Comparison of the haemodynamic effects of dobutamine with enoximone after open heart surgery in small children.

We have studied 28 children (mean age 13.6 months) undergoing elective cardiac surgery involving a myocardial ischaemic time greater than 60 min. Thirteen received phenoxybenzamine 1 mg kg-1 before cardiopulmonary bypass (CPB) and dobutamine 10 micrograms kg-1 min-1 before discontinuation of CPB; 15 received enoximone 0.5 mg kg-1 followed by an infusion of 10 micrograms kg-1 min-1 before discontinuation of CPB. Haemodynamic variables were measured at intervals for 6 h after CPB. Two patients in each group required additional inotropic support with adrenaline. Heart rates, right and left atrial pressures, mean pulmonary artery pressures and systemic and pulmonary vascular resistance indices were similar in the two groups. Mean arterial pressure was significantly greater in those receiving dobutamine (61.3 (SD 7.6) mm Hg) compared with enoximone (56.2 (5.3) mm Hg) (P < 0.05). Differences in cardiac index (thermodilution) (dobutamine group 2.92 (0.62) litre min-1 m-2; enoximone group 2.55 (0.55) litre min-1 m-2) and left ventricular stroke work index (dobutamine group 13.1 (4.7) g m beat-1 m-2; enoximone group 10.4 (2.7) g m beat-1 m-2) were not statistically significant. Enoximone may be used successfully in these patients to assist discontinuation of CPB and maintain an acceptable haemodynamic state in the early postoperative period but, when used alone, conferred no advantage compared with the combination of dobutamine and phenoxybenzamine.