Acute and Chronic Renal Failure

Acute renal failure (ARF) is the abrupt deterioration of renal function that results in marked reduction of urinary output. The causes of acute renal failure are classified as follows:

• Prerenal: Prerenal ARF is often related to conditions that affect blood flow to the kidneys. Causes include cardiovascular disorders, hypovolemia, septic shock, anaphylactic shock, and obstruction of the renal artery.

• Intrarenal: Intrarenal or intrinsic ARF results from the actual destruction of the renal parenchyma. Nephrotoxic chemicals and ischemic injury damage the renal tubules, making them less functional. Chemicals capable of damaging the renal tubules include antibiotics (aminoglycosides and sulfonamides) diuretics, nonsteroidal anti-inflammatories, and contrast media. Ischemic injury of the renal tubules occurs when the mean arterial blood flow is reduced. Ischemic injuries that can result in intrarenal failure include cardiac arrest and hypovolemic shock.

• Postrenal: Postrenal ARF is caused by obstruction to urinary outflow. Kinking of catheter tubing, urinary infections, renal calculi, and prostatic enlargement are examples of obstructions that can lead to postrenal ARF.