Strategies to reduce dynamic hyperinflation in chronic obstructive pulmonary disease.

The chief complaint of many patients with chronic obstructive pulmonary disease (COPD) is that they are no longer able to carry out or maintain an activity of which they were previously capable [1, 2]. The mechanism of activity limitation is now felt to be multifactorial, related to muscle dysfunction as well as to pulmonary factors. A key concept is that activity limitation (or exercise intolerance) in COPD is linked to hyperinflation, particularly dynamic hyperinflation. Discovery of this link between airway obstruction and activity limitation has led us to seek physiologic-based strategies to reduce hyperinflation and, thereby, improve the exercise tolerance of patients with COPD. Four interventions that reduce hyperinflation during exercise have been identified. These are bronchodilator therapy, inhalation of supplemental oxygen or a helium/oxygen mixture, and rehabilitative exercise programs.