Renal replacement therapy for acute renal injury: we need better therapy.

Dialytic support of patients with acute kidney injury (AKI) has taken on an important aspect of critical care medicine. Increased morbidity and mortality associated with the AKI syndrome and the lack of great improvement despite the addition of differing dialytic techniques (and intensity) speaks to the need for a re-evaluation of renal support. Continuous therapies have brought greater control of urea, volume, acid/base status and enhanced hemodynamic stability over the traditional intermittent approaches. However, the incremental efficiency achieved by intense dialysis has not improved outcome in patients with AKI. We need to move beyond urea-based decision-making and pursue clinically relevant goal-targeted therapies. The latter will invariably lead to re-evaluation of the timing, intensity and duration of therapy, which traditionally have been mainly solute driven. Whether this will be via specifically designed membrane extracorporeal support or focused drug or cell-based therapies is currently under consideration. Volume determination and variability remain another moving target for therapy. Machine-generated feedback mechanisms responding to specific endpoints or compartmental changes are also under development. Improved diagnostic criteria, especially in septic-induced renal dysfunction, may allow for specific adsorption techniques using a variety of membrane-imbedded substances from activated charcoal to polymyxin B to newer resins. Cascade apheretic techniques have been attempted in specific disease entities to capture a larger group of potential toxins, while nanoporous membranes have been developed to remove a specific sized entity. Bio-artificial systems utilizing functioning cells should help with the recovery of injured cell and cell protection in those yet viable. Simple maneuvers to reduce the cost of delivered therapy, and the development of a more robust severity scoring system to help address the futile use of technology would be of great help. Greater attention to elements lost during intervention which may require supplementation, as well as the development of on-line replacement technology and coagulation friendly systems, will help eliminate much of the current cost of therapy.