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 var iables 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/mi n). Interventions: Each patient consecutively received 4 hrs of placebo, follow ed by a 3 mu g/kg/min dopamine infusion during 48 hrs, then a new 4-hr plac ebo period. We measured cardiac output and other hemodynamic variables by u sing a pulmonary artery catheter. The bladder was emptied to determine urin e volume and to collect urine samples. Measurements were performed at six t imes: 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 hem odynamic variables with dopamine at all times of infusion. Diuresis, creati nine clearance, and the fractional excretion of sodium (FENa) at C1 and C2 were not different. Urine flow, creatinine clearance, and FENa increased si gnificantly 4 hrs after starting dopamine (for all these changes, p < .01 v s. 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 progressivel y from H24, and both creatinine clearance and FENa at H48 did not differ fr om control values. Conclusions: In stable critically ill patients, preventive low-dose dopamin e increased creatinine clearance, diuresis, and the fractional excretion of sodium without concomitant hemodynamic change. These effects reached a max imum during 8 hrs of dopamine infusion. But despite a slight persistent inc rease in diuresis, improvement in creatinine clearance and FENa disappeared after 48 hrs. According to these data, it is likely that tolerance develop s to dopamine-receptor agonists in critically ill patients at risk of devel oping acute renal failure.