Renal dose dopamine in open heart surgery. Does it protect renal tubular function?

BACKGROUND: This prospective, randomized study assessed the effect of dopamine on renal tubular function in patients who had coronary artery bypass grafting. METHODS: Two groups of patients with normal preoperative renal function were randomly divided into a dopamine group (n=11), who received dopamine in a dose of 2 mg/kg x min, and a control group (n=11), who received no treatment. Dopamine infusion was initiated 24 hours before the operation and was continued for 48 hours postoperatively. Measurements of renal function obtained 2 days before the operation were considered preoperative and were repeated on the 1st, 3rd, and 7th postoperative days. Urinary excretion of b2-Microglobulin (b2-M), considered a sensitive means for diagnosing proximal tubular damage, was measured during the early (day 3) and late (day 7) postoperative period. RESULTS: There were no significant differences respect to the clearances of creatinine, osmotic, and free-water in the dopamine group compared with the control group (p>0.05). Urine microalbumin levels significantly increased on postoperative day 3 in both groups. During the early postoperative period, excretion of urine b2-M was significantly greater in the dopamine group than in the control group (p<0.05). CONCLUSIONS: Consequently, in patients with normal preoperative renal and cardiac function scheduled for elective coronary artery bypass grafting, renal dose dopamine infusion alone may not provide sufficient protection on tubular function and increases renal tubular injury during the early postoperative period.