Grant: CIHR Fellowship

Lay Abstract: The goal of this project is to examine how lung blood vessel dysfunction contributes to exercise intolerance in patients with chronic obstructive pulmonary disease (COPD). COPD is a condition characterized by airway obstruction and is currently the 4th leading cause of death in Canada. Patients with COPD experience significant shortness of breath, which has been shown to reduce quality of life and physical activity, and increase risk of mortality. Much work has examined breathlessness in moderate and severe COPD, but the reasons for breathlessness in patients with mild COPD are not well understood. Mild COPD patients show an exaggerated breathing response to exercise. Recent work suggests that the increased breathing response during exercise in mild COPD is because of poor matching of regional lung air and blood flow. Researchers have proposed that this imbalance is because of dysfunction of blood vessels in the lungs. Recently the Stickland Laboratory has shown that inhaled nitric oxide dilates blood vessels in the lungs, and therefore reduces shortness of breath, the breathing response to exercise, and improves exercise capacity in mild COPD. These findings suggest that dysfunction of blood vessels in the lungs is an important contributor to exercise intolerance in mild COPD. Building on this previous work, we aim to determine whether oral sildenafil (a pill given clinical to improve blood vessel function in the lungs) improves exercise tolerance in mild COPD patients.