Hemodynamic effects of dobutamine after cardiopulmonary bypass in children

The synthetic inotropic agent, dobutamine, has reportedly increased cardiac output in adults after cardiopulmonary bypass with minimal side effects. Its use in children, after surgical correction of congenital heart disease, was tested by infusing the drug at 1, 4, 7, and 10 micrograms/kg x min in 11 children. While significant increases in cardiac index above control (23, 23, and 16% at 4, 7, and 10 micrograms/kg x min, respectively) were observed, this was achieved at the expense of significant increases in heart rate (15, 24, and 10%). This increase in heart rate (47% in one child) necessitated discontinuing the infusion in 4 subjects. There were also significant increases in systolic and mean blood pressure with no change in stroke volume or peripheral vascular resistance. The authors conclude that in children, dobutamine is an effective inotropic agent acting principally by stimulating beta 1-receptors in the myocardium producing a predominantly chronotropic effect without significant changes in peripheral vascular resistance. Given the intrinsically higher heart rate of children, the levels of tachycardia produced by the drug in some instances reach unacceptable levels and as such, may make dopabutamine unsuitable for use in children after cardiopulmonary bypass.