REstrictive Versus LIberal Rate of Extracorporeal Volume Removal Evaluation in Acute Kidney Injury (RELIEVE-AKI)

  • End date
    Jan 31, 2025
  • participants needed
  • sponsor
    University of Pittsburgh
Updated on 23 October 2022
fluid overload


Critically ill patients with acute kidney injury and fluid overload who are frequently treated by fluid removal during dialysis are at an increased risk of complications and death. Both slower and faster rates of fluid removal may cause injury to the vital organs. This proposed clinical trial will examine the feasibility of restrictive compared with a liberal rate of fluid removal in order to develop effective treatments for fluid overload and to improve the health of critically ill patients.


"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 144 critically ill patients with AKI treated with CKRT in 6 ICUs across two hospital systems. The trial will be conducted at 3 ICUs at University of Pittsburgh Medical Center in Pittsburgh, Pennsylvania, as well as 3 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 five months, all ICUs will continue with a liberal UFnet rate strategy. Every three months thereafter, 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.

Condition Acute Kidney Injury, Fluid Overload, Hypotension, Dialysis; Complications, Critical Illness
Treatment Restrictive UFnet Rate Strategy, Liberal UFnet Rate Strategy
Clinical Study IdentifierNCT05306964
SponsorUniversity of Pittsburgh
Last Modified on23 October 2022


Yes No Not Sure

Inclusion Criteria

Age 18 years or older
Stage 3 acute kidney injury according to the Kidney Disease: Improving Global Outcomes (KDIGO) criteria
Started or intending to start CKRT for volume management
Attending intensivist or nephrologist intending to remove fluid using CKRT for at least 48 hours

Exclusion Criteria

Respiratory distress due to pulmonary edema or fluid overload
Massive volume infusion (i.e., >200 mL/h for >6 hours of continuous infusion)
No intention to remove fluid as determined by attending intensivist or nephrologist
Attending intensivist or nephrologist believes that the protocol will not be followed
Continuous net fluid removal for >24 hours prior to study enrollment
Body mass index >40
Patients on chronic outpatient hemodialysis
Patients with history of, or current admission for kidney transplantation
Patients on comfort measures only orders
Moribund not expected to survive >24 hours
Confirmed pregnancy
Patients treated with extracorporeal membrane oxygenation, ventricular assist device, or intra-aortic balloon pump
Organ donors with neurological determination of death (i.e., brain dead donors)
Drug overdose requiring CKRT for drug clearance
Enrollment in a concurrent interventional clinical trial with direct impact on fluid balance (e.g., >500 mL study drug administration)
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