Indications and Timing of Continuous Renal Replacement Therapy Application

Renal replacement therapy (RRT) is increasingly utilized to support critically ill patients with severe acute kidney injury (AKI). The clinical dilemma of when to ideally start RRT in these patients has been a longstanding issue that is in need of higher quality evidence to guide clinical practice. When clinicians are confronted with patients with life-threatening complications of AKI, the decision to start RRT is straightforward. However, in the absence of clear indications, the ideal circumstances and timing that balance the perceived benefits and risks of early versus delayed RRT remain uncertain. Survey data have confirmed substantial practice variation in the timing of RRT initiation. Most observational data and small clinical trials have limitations related to confounding by indication, heterogeneity in case-mix and illness severity, and variation in defining timing thresholds for starting RRT. Recently published trials have further added to the clinical uncertainty. This concise review provides an overview of prevailing and evolving evidence on the optimal time to start RRT in critically ill patients with AKI.