HEMODYNAMIC AND METABOLIC EFFECTS OF DOBUTAMINE IN 18 PATIENTS AFTER OPEN-HEART-SURGERY

Low cardiac output syndrome frequently follows cardiopulmonary bypass (CPB) surgery. In the present study, we used dobutamine to increase cardiac index (CI) and oxygen delivery (ḊO2) in 18 patients after open heart surgery. Using increasing doses of dobutamine up to 10 μg/kg·min-1, we observed statistically significant (p < .01) increases in mean CI (2.50 ± 0.10 to 3.56 ± 0.18 L/min·m2) and in mean heart rate (HR) (83 ± 3 to 105 ± 3 beat/min). Mean systemic vascular resistance index decreased significantly (p < .01) in all patients (2271 ± 101 to 1648 ± 83 dyne·sec/cm5·m2). Pulmonary vascular resistance index did not change in the ten coronary artery bypass graft patients, but decreased significantly (p < .01) in the eight valve replacement patients (561 ± 98 to 421 ± 79 dyne·sec/cm5·m2). Mean ḊO2 increased in all patients, although there was no concomitant increase in oxygen consumption (V̇O2) in four patients. We observed a significant (p < .01) increase in mean V̇O2 in the remaining 14 patients (110 ± 6 to 148 ± 12 ml/min·m2), in spite of significant decreases in PaO2 and increases in right-to-left intrapulmonary shunting. Although increases in HR and ventricular arrhythmias may limit its use, dobutamine increases CI and ḊO2 in patients after CPB. In the present study, dobutamine's varying metabolic effect exemplifies the need for close monitoring of hemodynamic and metabolic variables when using vasoactive drugs in the postoperative period.