Acute renal failure

Acute renal failure (ARF) describes a syndrome characterized by a rapid decline in the ability of the kidney to eliminate waste products, regulate acid–base balance, and manage water homeostasis. ARF is a common clinical problem for the surgical patient, is associated with increased perioperative morbidity and mortality, and presents major diagnostic and therapeutic challenges. A consensus definition for ARF has recently been developed that will hopefully guide future research and work towards improving outcomes.For simplicity, the cause of ARF is divided into probable sources of renal injury (i.e. pre-renal, renal (parenchymal) and post-renal). Several common syndromes predispose to ARF, including major surgery (specifically with cardiopulmonary bypass), rhabdomyolysis, contrast-induced nephropathy and sepsis-associated ARF. The general principles for management of ARF include identification, treatment and/or removal of the precipitant(s) while maintaining physiological homeostasis to allow renal recovery; this may include the early initiation of renal replacement therapy (RRT). There is evidence suggesting that an increased dose of RRT may improve survival. Continuous RRT (CRRT) is possibly the commonest method of RRT in critically ill patients. CRRT may improve rates of renal recovery. Conventional intermittent haemodialysis, which was being used less frequently, is now reappearing in the form of slow low-efficiency dialysis.