Acute renal failure (ARF) is defined as a sudden loss of in- and excretory renal function, whereby the cause is not associated with the particular organ '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 until recovery of renal function becomes necessary.

Common causes of ARF in ICUs are severe shock, trauma, loss of large quantities of blood, and extended surgery - particularly cardiac and vascular surgery. In addition, the frequently unavoidable prescription of nephrotoxic substances, such as aminoglycoside antibiotics or contrast media, can induce ARF, particularly in cases where the kidney function is already impaired.