Comparing cardiopulmonary exercise testing in severe COPD patients with and without pulmonary hypertension

Purpose: To determine (i) the effect of PH on exercise capacity, gas exchange and oxygen pulse; (ii) the variables that correlate with mean pulmonary artery pressure (mPAP) in severe COPD patients. Methods: We reviewed 98 severe COPD patients who had pulmonary function, right heart catheterisation, and cardiopulmonary exercise testing (CPET) performed within six months of each other. PH was defined by a resting mPAP > 25. mmHg. COPD patients with and without PH were compared using the independent samples t-test and Mann-Whitney U test. Pearson correlation coefficients were used to assess the relationship between continuous variables. Results: PH was present in 32% of patients and the majority of PH was mild (mPAP, 25-35. mmHg). Peak workload, oxygen uptake and oxygen pulse on CPET were significantly lower in the PH group. Mean PAP was found to inversely correlate with peak oxygen uptake, with a tendency towards lower six-minute walk distance. No difference between two groups was seen in any of the gas exchange variables. Conclusion: In severe COPD, there is a relatively high percentage of PH which causes a decrease in exercise capacity and oxygen pulse without significantly altered ventilation as measured by CPET. Lower than expected exercise performance without a change in pulmonary function may indicate a need for evaluation for possible PH.