Comparison of dopamine and dobutamine in patients requiring postoperative circulatory support.

We compared dopamine and dobutamine following cardiac surgery in a sequential cross-over study of 9 patients who required inotropic support after volume replenishment. Seven patients had mitral valve replacement, 2 with simultaneous coronary revascularization (CABG), and 1 each with simultaneous tricuspid annuloplasty and aortic valve replacement; 1 had isolated CABG and 1 had repair of a postinfarction ventricular septal defect. Heart rate, right and left atrial pressures, pulmonary and mean arterial pressure, systemic and pulmonary vascular resistance, and cardiac index were measured and calculated. Inotropic support with dopamine or dobutamine was begun for treatment of low cardiac index within 12 hours postoperatively. Measurements were made after 20 minutes on either agent at 5-10 micrograms/kg per min when cardiac output and general clinical state were stable. Each patient was then switched to the other agent at approximately the same dose rate, titrating the dosage to the same cardiac output, and repeat measurements were made at 20 minutes when again stable. Similar dosages of dopamine (6.2 +/- 1.7 micrograms/kg/min) and dobutamine (6.7 +/- 2.5 micrograms/kg/min) produced equivalent heart rate (103 +/- 19 vs. 102 +/- 13 beats/min, p = NS), cardiac index (2.8 +/- 1.1 vs. 2.9 +/- 1.2 l/min/m2, p = NS), and pulmonary arterial pressure and vascular resistance. Mean systemic arterial pressure was significantly lower with dobutamine (59 +/- 5 vs. 67 +/- 7 mmHg, p less than 0.05) as were mean left (14 +/- 5 vs. 18 +/- 6 mmHg, p less than 0.0001) and right (9 +/- 2 vs. 11 +/- 2 mmHg, p less than 0.05) arterial pressures.(ABSTRACT TRUNCATED AT 250 WORDS)