Iloprost Improves Gas Exchange and Exercise Tolerance in Patients with Pulmonary Hypertension and Chronic Obstructive Pulmonary Disease

Abstract

Background: Nonselective systemic vasodilators worsen ventilation perfusion (V/Q) matching and gas exchange in patients with chronic obstructive pulmonary disease (COPD). Inhaled iloprost has the potential to act preferentially in ventilated regions of the lung, thereby reducing pulmonary hypertension (PH) while alveolar ventilation is still maintained. Objectives: To investigate the acute effects of inhaled iloprost on V/Q matching in patients with COPD and PH. Methods: Ten males with COPD and PH on echocardiography were evaluated before and after inhaling 2 doses of iloprost (2.5 µg). Measurements included lung function, arterial blood gas, 6-min walk test (6MWT) as well as ventilatory equivalents for oxygen (VE/VO2) and carbon dioxide (VE/VCO2) taken at baseline, 30 min following each dose of iloprost, and 2 h after the second dose. Results: Mean differences in VE/VCO2 and VE/VO2 were –13.3 (95% CI –36.5 to –2.7; p = 0.002) and –15.0 (95% CI –36.7 to –0.4; p = 0.02), respectively, and the mean change in (A-a) gradient was –3.7 mm Hg (95% CI –6.1 to –1.0; p = 0.01) after a single dose of iloprost, whereas mean improvement in 6MWT was 49.8 m (95% CI 14.8 to 84.7; p = 0.02). Arterial blood gas, venous admixture, dead space fraction and lung functions were maintained after iloprost. The effects of iloprost were reproducible after the second dose. All measurements returned to baseline 2 h after the last dose. No adverse effects on systemic blood pressure or oxygen saturation were seen. Conclusions: Iloprost inhalation was safe in patients with COPD and PH, and was associated with improved V/Q matching and exercise tolerance.