Evaluation of exercise capacity in chronic obstructive pulmonary disease patients with pulmonary hypertension

Abstract

Abstract Background Chronic obstructive pulmonary disease (COPD) is ordinarily associated with social and economic burden. Pulmonary hypertension attributed to COPD varies greatly among studies; and accounts for worse quality of life and hence increased morbidity and mortality. Aim This study aimed to evaluate impact of pulmonary hypertension on exercise capacity, and possible predictors for exercise intolerance among COPD patients. Methods Patients suffering from COPD (73 patients) were grouped according to echocardiographic assessment for the presence of pulmonary hypertension into two groups. The assessment included full clinical history, mMRC dyspnea scale, COPD assessment test, arterial blood gases before and after exercise testing, and assessment of resting pulmonary function test. Also transthoracic echocardiography, cardiopulmonary exercise testing (CPET) using incremental treadmill exercises protocol was done for all participants. Results A total of 39 (53.4%) COPD patients have pulmonary hypertension. COPD patients with pulmonary hypertension had significantly lower parameters of pulmonary function tests either pre or postbronchodilator; significantly lower pH, PaO2 and SaO2 either before or after CPET. It was found that all parameters of metabolic response during exercise were significantly lower among COPD-PH patients (P<0.001). Pulmonary artery systolic pressure (PASP) showed significant negative correlations with peak VO2 (r=−0.514, P<0.001), VO2/kg (r=−0.443, P<0.001), oxygen pulse (% predicted) (r=−0.459, P<0.001), oxygen saturation post exercise (r=−0.427, P<0.001). Also PASP showed significant positive correlation with VE/VO2 (at peak) (r=0.374, P=0.001), VE/VCO2 (at peak) (r=0.609, P<0.001). Predictors of poor exercise capacity among COPD patients included in the study were COPD-PH group (OR=8.84, 95%CI= 1.79–43.65), PASP (OR=1.11, 95% CI=1.02–1.15), forced expiratory volume (FEV1)% (OR=0.89, 95% CI=0.84–0.95) and mMRC (OR=3.10, 95% CI=1.13–8.47), CAT assessment (OR=1.37, 95% CI=1.14–1.65), MVV L/min (OR=0.91, 95% CI=0.86–0.96) and mean PAP (OR=1.16, 95% CI=1.11–1.29). Conclusion Pulmonary hypertension in patients with COPD is negatively correlated with exercise capacity, specifically peak VO2 percent predicted. Furthermore, pulmonary hypertension had a significant impact on gas exchange. Assessment of pulmonary hypertension using echocardiography among COPD patients is a valuable tool for predicting exercise impairment.