Restrictive versus Liberal Rate of Extracorporeal Volume Removal Evaluation in Acute Kidney Injury (RELIEVE-AKI): a pilot clinical trial protocol

Introduction Observational studies have linked slower and faster net ultrafiltration (UF NET ) rates during kidney replacement therapy (KRT) with mortality in critically ill patients with acute kidney injury (AKI) and fluid overload. To inform the design of a larger randomised trial of patient-centered outcomes, we conduct a feasibility study to examine restrictive and liberal approaches to UF NET during continuous KRT (CKRT). Methods and analysis This study is an investigator-initiated, unblinded, 2-arm, comparative-effectiveness, stepped-wedged, cluster randomised trial among 112 critically ill patients with AKI treated with CKRT in 10 intensive care units (ICUs) across 2 hospital systems. In the first 6 months, all ICUs started with a liberal UF NET rate strategy. Thereafter, one ICU is randomised to the restrictive UF NET rate strategy every 2 months. In the liberal group, the UF NET rate is maintained between 2.0 and 5.0 mL/kg/hour; in the restrictive group, the UF NET rate is maintained between 0.5 and 1.5 mL/kg/hour. The three coprimary feasibility outcomes are (1) between-group separation in mean delivered UF NET rates; (2) protocol adherence; and (3) patient recruitment rate. Secondary outcomes include daily and cumulative fluid balance, KRT and mechanical ventilation duration, organ failure-free days, ICU and hospital length of stay, hospital mortality and KRT dependence at hospital discharge. Safety endpoints include haemodynamics, electrolyte imbalance, CKRT circuit issues, organ dysfunction related to fluid overload, secondary infections and thrombotic and haematological complications. Ethics and dissemination The University of Pittsburgh Human Research Protection Office approved the study, and an independent Data and Safety Monitoring Board monitors the study. A grant from the United States National Institute of Diabetes and Digestive and Kidney Diseases sponsors the study. The trial results will be submitted for publication in peer-reviewed journals and presented at scientific conferences. Trial registration number This trial has been prospectively registered with clinicaltrials.gov ( NCT05306964 ). Protocol version identifier and date: 1.5; 13 June 2023.