Acute renal failure (ARF) is defined as a sudden loss of renal function, whereby the cause is not associated directly with the kidney in most patients in intensive care units (ICU).

The sudden drop in glomerular filtration rate (GFR) results in loss of urine excretion, reaching anuria; enhanced levels of the renal retention solutes urea and creatinine; metabolic acidosis; electrolyte imbalances (e.g. hyperkalaemia); and other uraemic complications.

Consequently, temporary extracorporeal blood purification will be necessary until the recovery of renal function.

Common causes of ARF in ICUs are severe shock, trauma, loss of large quantities of blood, and extended surgery - particularly cardiac and vascular surgery.