Unveiling Current Controversies in Acute Kidney Injury

Acute kidney injury (AKI) is a deadly and incompletely understood disorder in which sudden impairment of kidney function occurs secondary to one or more of a variety of underlying conditions. Mortality associated with AKI is very high and treatment is unsatisfactory. The condition primarily affects acutely ill and injured patients and disproportionably affects the elderly. Many of those that survive have permanent kidney failure and other long-term morbidities, which may include cardiovascular disease and immune dysfunction. While the term 'acute kidney injury' dates back to the early 20th century, when it was used in reference to acute mercury poisoning, it has only recently been applied to describe impaired kidney function in the setting of critical illness. In 2002, during an Acute Dialysis Quality Initiative (ADQI) conference held in Vicenza, AKI was defined using the now widely accepted consensus criteria known as RIFLE (Risk, Injury, Failure, Loss, End-Stage Kidney Disease). AKI replaced the term acute renal failure in part because of the recognition that acute impairment in renal function, even when relatively mild and far less than frank failure, was associated with worse clinical outcomes. Criteria for AKI were therefore set at small changes in serum creatinine or urine output. Thanks to consensus criteria for AKI, we now know that this condition is very common, occurring in as many as two thirds of ICU patients and about 2,100 per million population, and is associated with dramatic reductions in survival -as much as a 3-to 8-fold decrement at hospital discharge compared to controls without AKI.