A bolus dose of 1.5 mg/kg amrinone effectively improves low cardiac output state following separation from cardiopulmonary bypass in cardiac surgical patients

Background : The aim of this study was to evaluate the efficacy of 1.5 mg/kg bolus of amrinone on low cardiac output (CO) state following emergence from cardiopulmonary bypass (CPB) in cardiac surgical patients.
Methods : Immediately after emergence from CPB, 14 patients with a cardiac index (CI) less than 2.2 l min^-1 m^-2 despite administration of inotropes and nitroglycerin, received 1.5 mg/ kg amrinone over 3 min without changing catecholamine infusion rates (amrinone group). Hemodynamics and left ventricular short axis views with transesophageal echocardiography were recorded at baseline, 3, 5, and 10 min following amrinone administration. Left ventricular filling volumes were maintained constant by volume reinfusion from the CPB reservoir. We matched the data of the amrinone group with the other 14 patients who did not receive amrinone (non-amrinone group) to evaluate the efficacy of amrinone in low CO state.
Results : At baseline, CI (1.8±0.1 1 min^-1 m^-2) in the amrinone group was significantly lower than CI (3.0±0.2) in the non-amrinone group. Following amrinone administration, CI and velocity of circumferential fibershortening corrected for heart rate (Vcfc) significantly increased, and systemic vascular resistance index and pulmonary vascular resistance index significantly decreased from the baseline within 10 min without changes in heart rate, mean arterial blood pressure, or pulmonary artery occlusion pressure, and became equivalent with those of the non-amrinone group.
Conclusions : A 1.5 mg/kg amrinone loading dose to patients in a low CO state, despite catecholamine therapy immediately after emergence from CPB, effectively improves ventricular function when loading conditions are maintained constant.