Renal replacement therapy in acute kidney injury

About 4% of intensive care unit (ICU) patients worldwide have acute kidney injury (AKI) and require renal replacement therapy (RRT). The choice of modality has expanded from intermittent hemodialysis (IHD) and peritoneal dialysis (PD), where solute clearance is by diffusion, to include continuous renal replacement therapy (CRRT) where convection is the predominant mode of clearance and sustained low-efficiency dialysis (SLED) which involves very slow diffusive clearance without hemodynamic compromise. SLED is considered equivalent to CRRT and is a much less expensive therapy. Early referral to nephrologist improves outcome but the effect of early RRT initiation is still unclear. Fluid overload seems to portend a bad outcome and the benefit of RRT early when there is fluid overload awaits confirmation in a study. The raging debate about dosing of RRT over the past decade seems to be over with the general consensus that increasing RRT dose above a CRRT dose of 20 mL/kg/min may not be beneficial. Heparin anticoagulation is least necessary for IHD. Regional anticoagulation with citrate is possible with need for careful monitoring of pH, ionized calcium and electrolytes. Although largely given up in the west, PD is still an important RRT modality. Various PD techniques are now available for tailoring therapy. PD is the RRT modality of choice in children but CRRT has been increasing in popularity. Newer exciting RRT modalities and other advances are evolving for the treatment of patients with AKI and future trials confirming their clinical utility and safety are awaited.