The dark side of high-intensity renal replacement therapy of acute kidney injury in critically ill patients.

The impact of intensity or dose of renal replacement therapy (RRT) on outcome of critically ill patients has been a matter of controversy. Most definitions of an adequate dose of acute RRT are based on urea removal, while ignoring other crucial aspects of RRT adequacy in acute kidney injury (AKI). Although some clinical trials have found an improvement in survival with higher doses of intermittent hemodialysis or continuous RRT, results have not been consistent across all studies. The largest trials suggest that there is no additional survival benefit with doses of 35-45 ml/kg/h (CRRT) or daily intermittent hemodialysis. On the other hand, high-intensity treatment may cause life-threatening complications and thereby counteract the benefits of higher small-solute clearance. One important area for future investigations is the need to characterize the potential harm of high-dose RRT for AKI in critically ill patients.