For critically ill patients with acute kidney injury (AKI) requiring continuous venovenous hemodiafiltration (CVVHDF), faster fluid removal is associated with decreased survival over 90 days.

Raghavan Murugan, MD, MS, of the University of Pittsburgh, and colleagues performed a secondary analysis of the RENAL trial (Randomized Evaluation of Normal vs Augmented Level of Renal Replacement Therapy) including 1434 intensive care patients with AKI treated with CVVHDF (mean age 67 years; 64% male). According to results published in JAMA Network Open, a net ultrafiltration (NUF) rate greater than 1.75 mL/kg/h was associated with lower survival from day 7 to day 90, compared with a NUF rate less than 1.01 mL/kg/h. The odds of dying were 66% higher from day 27 to 90 for patients receiving rapid fluid removal. For every 0.5 mL/kg/h increase in fluid removal their death risk increased 5% to 13% over 90 days.

Several studies of outpatients with end-stage renal disease receiving hemodialysis have yielded similar results.

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“We want to get this excess fluid out of our patients before it causes damage but, in removing it, we’re actually causing a controlled loss of fluid that can sometimes cause stress on the heart and lead to dangerously low blood pressure,” Dr Murugan stated in a university news release. “So the question—how rapidly to remove fluid?—has been asked in the critical care community for many years, but there’s been no good answer.”

A future randomized controlled trial of faster vs slower ultrafiltration is still needed, according to Dr Murugan and the team. In certain cases, such as imminent heart failure, a more rapid removal of fluid might be necessary to prevent sudden death. In the current study, clinicians determined the ultrafiltration rate.

“You have to balance the pros and the cons, and decide how fast to remove fluid based on your patient’s clinical condition,” Dr Murugan stated. “But in a patient where I can’t find an immediate need to get fluid out quickly, I’ll be removing fluid at a slower rate until we get definitive results and guidance from a clinical trial.”


Murugan R, Kerti SJ, Chang CCH, et al. Association of net ultrafiltration rate with mortality among critically ill adults with acute kidney injury receiving continuous venovenous hemodiafiltration: A secondary analysis of the randomized evaluation of normal vs augmented level (RENAL) of renal replacement therapy trial. JAMA Netw. 2019;2(6):e195418. doi:10.1001/jamanetworkopen.2019.5418

Rapidly removing fluid from critically ill patients in kidney failure linked to increased risk of death (news release). Health Sciences at the University of Pittsburgh; June 4, 2019. Pittsburgh, PA.