Quantification of acute renal replacement therapy

The optimal management in patients with acute kidney injury (AKI) remains uncertain and dosing of renal replacement therapy (RRT) remains an important unresolved issue in management of these patients. The concept of dialysis dose though initially tested in patients with end stage kidney disease (ESKD) is now been increasingly being extrapolated in patients with AKI. Urea kinetic modeling the main stay of dialysis dose in ESKD has limited utility in AKI because of ‘non-steady’ state of urea generation, protein catabolism, and volume status in these patients. This is further compounded by differing dialysis techniques employed in these patients. Though various models like equivalent urea clearance, solute reduction index, and the ionic dialysance have been proposed to address these issues, they have their own limitations and have limited clinical experience. Clearance for middle molecules and fluids are also being looked into as independent markers of dialysis adequacy. Few systematic studies have looked at the effect of dialysis dosing on patients outcomes and controversy exists in defining adequate dose of dialysis in these patients. Different study design, patient recruitment, and RRT associated issues could be responsible for these differing results. Thus though the exact dose of RRT in AKI remain undecided the physician should consider various patients characteristics in prescribing these therapies and importantly measure the delivered dose of RRT in each session to accommodate for difference in prescribed and delivered dose.