Renal replacement therapy in the ICU: intermittent hemodialysis, sustained low-efficiency dialysis or continuous renal replacement therapy?

Purpose of review Severe acute kidney injury in the ICU setting often requires renal replacement therapy (RRT). Intermittent hemodialysis (IHD), hybrid forms of RRT such as sustained low-efficiency dialysis (SLED), as well as continuous renal replacement therapy (CRRT) are the three common modalities of extracorporeal RRT used in the adult ICU setting in developed countries. This review summarizes recently published data regarding comparisons of these three RRT modalities on clinical outcomes (e.g., mortality and recovery of renal function) in severe acute kidney injury (AKI) patients. Recent findings There is still controversy on the superiority of one RRT modality over another in terms of clinical outcomes in patients with AKI in ICU. Although there is increasing acceptance that CRRT should be used in hemodynamic unstable patients, its survival advantages over IHD remains unproven because of inadequate evidence from suitably powered randomized controlled trials (RCTs). Moreover, CRRT does not show superiority to intermittent renal replacement therapy (IRRT) in hemodynamic stable patients. Although patients receiving sustained low-efficiency dialysis appear to have lower mortality than CRRT, its survival benefit is largely derived from observational studies and is confounded by selection bias. Current literature supports no differences in mortality among the three RRT modalities. However, the effect of choice of RRT modality on short-term and long-term renal outcomes need further studies, especially larger RCTs and longer duration of follow-up. There is lack of solid evidence showing superiority of any mode of RRT in patients with severe AKI in terms of patient survival. However, based on observational data, IHD treatment of AKI may delay renal recovery. Patients' hemodynamic status, coexisting medical conditions, local expertise, and availability of staff and resources as well as potential effect on long-term renal outcomes should be taken into consideration when selecting modalities of RRT for adult ICU patients.