Discontinuation of renal replacement therapy in critically ill patients with severe acute kidney injury: predictive factors of renal function recovery.

INTRODUCTION: Severe acute kidney injury (AKI-D) is common in critically ill patients and contributes substantially to short- and long-term morbidity and mortality. Acute renal replacement therapy (RRT) is an increasingly widely utilized life-sustaining support strategy for AKI-D patients, providing a bridge to renal recovery in many survivors of AKI. However, key aspects (when and how) of this therapy's appropriate cessation remain unclear. Today, wide variation in clinical practice exists regarding the indication for and the timing of RTT discontinuation, likely due to the poor current evidence base.
METHODS: Few studies have evaluated the process of weaning or ideal markers (clinical factors or parameters that may suggest renal recovery, such as urine output, urine chemistry, and creatinine clearance) to predict sufficient recovery of renal function following AKI and to avoid re-institution of RRT. However, translation of the current evidence to clinical practice is hampered by considerable limitations of the retrospective, post hoc secondary design of cohort studies, small sample sizes, heterogeneity across study populations and illness severity, variations of the thresholds of predictive markers and conflicting results for given markers. Currently, 24-h creatinine clearance greater than 20 ml/min combined with spontaneously decreasing serum creatinine concentrations in the context of fixed RRT and a clinically stable intensive care unit (ICU) patient may be the best predictor of recovery of excretory renal function.
CONCLUSION: The decision regarding the appropriate time to wean acute RRT is complex, integrating numerous clinical variables and renal functional parameters. Cessation of RRT should largely be individualized in critically ill patients. Large randomized multicentre trials are needed to definitively answer the vitally important question of whether inappropriate discontinuation of RRT in ICU patients with AKI-D impacts patient outcomes. Future work should integrate novel kidney damage and repair biomarkers and techniques to measure real-time glomerular filtration rates.