Restrictive vs. Liberal Fluid Therapy After Abdominal Surgery

Study Questions:

Among high-risk patients undergoing major abdominal surgery, what is the impact of liberal versus restrictive fluid management strategies on 1-year disability free survival and development of postoperative complications?


In the RELIEF multicenter randomized trial, patients were assigned to liberal (reflecting “traditional practice”) versus restrictive (reflecting “net zero balance”) intravenous (IV) fluid management, consisting of crystalloid at 10 versus 5 ml/kg with anesthetic induction, 8 versus 5 ml/kg/hr during surgery, and 1.5 versus 0.8 ml/kg/hr for the remaining 24 hours. The primary outcome was 1-year disability-free survival. Secondary outcomes included acute kidney injury (AKI), surgical site infection (SSI), anastomotic leak, transfusion, duration of hospital stay, and unplanned intensive care unit admission.


A total of 3,000 patients at 47 centers were randomized to restrictive (n = 1,501) or liberal (n = 1,499) management; 24-hour total IV fluid was 6146 ml in the liberal versus 3671 ml in the restrictive groups. Disability-free 1-year survival was 82.3% versus 81.9% in the liberal versus restrictive arms (not significant). Among secondary outcomes, AKI occurred in 5.0% versus 8.6%, and SSI occurred in 13.6% versus 16.5% of patients in the liberal versus restrictive arms.


For patients undergoing high-risk abdominal surgery, the impact of restrictive versus liberal perioperative fluid management on 1-year disability-free survival did not differ significantly. However, the restrictive approach was associated with greater risk of AKI.


This apparent lack of benefit from a restrictive IV fluid management strategy for patients having abdominal surgery contradicts findings from previous smaller trials, which demonstrate fewer complications with restrictive versus liberal fluid management. However, several features of the RELIEF trial distinguish it from earlier trials, including the more moderate “liberal” and more stringent “restrictive” definitions, ongoing postoperative fluid restriction, infrequent early oral intake, and modest 24-hour weight gain in both arms. RELIEF trial findings suggest that patients may receive equivalent or better outcomes when fluid is given in adequate but not excessive quantity, determined by indicators of perfusion and volume status rather than protocols invoking extreme restriction.

Clinical Topics: Prevention

Keywords: Acute Kidney Injury, Anastomotic Leak, Anesthetics, Intravenous, Fluid Therapy, Isotonic Solutions, Length of Stay, Postoperative Care, Primary Prevention, Risk, Surgical Procedures, Operative, Surgical Wound Infection, Water-Electrolyte Balance, Weight Gain

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