Effects of iloprost inhalation on exercise capacity and ventilatory efficiency in patients with primary pulmonary hypertension.

BACKGROUND The continuous infusion of prostacyclin has been shown to improve exercise capacity and survival in patients with primary pulmonary hypertension (PPH). Inhalation of iloprost, a stable analog of prostacyclin, might be an alternative therapy for PPH, selectively acting on the pulmonary vascular bed through ventilation-matched alveolar deposition of the drug. We investigated the short-term effects of iloprost inhalation on exercise capacity and gas exchange in patients with PPH. METHODS AND RESULTS In 11 patients with PPH, we performed 2 consecutive cardiopulmonary exercise tests before and after the inhalation of 17 microgram of iloprost. Patients had marked pulmonary hypertension (mean pulmonary artery pressure 65 mm Hg), and inhalation resulted in a decrease in pulmonary vascular resistance (1509 versus 1175 dyne. s(-1). cm(-5), P<0.05). Arterial blood gases remained unchanged (PaO(2) 69.3 versus 66.8 mm Hg; PaCO(2) 29.6 versus 28.8 mm Hg). Iloprost significantly (P<0.05) improved exercise duration (379 versus 438 seconds), peak oxygen uptake (12.8 versus 14.2 mL. kg(-1). min(-1)), VE-versus-V CO(2) slope (58 versus 51.4). CONCLUSIONS The present data show that iloprost inhalation exerts pulmonary vasodilatation and improves symptoms and exercise capacity in patients with PPH. The data also suggest that iloprost inhalation is a suitable treatment for PPH. Whether these effects are maintained during long-term treatment and are paralleled by improvement in prognosis remains to be determined.