The utility of cardiopulmonary exercise testing in evaluating the efficacy of treatment in COPD

Exercise tolerance is one of the major complaints from patients with chronic obstructive pulmonary disease (COPD) and has significant impact on perceived quality of life. Although the etiology of dyspnea in COPD is multifactorial, dynamic hyperinflation during exercise is a major contributor. Although FEV1 has served as an important diagnostic tool, it does not correlate well with patient’s response or exercise performance. The 6 minute walk test is also problematic and has limited use in assessing patient’s response to treatment since the test does not involve a fixed exercise stimulus. Inspired capacity, as a marker of dynamic hyperinflation, measured at various time points during constant load exercise testing does seem to correlate well with exercise endurance time as well as the patient’s level of dyspnea making it a valuable tool to assess the response of various therapeutic modalities used in COPD. In this review we look at the impact of a broad range of therapies used in COPD and their effects on exercise. Bronchodilators, inhaled corticosteroids, oxygen, pulmonary rehabilitation and lung volume reduction surgery all reduce dynamic hyperinflation and improve important patient outcomes