Restrictive Versus Liberal Rate of Extracorporeal Volume Removal Evaluation in Acute Kidney Injury

"Net ultrafiltration (UFnet)," also known as net fluid removal during kidney replacement therapy, has been used in the treatment of fluid overload among critically ill patients with acute kidney injury (AKI) for more than seven decades. However, the optimal rate of fluid removal (i.e., UFnet rate) remains uncertain, complications such as hypotension and cardiac arrhythmias occur frequently, and more than 40% of patients die. Observational studies in critically ill patients receiving continuous kidney replacement therapy (CKRT) show that UFnet rate has a "J" shaped association with mortality with both slower and faster UFnet rates associated with increased risk of death compared with moderate UFnet rates.

The overall objective of this randomized trial is to establish the feasibility of maintaining patients in the restrictive UFnet rate strategy during treatment with CKRT. The investigator's central hypothesis is that a restrictive UFnet rate strategy embracing a "slow and steady" approach to fluid removal is associated with fewer complications, including cardiac arrhythmias, hypotension, and death, compared with a more liberal "sprint and pause" strategy among critically ill patients.

The trial is a prospective, two-center, unblinded, parallel-group, 2-arm, comparative effectiveness, stepped-wedge cluster-randomized trial among 112 critically ill patients with AKI treated with CKRT in 10 ICUs across two hospital systems. The trial will be conducted at 5 ICUs at University of Pittsburgh Medical Center in Pittsburgh, Pennsylvania, as well as 5 ICUs at Mayo Clinic, Rochester, Minnesota. ICUs will be randomized 1:1 to either a restrictive or a liberal UFnet rate strategy. During the first six months, all ICUs will continue with a liberal UFnet rate strategy. Every two months thereafter or when 10 patients have been enrolled, whichever occurs first, one ICU will be randomized to deploy the restrictive UFnet rate strategy.

In the liberal group, the UFnet rate will be titrated between 2.0-5.0 mL/kg/h and maintained throughout fluid removal. In the restrictive group, the UFnet rate will be titrated between 0.5-1.5 mL/kg/h and maintained throughout fluid removal. The UFnet rates used in both strategies are used in current clinical practice.This feasibility trial will be used to support the rationale and design of a future multicenter phase III randomized trial to examine the effects of alternative UFnet rate strategies on patient-centered clinical outcomes.

Amendment changes- The "Delivered UFnet rates" outcome measure was amended based on a new calculation of effect size when we lowered the sample size from 144 patients to 112 patients in the trial.

The Participant Recruitment Rate Over 21 Months" outcome measure was based on a new sample size estimation when we lowered the sample size from 144 patients to 112 patients in the trial due to slow rate of enrollment in the trial.