Quantitative effects of low-dose dopamine on urine output in oliguric surgical intensive care unit patients

Abstract

Objective: To quantify the magnitude and time course of the effect of low-dose dopamine (2.5 micrograms/kg/min) infusions on urine output in oliguric patients.

Design: A prospective, clinical study.

Setting: A surgical intensive care unit (ICU) at a university hospital.

Patients: A total of 19 surgical ICU patients with oliguria (< 0.5 mL/kg/hr) after resuscitation to pulmonary artery occlusion pressures > 10 mm Hg, mean arterial pressures > 65 mm Hg, and cardiac index > 2 L/min/m2. Patients with acute renal failure and those patients receiving diuretics were excluded.

Measurements and main results: Urine output was monitored hourly before and after dopamine was instituted for the treatment of oliguria. Spot urine electrolyte determinations and urine specific gravity measurements were obtained. Patients with urine output improvement (> 50% increase) had dopamine stopped after 4 hrs. If urine output decreased to < 0.5 mL/kg/hr, dopamine was resumed. There were no dopamine-induced changes in heart rate, pulmonary artery occlusion pressure, mean arterial 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 exceeded 1.0 mL/kg/hr in 84% of patients. After dopamine was stopped, urine output decreased to < 0.5 mL/kg/hr in 79% of patients and responded to resumption of dopamine in 100% of patients. There were no significant changes in urine sodium concentration or specific gravity.

Conclusions: Low-dose dopamine infusion alone produces a drug-dependent increase in urine output in oliguric, euvolemic ICU patients. Maximal effect is temporally variable.