Enhanced diaphragm excursion and exercise tolerance in COPD patients through inspiratory muscle training after standardised pulmonary rehabilitation: randomised controlled trial

Abstract

ObjectiveInspiratory muscle training (IMT) is used to improve inspiratory muscle strength in patients with chronic obstructive pulmonary disease (COPD). However, the effect of IMT on diaphragmatic function has not yet been thoroughly evaluated. This study aimed to evaluate the effect of IMT on maximum diaphragmatic excursion (DEmax) using ultrasonography in patients with COPD.MethodsThis was a single-center, randomised, prospective, parallel-group, unblinded controlled trial involving 38 participants with stable COPD. Participants underwent a standardised 12-week pulmonary rehabilitation (PR) program followed by a 12-week IMT program, consisting of home-based IMT and low-frequency outpatient PR sessions supervised by physiotherapists (once every 2 weeks),versuslow-frequency outpatient PR alone as a control. The DEmaxand exercise tolerance were measured.ResultsOut of the 38 patients initially enrolled in the PR program, 33 successfully completed it and were subsequently randomised to the IMT program. Finally, 15 (94%) and 14 (88%) patients from the IMT and control groups, respectively, completed the study. Following the IMT program, DEmaxincreased in the IMT group (50.1±7.6 mm to 60.6±8.0 mm, p<0.001), but not in the control group (47.4±7.9 mm to 46.9±8.3 mm, p=0.10). Changes in DEmaxand exercise tolerance (peak VO2) were greater in the IMT group than in the control group (both p<0.01).ConclusionsIMT following the PR program improved DEmaxand exercise tolerance. Therefore, DEmaxmay be an important outcome of IMT.