Effect of postoperative intravenous loop diuretic on renal function after major surgery

Objective: To determine the effect on renal function of postoperative continuous, intravenous furosemide after major thoraco-abdominal or vascular surgery. Design: Randomized, double-blind, placebo-controlled trial. Setting: Intensive care unit of a referral hospital in Eastern Switzerland. Methods: Furosemide (1 mg/h) or placebo was administered to 121 consecutive patients admitted to the intensive care unit after major abdominal, chest or vascular surgery and continued throughout the intensive care treatment period. Enrollment was performed during a 6 months period. No patient was excluded. Renal function was determined serially by measuring creatinine clearances and plasma creatinine concentrations. Results: Postoperatively, creatinine clearance decreased significantly to 83% (furosemide) and to 81% (placebo group) of the initial value (p = 0.004). This decrease was not affected significantly by furosemide. Retrospective subgroup analysis using stepwise regression also did not show any differences between the groups. Hypokalemia was detected in 36 (furosemide) versus 19% of the blood samples (placebo, p = 0.006). Conclusions: Low-dose intravenous furosemide appears to offer no advantage over placebo in an unselected group of patients with moderate postoperative renal impairment. As no patients with acute renal failure necessitating dialysis were observed during the study period, the effect of furosemide in more severe postoperative renal impairment and the effects of higher doses of loop diuretics remain to be investigated.