Acute oliguria after cardiopulmonary bypass: renal functional improvement with low-dose dopamine infusion.

Hemodynamic and renal function response to low-dose (100 and 200 micrograms/min) dopamine infusion was studied in 15 adult cardiac surgical patients who manifested combined oliguria and left ventricular dysfunction postoperatively. Patients were studied an average of 6.6 h after ICU admission, at normothermia and after 2 consecutive hourly urine output determinations of less than 0.5 ml/kg . h in the presence of a left atrial or pulmonary artery occlusion pressure over 12 mm Hg. Dopamine infusion at 100 micrograms/min produced improvement in creatinine, osmolar and free water clearances (70 +/- 10 to 115 +/- 13, 37 +/- 4 to 93 +/- 16 and --15 +/- 2 to --37 +/- 10 ml/min, respectively), and urinary sodium concentration (15 +/- 5 to 29 +/- 10 mEq/L). Urine flow improved overall from 22 +/- 2 to 54 +/- 9 ml/h; however, in 9 of 15 patients, flow was less than 0.5 ml/kg . h (33 +/- 5 to 50 +/- 6 ml/h). In each of these 9 patients, dopamine infusion at 20 micrograms/min further improved urine flow as well as measured renal function. Plasma renin activity measured in 9 of the 15 patients before and during the 100 micrograms/min dopamine infusion was decreased from 1.95 +/- 0.57 to 0.73 +/- 0.39 ng/ml . h. The hemodynamic effect of both dopamine doses was increased cardiac output coupled with decreased systemic (SVRI) and pulmonary vascular resistance index (PVRI). In these 15 patients, low-dose dopamine infusion produced significant improvement in renal function, with resolution of oliguria in every case, and with no deleterious hemodynamic effect.