The effects of a single dose of furosemide on urine flow, fluid balance, and the course of plasma creatinine during cardiac surgery

Introduction

Urine flow rate during cardiac surgery is frequently augmented with diuretics. Recent evidence has shown that a continuous infusion of low dose furosemide - starting before cardiopulmonary bypass (CPB) - has detrimental effects on renal function [1]. It is not known, if this does also apply to a single dose of a diuretic.

Methods

We performed a study to determine the effects of a single dose of furosemide - given immediately before or during CPB - on urine flow (UV), fluid balance and the course of plasma creatinine as a crude measure of renal function in patients subjected to coronary artery bypass grafting (CABG) procedures with CPB. Anesthesia charts from 1/01 to 3/01 were analysed retrospectively in alphabetical order until 24 patients had been selected that fulfilled the criteria: (a) isolated CABG procedure; (b) normal left ventricular function, and (c) no need for inotropes during surgery.

Results

Urine flow (UV), infused fluids and plasma creatinine values P_CREA (mean ± SEM) are given in Table 1. Three patients - all in the diuretics group - received transfusion of packed red cells. Subgroup analysis excluding these patients revealed that relative P_CREA was significantly higher (P < 0.05) after CPB in the diuretics group in comparison with control.

Table 1

Conclusions

These retrospective data suggest that a single dose of furosemide during cardiac surgery does have no beneficial effects on the course of P_CREA and UV but conversely may lead to a greater need of fluids and to a trend to more blood transfusions and a deterioration of renal function.