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

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.

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.

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.

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.