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 mu g 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 (PaO2 69.3 versus 66.8 mm Hg; PaCO2 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)), and VE-versus-VCO2 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.