Objective: To study the effects of incremental concentrations of inhaled aerosolized prostacyclin (PGI2) on pulmonary and systemic hemodynamics after cardiac surgery or heart transplantation.
Design: Pharmacodynamic dose-response study.
Setting: Cardiothoracic intensive care unit (ICU) at a university hospital.
Participants: Nine patients with pulmonary hypertension after cardiac surgery or heart transplantation and an elevated pulmonary vascular resistance (PVR) (> 20 dynes.sec.cm-5) treated in the ICU with inotropic support were studied.
Interventions: Inhaled prostacyclin was administered at concentrations of 2.5, 5.0, and 10.0 micrograms/mL using conventional systems for nebulization.
Measurements and main results: Pulmonary and systemic hemodynamics as well as right ventricular (RV) function variables (n = 3) were measured before, during, and 10 and 20 minutes after inhalation of PGI2. Inhaled PGI2 induced a dose-dependent decrease in PVR and the transpulmonary gradient (which decreased by -29% and -26%, respectively) at an inhaled concentration of 10 micrograms/mL. Inhaled PGI2 caused no changes in systemic vascular resistance. Central venous pressure decreased during PGI2 inhalation with no change in stroke volume, indicating an improvement in RV performance, which was particularly obvious in one patient with RV failure after heart transplantation. Twenty minutes after discontinuation of inhaled PGI2, hemodynamic variables returned to baseline.
Conclusions: Inhaled PGI2 induces a dose-dependent selective pulmonary vasodilation and may improve RV performance after cardiac surgery complicated by pulmonary hypertension and RV failure.