Acute effect of inhaled iloprost on exercise dynamic hyperinflation in COPD patients: A randomized crossover study.

Abstract

We tested whether the prostacyclin analog inhaled iloprost modulates dead space, dynamic hyperinflation (DH), and systemic inflammation/oxidative stress during maximal exercise in subjects with chronic obstructive pulmonary disease (COPD) who were not selected based on pulmonary hypertension (PH). Twenty-four COPD patients with moderate-severe obstruction (age 59±7 years, FEV1 53±13% predicted) participated in a randomized, double-blind, placebo-controlled crossover trial. Each subject received a single nebulized dose of 5.0μg iloprost or placebo on non-consecutive days followed by maximal cardiopulmonary exercise tests. The primary outcome was DH quantified by end-expiratory lung volume/total lung capacity ratio (EELV/TLC) at metabolic isotime. Inhaled iloprost was well-tolerated and reduced submaximal alveolar dead-space fraction but did not significantly reduce DH (0.70±0.09 vs 0.69±0.07 following placebo and iloprost, respectively, p=0.38). Maximal exercise time (9.1±2.3 vs 9.3±2.2min, p=0.31) and peak oxygen uptake (17.4±6.3 vs 17.9±6.9mL/kg/min, p=0.30) were not significantly different following placebo versus iloprost. A single dose of inhaled iloprost was safe and reduced alveolar dead space fraction; however, it was not efficacious in modulating DH or improving exercise capacity in COPD patients who were not selected for the presence of PH.