[The effects of milrinone on hemodynamics in patients undergoing cardiac surgery]

The phosphodiesterase inhibitor, milrinone is used to treat low cardiac output syndrome, especially after cardiac surgery. But there were few reports about the precise hemodynamic effects at separation from cardiopulmonary bypass (CPB). We examined the hemodynamic effects of milrinone in 24 patients undergoing elective coronary artery bypass graft (CABG). Patients were assigned to the milrinone group (n = 12) and the control group (n = 12). Before separation from CPB, milrinone was administered as a loading dose of 50 micrograms.kg-1 into the reservoir of CPB at rectal temperature 33.5 degrees C and simultaneously a continuous infusion of 0.5 microgram.kg-1.min-1 was started. In addition, dopamine and nitroglycerine were administered in both groups. Hemodynamic measurements were performed before CPB, just after the weaning from CPB, 15, 30, 60 minutes after the weaning from CPB. Cardiac index increased significantly (P < 0.01) in the milrinone group as compared with the control group. Systemic vascular resistance index and mean arterial pressure decreased significantly (P < 0.0001, P < 0.05, respectively) in the milrinone group as compared with the control group. There were no significant differences in heart rate, mean pulmonary arterial pressure, pulmonary artery occlusion pressure, mean right atrial pressure, stroke volume index, and pulmonary vascular resistance index between the two groups. These hemodynamic effects showed that milrinone supported cardiac performance after CPB for CABG.