Comparison of the effects of dobutamine and milrinone on hemodynamic parameters and oxygen supply in patients undergoing cardiac surgery with low cardiac output after anesthetic induction.

BACKGROUND AND OBJECTIVES Several classes of inotropic drugs with different hemodynamic effects are used in the treatment of low cardiac output in patients with diastolic dysfunction undergoing cardiac surgery. The objective of the present study was to compare the effects of dobutamine and milrinone on hemodynamic parameters and oxygen supply in this population of patients. METHODS After approval by the Ethics Committee of the institution and signing of the informed consent, 20 patients undergoing cardiac surgery with cardiac index < 2 L*min(-1)*m(2) after anesthetic induction and placement of a pulmonary artery catheter were randomly divided to receive dobutamine 5 microg*kg(-1). min(-1) (n = 10), or milrinone 0.5 microg*kg(-1)*min(-1) (n = 10). Hemodynamic parameters were measured after anesthetic induction and after 30 and 60 minutes, and arterial and venous blood gases were measured at baseline and 60 minutes. Non-paired Student t test or two-way ANOVA for repeated measurements was used to compare the data. RESULTS Dobutamine and milrinone promoted significant increases in cardiac index (56% and 47%) and oxygen supply (53% and 45%), and reduction in systemic (33% and 36%) and pulmonary (34% and 19%) vascular resistance, respectively. However, statistically significant differences were not observed between both drugs. CONCLUSIONS Both inotropic drugs were similarly effective in restoring tissue blood flow and oxygen supply to adequate levels in patients with low cardiac output undergoing cardiac surgery.