Randomised controlled study investigating standard dose continuous renal replacement therapy (CRRT) versus low-dose CRRT in critically ill patients with acute kidney injury (AKI): study protocol for a prospective, randomised, controlled, international, multicentre trial (the 'Ketzerei' trial).

The only supportive therapy for patients with severe acute kidney injury (AKI), a common complication among the critically ill, is dialysis. Based on the literature and current guidelines, continuous renal replacement therapy (CRRT) with a total effluent dose of 20-25 mL/kg/hour and adjustments to ensure such dose is delivered despite down time (eg, due to surgical procedures) is recommended. However, experimental and clinical studies suggest that azotaemia, which can be induced by lowering the effluent dose, may accelerate renal recovery. This clinical study investigates whether a lower effluent dose (10-15 mL/kg/hour) for a maximum of 7 days or until successful (>24 hours) liberation of CRRT in critically ill patients with a dialysis-dependent AKI accelerates renal recovery and reduces time on CRRT compared with guideline-directed standard dose (25-30 mL/kg/hour). The Ketzerei trial is an international, multicentre randomised, controlled trial, designed to investigate if a lower effluent dose (10-15 mL/kg/hour) accelerates renal recovery and reduces the time on CRRT compared with the guideline directed standard effluent dose (25-30 mL/kg/hour). The study aims to enrol 150 critically ill patients with a dialysis-dependent AKI. Eligible patients will be randomised to receive either a standard effluent dose (control group, 25-30 mL/kg/hour) or lower effluent dose (interventional group, 10-15 mL/kg/hour). The primary endpoint is the number of days free from CRRT and alive (from randomisation through day 28). Key secondary endpoints include the number of (serious) adverse events due to potential uremia, the duration of RRT and intensive care unit survival. The Ketzerei trial has been approved by the Ethics Committee of the Chamber of Physicians Westfalen-Lippe (2023-343 f-s), the University of Muenster and subsequently by the corresponding Ethics Committee of the participating sites. Results will be disseminated widely and published in peer-reviewed journals, presented at conferences and will guide patient care and further research. clinicaltrials.gov (NCT06021288).