Effects of dobutamine on haemodynamics and renal function in patients after major vascular surgery

Eight mechanically ventilated patients were studied, before and during a dobutamine infusion the day after major vascular surgery. During infusion of three different doses of dobutamine (2.5, 5, 10 micrograms/kg/min) increases were found in heart rate of 13%, 21% and 47%, systolic blood pressure of 17%, 27% and 35%, and cardiac output of 11%, 22% and 45%, respectively. Right atrial pressure decreased by 20% at the highest dosage. Pulmonary arterial pressure and pulmonary capillary wedge pressure remained unchanged. There were no changes in plasma catecholamine concentrations and plasma renin activity. Fractional potassium excretion decreased by 23%, 33% and 43%, respectively, at the three dosages, while renal blood flow, glomerular filtration rate, urine flow, fractional sodium, chloride, osmolar and free water clearances were unchanged.