Department of Kinesiology & Physical Education, McGill University
Physiological mechanisms of dyspnea relief and improved exercise tolerance after treatment with oral morphine in patients with advanced chronic obstructive pulmonary disease (COPD)
Chronic obstructive pulmonary disease (COPD) is a progressive disease of the lungs and airways, causing shortness of breath (dyspnea) and exercise intolerance. Conventional efforts to alleviate these symptoms have focused on dilating the airways (eg, bronchodilators), reducing the drive to breathe (eg, supplemental oxygen), or both of these in combination. Nevertheless, many COPD patients remain incapacitated by dyspnea and intolerant to exercise, despite receiving optimal therapy for management of their disease.
Under these circumstances, clinical practice guidelines recommend that pain-relieving (opioid) drugs, such as morphine, may be used to help to manage symptoms in these patients. Indeed, the results of several published studies provide evidence to suggest that administration of either morphine or codeine improves dyspnea and exercise capacity by up to 20% in patients with COPD. Unfortunately, the physiological mechanisms of these improvements remain poorly understood and largely understudied.
The purpose of the proposed research is to test the hypothesis that morphine (0.1 mg/kg) improves exertional dyspnea and exercise performance in patients with advanced COPD, and to examine potential physiological mechanisms underlying these improvements. This information becomes crucial if we are to optimize management of chronic activity-related dyspnea in COPD and achieve our ultimate goal of improving functional capacity and quality of life in these patients.