Intravenous milrinone following cardiac surgery: I. Effects of bolus infusion followed by variable dose maintenance infusion. The European Milrinone Multicentre Trial Group.

The hemodynamic and adverse effects of intravenous milrinone were studied in 99 adult patients (66 men) following elective myocardial revascularization, mitral and/or aortic valve surgery. All patients had a low cardiac output (cardiac index [CI] mean 1.93, range, 1.11 to 2.5 L/min/m2) despite adequate cardiac filling pressure (mean pulmonary capillary wedge pressure [PCWP] 11.5 mmHg, range, 8 to 20 mmHg). Following a period of baseline stability (mean 17.8 minutes, range, 10 to 50 minutes), patients received a bolus infusion of 50 micrograms/kg over 10 minutes. A continuous maintenance infusion of 0.375 (low), 0.5 (mid) or 0.75 (high) micrograms/kg/min was administered for a minimum of 12 hours. Patients were allocated to each dosage group sequentially, not randomly. Hemodynamic measurements were made before the start of milrinone and 15 minutes after the bolus infusion. Further measurements were made at 30, 45, and 60 minutes, and at 3, 6, and 12 hours after the start of treatment. Measurements were also made at 2 and 4 hours after treatment was stopped. The bolus infusion caused significant increases in CI, heart rate (HR), and stroke index (SI), (P < 0.001), and significant falls in PCWP, right atrial pressure (RAP), mean pulmonary artery pressure (mPAP), pulmonary vascular resistance (PVR), mean arterial pressure (MAP), and systemic vascular resistance (SVR) (P < 0.001). These effects were maintained to a significant degree by each of the three maintenance infusion regimens, although the pulmonary vasodilator effects appeared less predictable and more dose dependent. Eighteen patients (19%) had arrhythmias; 16 of these were judged not to be serious events. Two were deemed serious; these were both episodes of fast atrial fibrillation (AF).(ABSTRACT TRUNCATED AT 250 WORDS)