Effects of captopril combined with oxygen therapy at rest and on exercise in patients with chronic bronchitis and pulmonary hypertension

The aim of this study was to determine the effects of captopril combined with oxygen therapy on pulmonary hemodynamics and gas exchange in chronic obstructive pulmonary disease (COPD) patients with pulmonary hypertension. Eleven subjects, with severe airflow obstruction (FEV1/FVC: 42 +/- 11%) and chronic respiratory failure (PaO2: 54 +/- 6 mm Hg, PaCO2: 46 +/- 8 mm Hg) treated with long-term oxygen, underwent two successive hemodynamic and arterial gas studies, at rest and during exercise. All the studies were performed whilst the patients were breathing oxygen, at rest and during exercise and 1 h after intake of 12.5 mg of captopril. The second study was performed in 9 out of the 11 patients after 8 weeks of treatment with 12.5 mg captopril 3 times daily. At rest, there was no significant effect of captopril. Mean pulmonary arterial pressure (PAP) showed a trend towards decrease after 8 weeks treatment. During exercise, there was a statistically significant decrease of mean PAP, pulmonary capillary wedge pressure and total pulmonary vascular resistance, without any deleterious effect on blood gases. However, the clinical significance of these variations during exercise is poor. We conclude that a low dose of captopril associated with oxygen therapy has no significant clinical effect on pulmonary hemodynamics at rest and during exercise in COPD.