QUANTITATIVE EFFECTS OF LOW-DOSE DOPAMINE ON URINE OUTPUT IN OLIGURICSURGICAL INTENSIVE-CARE UNIT PATIENTS

Objective: To quantify the magnitude and time course of the effect of low-dose dopamine (2.5 mu g/kg/min) infusions on urine output in oligu ric patients. Design: A prospective, clinical study. Setting: A surgic al intensive care unit (ICU) at a university hospital. Patients: A tot al of 19 surgical ICU patients with oliguria (<0.5 mL/kg/hr) after res uscitation to pulmonary artery occlusion pressures >10 mm Hg, mean art erial pressures >65 mm Hg, and cardiac index >2 L/min/m(2). Patients w ith acute renal failure and those patients receiving diuretics were ex cluded. Measurements and Main Results: Urine output was monitored hour ly before and after dopamine was instituted for the treatment of oligu ria. Spot urine electrolyte determinations and urine specific gravity measurements were obtained. Patients with urine output improvement (>5 0% increase) had dopamine stopped after 4 hrs. If urine output decreas ed to <0.5 mL/kg/hr, dopamine was resumed. There were no dopamine-indu ced changes in heart rate, pulmonary artery occlusion pressure, mean a rterial pressure, or cardiac index. Mean urine output increased from 0 .29 to 1.04 mL/kg/hr (p < .001) while patients were receiving dopamine . Time-to-peak response to dopamine was 7 hrs. Urine output increased to >0.5 mL/kg/hr in 95% of patients, doubled in 89% of patients, and e xceeded 1.0 mL/kg/hr in 84% of patients. After dopamine was stopped, u rine output decreased to <0.5 mL/kg/hr in 79% of patients and responde d to resumption of dopamine in 100% of patients. There were no signifi cant changes in urine sodium concentration or specific gravity. Conclu sions: Low-dose dopamine infusion alone produces a drug-dependent incr ease in urine output in oliguric, euvolemic ICU patients. Maximal effe ct is temporally variable.