From the Journals

Restrictive fluids tied to kidney injury after major abdominal surgery

 

Key clinical point: Compared with a liberal fluid regimen, restricting fluids did not improve disability-free survival and was tied to a significantly increased risk of acute kidney injury among high-risk patients undergoing major abdominal surgery.

Major finding: Rates of acute renal injury were 8.6% with restrictive fluids and 5.0% with liberal fluids.

Study details: International randomized trial of 3,000 patients undergoing major abdominal surgery.

Disclosures: Funders included the Australian National Health and Medical Research Council, the Health Research Council of New Zealand, the Australian and New Zealand College of Anaesthetists, and Monash University, Melbourne. Dr. Myles reported receiving grant support from NHMRC. He had no other disclosures.

Source: Myles PS et al. New Engl J Med. 2018 May 10. doi: 10.1056/NEJMoa1801601

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Trial supports “modestly liberal” fluids

Effective blinding was impossible in this randomized study, wrote Birgitte Brandstrup, PhD, in an accompanying editorial. Differences in fluid volume cause symptoms that clinicians can easily identify, she noted.

She recalled the 1990s, when “surgical patients received so much intravenous saline on the day of surgery that they often gained 4 to 6 kg, and by postoperative day 2 or 3, [and] pulmonary congestion and cardiac arrhythmias were commonplace.” Subsequent trials changed this practice, and patients in the current study received much less fluid than they would have in the old days, she noted.

Nonetheless, the findings indicate “that physiologic principles remain valid: Both hypovolemia and oliguria must be recognized and treated with fluid.” While that does not justify excessive perioperative fluid therapy, “a modestly liberal fluid regimen is safer than a truly restrictive regimen.”

Dr. Brandstrup is with the department of surgery at Holbaek (Denmark) Hospital. She reported having no relevant conflicts of interest. These comments recap her editorial (New Engl J Med. 2018 May 10. doi: 10.1056/NEJMe1805615).


 

FROM THE NEW ENGLAND JOURNAL OF MEDICINE

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.”

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