Diaphragmatic excursion correlates with exercise capacity and dynamic hyperinflation in COPD patients

Although the pathophysiological mechanisms involved in the development of dyspnoea and poor exercise tolerance in patients with COPD are complex, dynamic lung hyperinflation (DLH) plays a central role. Diaphragmatic excursions can be measured by ultrasonography (US) with high intra- and interobserver reliability. The objective of this study was to evaluate the effect of diaphragmatic excursions as assessed by US on exercise tolerance and DLH in patients with COPD. Patients with COPD (n=20) and age-matched control subjects (n=20) underwent US, which was used to determine the maximum level of diaphragmatic excursion (DE ). Ventilation parameters, including the change in inspiratory capacity (ΔIC), were measured in the subjects during cardiopulmonary exercise testing (CPET). We examined the correlations between DE and the ventilation parameters. The DE of patients with COPD was significantly lower than that of the controls (45.0±12.8 mm 64.6±6.3 mm, respectively; p