A comparison of the acute hemodynamic effects of inhaled nitric oxide and aerosolized iloprost in primary pulmonary hypertension

OBJECTIVE We sought to compare the acute hemodynamic effects of inhaled nitric oxide (NO) and aerosolized iloprost in primary pulmonary hypertension (PPH). BACKGROUND Inhalation of the stable prostacyclin analogue iloprost has recently been described as a novel therapeutic strategy for PPH and may offer an alternative to continuous intravenous infusion of prostacyclin or inhalation of NO. METHODS During right heart catheterization, 35 patients with PPH sequentially inhaled 40 ppm of NO and 14 to 17 μg of iloprost, and the effects on hemodynamics and blood gases were monitored. RESULTS Both NO and iloprost caused significant increases in cardiac output, mixed-venous oxygen saturation and stroke volume as well as significant decreases in pulmonary artery pressure and pulmonary vascular resistance, whereas only inhaled iloprost significantly increased the arterial Pimage2 (p = 0.01). Compared with inhaled NO, aerosolized iloprost was more effective in reducing pulmonary artery pressure (−8.3 ± 7.5 mm Hg vs. −4.3 ± 8.8 mm Hg; p = 0.0001) and the pulmonary vascular resistance (−447 ± 340 dynes·s·cm−5 vs. −183 ± 305 dyne·s·cm−5; p < 0.0001). Furthermore, aerosolized iloprost caused a significantly greater increase of the cardiac output compared with NO (+0.7 ± 0.6 liter/min vs. +0.3 ± 0.4 liter/min; p = 0.0002) and had a more pronounced effect on the mixed-venous oxygen saturation (p = 0.003). CONCLUSIONS During acute drug testing, aerosolized iloprost was more potent than inhaled NO as a pulmonary vasodilator in PPH at the doses used in this study.