Comparison of the hemodynamic effects of amrinone in patients who requiredlow-to-moderate-dose and high-dose catecholamines after cardiac valve replacement

Objectives: To determine hemodynamic response to amrinone in patients after cardiac surgery, in relation to the postoperative cardiac function, which was indicated by the required doses of catecholamines. Design: Prospective clinical study. Setting: Surgical intensive care unit in a university hospital. Patients: Fourteen patients who required a low-to-moderate dose of dopamine and dobutamine (group L) and 14 patients who required a high dose of dopam ine and dobutamine (group H) after cardiac valve replacement, Interventions: A loading dose of amrinone (0.75 mg/kg) was administered dur ing a 15-min period and the continuous infusion was followed incrementally by doses of 5, 10, and 20 mu g/kg/min every 60 mins on the first postoperat ive day. Measurements and Main Results: Hemodynamic variables were determined by the radial and pulmonary artery catheters at a dose of 0, 5, 10, and 20 mu g/k g/min. Two-way repeated-measures analysis of variance showed significant in teraction in the two groups in cardiac index and mean systemic arterial pre ssure, Cardiac index increased in a dose-dependent manner in group L but wa s unchanged in group H. Systemic vascular resistance index decreased in a d ose-dependent manner in both groups. The mean systemic arterial pressure de creased in group L at a dose of 5 mu g/kg/min and returned to the baseline level at doses of 10 and 20 mu g/kg/min. On the other hand, the mean system ic arterial pressure significantly decreased in group H at a dose of 20 mu g/kg/min. Conclusions: The inotropic effects of amrinone after cardiac valve replacem ent may be associated with the postoperative myocardial reserve, which was indicated by the required doses of catecholamines, although a similar vasod ilative effect was observed in both groups.