Low dose dopamine infusion reduces renal tubular injury following cardiopulmonary bypass surgery

Background: The use of dopamine to protect the kidneys against hypoperfusio n injury remains controversial with little clinical evidence of benefit and increasing concerns regarding safety. In this double-blind, prospective, r andomised study, we investigated the effect of dopamine infusion (2.5 mug/k g/min) on glomerular filtration rate (GFR) and tubular injury in patients u ndergoing routine cardiopulmonary bypass (CPB). Methods: Forty eight patients were randomly assigned to receive intravenous dopamine or saline from induction of anaesthesia until 48 hours post-opera tively. There were no differences in mean age,bypass time or pre-op creatin ine in the 36 patients (33 men) who completed the study. Cr-51-EDTA GFR (ml /min/1.73ml(2)) was measured pre-operatively and on day 5 only. Urinary mar kers of tubular injury (albumin, N-acetyl glucosaminidase, NAG; retinol bin ding protein, RBP) were measured pre-operatively, and on days, 1, 2 and 5. Results: GFR was preserved equally in both groups. All patients demonstrate d significant tubular injury but urinary levels of NAG and RBP were lower i n the dopamine group (41%, p=0.057 and 41%, p=0.007, respectively) on the f irst post-operative day. Conclusion: We conclude that low dose dopamine infusion may reduce renal tu bular injury following CPB in patients with normal or near normal baseline renal function.