Effects of inspiratory muscle training on dyspnoea in severe COPD patients during pulmonary rehabilitation: controlled randomised trial

The benefit of inspiratory muscle training (IMT) combined with a pulmonary rehabilitation programme (PRP) is uncertain. We aimed to demonstrate that, in severe and very severe chronic obstructive pulmonary disease (COPD) patients, IMT performed during a PRP is associated with an improvement of dyspnoea. In a single-blind randomised controlled trial, 150 severe or very severe COPD patients were allocated to follow PRP+IMT versus PRP alone. The evaluations were performed at inclusion and after 4 weeks. The primary outcome was the change in dyspnoea using the Multidimensional Dyspnoea Profile questionnaire at the end of a 6-min walk test (6MWT) at 4 weeks. Secondary outcomes were changes in dyspnoea using the Borg (end of the 6MWT) and modified Medical Research Council scales and in functional parameters (maximal inspiratory pressure (PImax), inspiratory capacity, 6MWT and quality of life). All analyses were performed on an intention-to-treat basis. Dyspnoea decreased significantly in both groups; however, the improvement of dyspnoea was not statistically different between the two groups. We only found a statistically significant greater increase of PImax after IMT+PRP than after PRP alone. In this trial including severe or very severe COPD patients, we did not find a significant benefit of IMT during PRP+IMT as compared to PRP alone on dyspnoea, despite a significantly higher improvement of PImax in the IMT group.