Renal replacement therapy-when, how, how long?

When to start renal replacement therapy (RRT) is often the decisive measure in the management of patients with severe acute kidney injury (AKI). Based on recent studies a watchful waiting approach seems to be feasible in many cases even in patients with stage III AKI; however, RRT should be initiated immediately in cases of overt life-threatening volume overload, disturbances of electrolyte and/or acid-base balance. Patients who will eventually need RTT during the clinical course could possibly benefit from early initiation of RTT; however, such patients are hard to identify as suitable instruments are not available. Currently, evaluation of the broader clinical context by an experienced intensive care physician guides the decision about when to start RRT. Continuous and intermittent techniques of RTT should be used complementarily. In continuous treatment there is no evidence of a benefit of the convective part of RRT, so that convective and diffusive techniques must be considered as comparable. The recommended "dose" in continuous RRT is 20-25 ml/kg pro Stunde. Higher doses are not recommended even in patients with septic shock because of a higher risk for undesirable side effects of RRT. Regional citrate anticoagulation (RCA) provides better filter run times and less bleeding risk compared to conventional systemic anticoagulation during continuous RRT; however, there is no evidence for a better survival with RCA. When renal functional recovery after AKI allows control of volume, electrolyte and acid-base balance and the detoxification of uremicmetabolic products, RRT should be discontinued. Over the years many potential biomarkers of renal injury and clinical panels have been identified, which enable an early diagnosis and prognosis of the course of AKI, including indications for the need for RRT.