Acute renal failure in the surgical patient: initial diagnosis and treatment.

Three categories of acute renal failure have been identified: prerenal, postrenal, and renal. Prerenal failure results from decreased perfusion of the kidney and postrenal failure from obstruction distal to the nephron; renal failure, in the surgical setting, usually represents acute tubular necrosis. A rational approach to the diagnosis of acute renal failure is outlined, and the treatment of acute tubular necrosis is discussed. High-risk factors are identified, and the importance of maintaining intravascular volume to prevent acute renal failure is stressed, since the mortality rate may approach 50% in patients in whom this perioperative complication develops.