Azotemia control by extracorporeal therapy in patients with acute renal failure

The mortality rate for patients with acute renal failure (ARF) requiring renal replacement therapy remains unacceptably high. The cause of death in these patients has been thought to relate primarily to the nature of the condition that precipitated renal failure. However, recent investigations challenge that notion and suggest that the characteristics of the renal replacement procedure itself may influence outcome. The major considerations for the clinician prescribing renal replacement therapy to the patient with ARF are the therapy mode, the type of membrane used, and the dose of delivered therapy. The first two considerations have been discussed extensively in the medical literature and are reviewed elsewhere in this issue. However, the determination of the amount of delivered therapy, although standard practice in patients with end-stage renal disease, has not been assessed routinely in patients with ARF. Furthermore, the influence on patient outcome of the level of azotemia control achieved by the delivered therapy is unknown. The purpose of this review is to provide some insight into quantifying the amount of renal replacement therapy delivered to patients with ARF treated with either continuous or intermittent therapies. The expected level of azotemia control that can be achieved with each of these therapies is discussed. We suggest that quantification of the amount of delivered therapy and the level of azotemia control are important variables to be obtained and evaluated in future investigations seeking to understand the high mortality rate of patients with ARF.