Design and challenges of the Randomized Evaluation of Normal versus Augmented Level Replacement Therapy (RENAL) Trial: high-dose versus standard-dose hemofiltration in acute renal failure.

BACKGROUND/AIMS The optimal dose of renal replacement therapy (RRT) in acute renal failure (ARF) is uncertain. METHODS The Randomized Evaluation of Normal versus Augmented Level Replacement Therapy Trial tests the hypothesis that higher dose continuous veno-venous hemodiafiltration (CVVHDF) at an effluent rate of 40 ml/kg/h will increase survival compared to CVVHDF at 25 ml/kg/h of effluent dose. RESULTS This trial is currently randomizing critically ill patients in 35 intensive care units in Australia and New Zealand with a planned sample size of 1,500 patients. This trial will be the largest trial ever conducted on acute blood purification in critically ill patients. CONCLUSION A trial of this magnitude and with demanding technical requirements poses design difficulties and challenges in the logistics, conduct, data collection, data analysis and monitoring. Our report will assist in the development of future trials of blood purification in intensive care.