Hemodynamic effects of dobutamine and dopexamine after cardiopulmonary bypass in pediatric cardiac surgery*

BACKGROUND: After surgical repair of congenital heart disease, inotropic support is sometimes necessary to wean from cardiopulmonary bypass. In pediatric cardiac surgery, dobutamine and dopamine are often used as inotropic support. Dopexamine is a synthetic catecholamine, which has positive inotropic and vasodilating properties. Because the hemodynamic effects of catecholamines are modified after cardiopulmonary bypass, the aim of this study was to investigate the effects of dobutamine and dopexamine on cardiac index and systemic vascular resistance index after cardiopulmonary bypass in pediatric cardiac surgery. METHODS: The study was performed in a prospective, randomized, and double-blinded cross-over design. The investigation included 11 children for elective, noncomplex congenital heart surgery. After weaning from cardiopulmonary bypass and a 20-min period of steady state, children received either 2.5 microg x kg(-1) x min(-1) dobutamine or 1 microg x kg(-1) x min(-1) dopexamine for 20 min. Cardiac index (transpulmonary thermodilution), mean arterial pressure, central venous pressure, stroke volume, systemic vascular resistance, and central venous oxygen saturation were determined. The primary outcome variable was cardiac index. RESULTS: No difference in cardiac index was observed between the two groups (P = 0.594). Both drugs increased cardiac index, dopexamine from 3.9 +/- 0.6 to 4.7 +/- 0.8 l x min(-1) x m(-2) (P = 0.003) and dobutamine from 4.1 +/- 0.7 to 4.8 +/- 0.7 l x min(-1) x m(-2) (P = 0.004). During treatment with dobutamine, children presented with significantly higher mean arterial pressure (P = 0.003) and systemic vascular resistance index (P = 0.026). CONCLUSIONS: This trial demonstrates that low-dose dobutamine and dopexamine both increase cardiac index during pediatric cardiac surgery but with different hemodynamic effects.