Slow induction of milrinone after coronary artery bypass grafting

The aim of this study was to evaluate the hemodynamic effects of a slow induction of milrinone after open heart surgery. Twenty patients who underwent elective coronary artery bypass grafting were randomized into two groups, with 10 patients receiving a continuous infusion of milrinone (5 microg/kg/min) (group M), and 10 patients undergoing treatment without milrinone (group C). This is a preliminary study for evaluating the efficacy of a slow induction of milrinone, so patients in low cardiac output state were excluded. A continuous infusion without an initial loading dose was initiated in the intensive care unit. Hemodynamic parameters and the concentration of milrinone were measured 90 minutes and 3 hours after initiation of the milrinone infusion. A significant decrease in arterial pressure occurred at 3 hours in group M, and both the systemic vascular resistant indices decreased significantly (p<0.05) at 90 minutes. No significant changes occurred in group C. Cardiac index and heart rate increased significantly (p<0.05) in group M, but were unchanged in group C. No significant change in double product was observed in either group. Hypotension (systolic blood pressure less than 100 mmHg) or arrhythmia did not occur in group M. The concentration of milrinone at 90 minutes and 3 hours was 97+/-22 and 124+/-27 ng/ml, respectively. A slow induction of milrinone is safe and effective in patients following cardiac surgery.