Acute renal failure on the intensive care unit

Abstract

Acute renal failure (ARF) occurring on the intensive care unit (ICU) is usually caused by acute tubular necrosis (ATN) and is often associated with multi-organ failure. ICU ARF carries a mortality rate of over 50%, rising to 80% if renal replacement therapy (RRT) is required. ARF independently predicts mortality, and directly contributes to it through 'non-renal' effects such as bleeding and sepsis. 65% of ICU survivors requiring RRT recover renal function. The time course of ATN is usually 7-21 days but is affected both by the duration and severity of the original insult and by the presence or absence of further renal insults. A structured approach to diagnosis helps exclude unusual aetiologies. Key aspects of non-renal replacement management include treatment of the precipitating condition, optimisation of effective circulating volume, attention to drug dosing, avoidance of nephrotoxins and conservative management of ARF complications. Continuous RRT is likely to be the best choice for the most haemodynamically unstable patients, but no renal replacement modality has yet shown superior outcomes compared with others.