The aim of this study is to compare the role of nitroglycerine, milrinone, and iloprost as pulmonary vasodilators administered through the inhalation route in reducing pulmonary arterial hypertension (PAH) and facilitating weaning from cardiopulmonary bypass (CPB) in cardiac surgical patients.Methods
In total, 75 cardiac surgical patients with preexisting PAH were randomized to receive nitroglycerine (group N; n=25), milrinone (group M; n=25), or iloprost (group I; n=25) by inhalation before the initiation of and during weaning from CPB. Hemodynamic parameters including heart rate (HR), mean systemic and pulmonary arterial pressures, systemic and pulmonary (PVR) vascular resistances, cardiac index, and mixed venous oxygen saturation were measured before drug inhalation (T0), after drug inhalation (T1), after weaning from CPB (T2), and at sternal closure (T3). The incidence of difficult weaning off CPB and the need for pharmacologic and mechanical cardiovascular support were also recorded.Results
PVR and mean pulmonary arterial pressure were significantly reduced in all groups at all time points compared with the baseline values. This reduction was significantly greater in groups M and I compared with group N at T1, T2, and T3. Cardiac index and mixed venous oxygen saturation were significantly higher in groups M and I at all time points compared with the baseline values and with group N. Heart rate, mean systemic arterial pressure, and systemic vascular resistance were stable in all groups at all time points. The incidence of difficult weaning from CPB, doses of inotropic, vasopressor, and inodilator support, and the incidence of mechanical cardiovascular support were significantly lower in the milrinone and iloprost groups compared with the nitroglycerine group.Conclusion
Inhaled nitroglycerine, milrinone, and iloprost are effective in reducing PVR and PAP with pulmonary vascular selectivity in high-risk patients with PAH undergoing cardiac surgery under CPB. Aerosolized milrinone and iloprost are superior to nitroglycerine as they increase the cardiac output, facilitating weaning from CPB.