Prolonged low-dose dopamine infusion induces a transient improvement in renal function in hemodynamically stable, critically ill patients: A single-blind, prospective, controlled study

Objective: To evaluate the length of the effects of long-term (48 hrs), low-dose dopamine infusion on both renal function and systemic hemodynamic variables in stable nonoliguric critically ill patients. Design: Prospective, single-blind, controlled clinical study. Setting: University hospital, 19-bed multidisciplinary intensive care unit. Patients. Eight hemodynamically stable, critically ill patients with a mild nonoliguric renal impairment (creatinine clearance between 30 and 80 mL/min). Interventions: Each patient consecutively received 4 hrs of placebo, followed by a 3 mu g/kg/min dopamine infusion during 48 hrs, then a new 4-hr placebo period. We measured cardiac output and other hemodynamic variables by using a pulmonary artery catheter. The bladder was emptied to determine urine volume and to collect urine samples. Measurements were performed at six times: after the initial control of 4 hrs of placebo (C1); after 4 hrs (H4), 8 hrs (H8), 24 hrs (H24), and 48 hrs (H48) of dopamine infusion; and after the second control of 4 hrs of placebo (C2). Measurements and Main Results: We saw no significant change in systemic hemodynamic variables with dopamine at all times of infusion. Diuresis, creatinine clearance, and the fractional excretion of sodium (FENa) at C1 and C2 were not different. Urine flow, creatinine clearance, and FENa increased significantly 4 hrs after starting dopamine (for all these changes, p < .01 vs. C1 and C2). The maximum changes were obtained at H8, with an increase of 50% for diuresis, 37% for creatinine clearance, and 85% for FENa (for all these changes, p < .01 vs. C1 and C2). But these effects waned progressively from H24, and both creatinine clearance and FENa at H48 did not differ from control values. Conclusions: In stable critically ill patients, preventive low-dose dopamine increased creatinine clearance, diuresis, and the fractional excretion of sodium without concomitant hemodynamic change. These effects reached a maximum during 8 hrs of dopamine infusion. But despite a slight persistent increase in diuresis, improvement in creatinine clearance and FENa disappeared after 48 hrs. According to these data, it is likely that tolerance develops to dopamine-receptor agonists in critically ill patients at risk of developing acute renal failure.