RENAL SUPPORT IN CRITICALLY ILL PATIENTS - LOW-DOSE DOPAMINE OR LOW-DOSE DOBUTAMINE

Objective: Low-dose dopamine has been used in critically ill patients to minimize renal dysfunction without sufficient data to support its use. The aim of this study was to determine whether low-dose dopamine improves renal function, and whether dobutamine, a nondopaminergic inotrope, improves renal function. Design: Prospective, randomized, double-blind trial. Patients: Twenty-three patients at risk for renal dysfunction were entered into the study. Five patients were later withdrawn. Study data for the remaining 18 patients were: mean age 55 yrs; mean Acute Physiology and Chronic Health Evaluation (APACHE) II score of 18; mean weight 71 kg) The following conditions were present: mechanical ventilation (n = 17 [inverse-ratio ventilation, n = 6]); inotrope administration (n = 11); sepsis (n = 13); and adult respiratory distress syndrome or multiple organ failure syndrome (n = 9). Interventions: The study patients were administered dopamine (200 mu g/min), dobutamine (175 mu g/min), and placebo (5% dextrose) over 5 hrs each in a randomized order. Ventilator settings, fluid management, and preexisting inotropic support were not altered during the study. Measurements and Main Results: Systemic hemodynamic values and indices of renal function (4-hr urine volume, fractional excretion of sodium, and creatinine clearance) were measured during the last 4 hrs of each infusion. Dopamine produced a diuresis (145 +/- 148 mL hr) compared with placebo (90 +/- 44 mL/hr; p < .01) without a change in creatinine clearance. Conversely, dobutamine caused a significant increase in creatinine clearance (97 +/- 54 mL min) compared with placebo (79 +/- 38 mL/min; p < .01), without an increase in urine output. Conclusions: In stable critically ill patients, dopamine acted primarily as a diuretic and did not improve creatinine clearance. Dobutamine improved creatinine clearance without a significant change in urine output.