Restrictive fluids tied to kidney injury after major abdominal surgery

Compared with a liberal fluid regimen, a restrictive perioperative regimen that was aimed at zero balance did not improve disability-free survival among high-risk patients undergoing major abdominal surgery and led to a significantly increased risk of acute kidney injury, researchers reported.

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In an international, randomized trial with 366 median days of follow-up, estimated 1-year rates of disability-free survival were 81.9% with the restrictive intravenous fluid regimen and 82.3% with the liberal regimen (hazard ratio for death or disability, 1.05; P = .61), according to Paul S. Myles, MPH, DSc, and his associates.

Rates of acute renal injury were 8.6% in the restrictive IV fluid group and 5.0% with the liberal fluid therapy (P less than .001), the researchers reported online May 10 in the New England Journal of Medicine.

Guidelines recommend a restrictive intravenous fluid strategy to promote early recovery after major abdominal surgery, noted Dr. Myles of Alfred Hospital in Melbourne and his colleagues. “However, the supporting evidence is limited, and there is concern about impaired organ perfusion.”

Therefore, they randomly assigned, 3,000 patients to receive either the restrictive fluid regimen or a liberal regimen during major abdominal surgery and up to 24 hours after. Median intravenous volume was 3.7 L (interquartile range, 2.9-4.9 L) in the restrictive group and 6.1 L (IQR, 5.0-7.4 L) in the liberal fluid group. All patients were deemed high risk based on their age (at least 70 years) or because they had heart disease, diabetes, kidney disease, or morbid obesity.

Patients who received the restrictive regimen had higher rates of surgical site infection (16.5% vs. 13.6% with liberal fluids; P = .02) and were more likely to receive renal replacement therapy (0.9% vs. 0.3%; P = .048). However, these trends were no longer significant after the researchers controlled for the effects of testing for multiple variables.

“Our findings should not be used to support excessive administration of intravenous fluid,” the researchers cautioned. “Rather, they show that a regimen that includes a modestly liberal administration of fluid is safer than a restrictive regimen.”