Dynamic hyperinflation in patients with severe asthma compared to healthy adults.

Despite current medical management, exertional breathlessness is commonly experienced by adults with severe asthma limiting their exercise tolerance. A cardiopulmonary exercise test may help identify the reasons for these symptoms to guide appropriate management and evaluate new interventions. For instance, exhalation can be interrupted by the next inspiration resulting in an increased end expiratory lung volume. Increasing end expiratory lung volume as ventilation increases is defined as dynamic hyperinflation.1 Although there are reports of dynamic hyperinflation in asthma,2, 3, 4 the frequency, severity and impact by exercise platform is unknown.