients with stable COPD. METHODS: In this study, patients with stable COPD who met the criteria were included, and they were treated with PR for 2 weeks using the respiratory rehabilitation training instrument. The symptoms, and global and regional lung function before and after 2 weeks of PR treatment were evaluated using surveys, spirometry, and electrical impedance tomography (EIT), respectively. The spatial coefficient of variation (CV) of regional spirometry parameters were calculated to quantify spatial heterogeneity of lung function. Temporal inhomogeneity was determined by the regional expiration time. RESULTS: A total of 34 participants were recruited in this study, of whom 24 completed the PR. After 2 weeks of intervention, the modified Medical Research Council (mMRC) dyspnea scale and the COPD assessment test (CAT) score was significantly lower compared to those measured before the treatment (2.3±1.17 vs. 2.1±0.93, P=0.034; and 15.0±7.18 vs. 10.9±6.06, P<0.001, respectively). Global spirometry forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), FEV1 predicted percentage (%pred), and peak expiratory flow (PEF) were significantly better than they were pre-rehabilitation (2.1±0.86 vs. 2.3±0.90 L, P=0.018; 1.2±0.65 vs. 1.4±0.66 L, P=0.001; 46.8%±23.16% vs. 51.4%±24.41%, P<0.001; and 3.1±1.80 vs. 3.8±2.23 L/s, P=0.005, respectively). In addition, the CV for regional FEV1/FVC was significantly decreased after the PR treatment (0.26±0.161 vs. 0.17±0.077, P=0.002). Regional lung ventilation was more homogeneous and regional expiration time was shorter after 2 weeks of the PR treatment. CONCLUSIONS: Two weeks of PR treatment can improve both spatial and temporal regional ventilation in COPD. In addition, EIT may be useful in developing individualized PR treatment program to improve regional lung function in COPD.