Acute renal failure (ARF) has traditionally been defined as the abrupt loss of kidney function that results in the retention of urea and other nitrogenous waste products and in the dysregulation of extracellular volume and electrolytes. In intensive care units (ICUs), acute renal failure often occurs as part of multi-organ failure. The sudden drop in glomerular filtration rate (GFR) results in loss of urine excretion, leading to anuria (i.e. absence of urine production). Renal retention causes levels of urea and creatinine to increase in the blood, followed by metabolic acidosis, electrolyte imbalances (e.g. hyperkalaemia) and other uraemic complications. Consequently, temporary extracorporeal blood purification becomes necessary until recovery of renal function.
Common causes of ARF in ICUs include 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.