THE EFFECT OF MILRINONE ON HEMODYNAMICS AND LEFT-VENTRICULAR FUNCTIONAFTER EMERGENCE FROM CARDIOPULMONARY BYPASS

Although milrinone effectively increases cardiac function, few studies have specifically evaluated its efficacy during cardiac surgery. We i nvestigated the effects of milrinone on hemodynamics and left ventricu lar function in cardiac surgical patients who were already treated wit h catecholamines. Thirty-seven patients undergoing cardiac surgery wer e studied. Immediately after emergence from cardiopulmonary bypass (CP B), patients were randomly assigned to a control group (n = 10) or to one of these milrinone groups: milrinone 50 mu g/kg intravenously (n = 8), 50 mu g/kg + 0.5 mu g . kg(-1) . min(-1) (it = 10), or 75 mu g/kg + 0.75 mu g.kg . min(-1) (n = 9). Hemodynamics and transesophageal ec hocardiogram were recorded while constant filling pressures were maint ained by volume reinfusion from the CPB reservoir. Arterial blood samp les were obtained for the measurement of milrinone plasma concentratio ns and to determine the dose response curve. In all three milrinone gr oups, cardiac index and velocity of circumferential fiber shortening ( Vcfc) significantly increased from the baseline, and both were signifi cantly higher at 5 and 10 min than those in the control group. The pla sma concentration of milrinone with half of maximum increase in Vcfc w as 139.3 ng/mL based on the dose-response curve. Thus, milrinone impro ves hemodynamics and left ventricular function when constant loading c onditions are maintained.