Acute Kidney (Renal) Failure

What is acute renal failure?

Acute renal failure (ARF) or Acute kidney injury(AKI) is a rapid loss of kidney function.

Its causes are numerous and include low blood volume from any cause, exposure to substances harmful to the kidney, and obstruction of the urinary tract. ARF is diagnosed on the basis of characteristic laboratory findings, such as elevated blood urea nitrogen and creatinine, or inability of the kidneys to produce sufficient amounts of urine.

ARF may lead to a number of complications, including metabolic acidosis, high potassium levels, uremia, changes in body fluid balance, and effects to other organ systems. Management includes supportive care, such as renal replacement therapy(Dialysis), as well as treatment of the underlying disorder.

The kidneys are located on either side of the spine above the waist. The kidneys produce urine by filtering waste products and water from the blood, control the balance of salts/ Electrolytes and water in the body, and help regulate hemostasis or blood pressure. One fully functioning kidney is usually sufficient to perform all of the tasks mentioned above so that the body stays in balance.

  • What do the kidneys do?
  • What are the symptoms?
  • How is acute renal failure diagnosed?
  • How is acute renal failure treated?
  • How does the artificial kidney machine work? 
  • What happens if the kidneys do not recover?

What do the kidneys do ?

‘Acute renal failure’ is the sudden shutdown of both kidneys. The kidneys are no longer able to make urine, rid the body of wastes, or keep a healthy balance of salts such as sodium and potassium.

The kidneys are organs that serve several essential regulatory roles in the human body. The kidneys are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and regulation of blood pressure (via maintaining salt and water balance). They serve the body as a natural filter of the blood, and remove wastes which are diverted to the urinary bladder. In producing urine, the kidneys excrete wastes such as urea and ammonium, and they are also responsible for the re-absorption of water, glucose, and amino acids. The kidneys also produce hormones including calcitriol, erythropoetin, and the enzyme renin.
The kidneys need good blood flow and a decent blood pressure for this to work properly, and ‘acute renal failure’ can occur if the kidneys are not getting enough blood flow secondary to a low blood pressure. People who have been badly burned, have had a big heart attack, have lost a lot of blood, or have a severe infection commonly have reduced blood flow to the kidneys, and thus can suffer from kidney failure.
Failure can also occur when disease, drugs or poisons injure the kidneys. Examples of these include:

  • Complete blockage of the outflow of urine by kidney stones or enlarged prostate
  • Inflammation that affects many organs in the body, including the kidneys (eg Systemic Lupus Erythematosis)
  • Anti-arthritis drugs can occasionally cause kidney damage
  • Post operatively after Abdominal Aortic Aneurysm repair(AAA-repair) due to the length of surgery when the renal arteries  have been “clamped” or closed during surgery

What are the symptoms?

Most symptoms are not specific to kidney failure, and can occur for other reasons. They might include:

  • Drowsiness and fatigue
  • Loss of appetite
  • headache
  • nausea
  • vomiting
  • Confusion
  • Muscle cramps and weakness
  • high Potassium level with irregularities of the heart beat
  • Reduced urine output
  • Swelling of the feet and ankles
  • increased Urea and Creatinine(specific kidney markers in blood results)

How is acute renal failure diagnosed?

The deterioration of renal function may be discovered by a measured decrease in urine output. Often, it is diagnosed on the basis of blood tests for substances normally eliminated by the kidney: urea and creatinine. Both tests have their disadvantages. For instance, it takes about 24 hours for the creatinine level to rise, even if both kidneys have ceased to function.

Sodium and potassium, two electrolytes that are commonly deranged in people with acute kidney injury, are typically measured together with urea and creatinine.

Other blood and urine tests and X-rays or ultrasound tests are then required to understand why the kidneys are failing. The urine can be examined under a microscope, for example, to look for inflammatory cells or bacteria. Ultrasound of the kidneys is frequently used to detect blockage of the urine outflow

How is acute renal failure treated?

If the kidney failure has been caused by a fall in blood flow(hypotension) to the kidneys, then the most important thing is treatment of the cause for the poor blood flow. Blood flow can be restored with either fluids or in case of low blood pressure with inotropic support. If blood flow can be restored, then otherwise healthy kidneys will start working again over a period of days to weeks.

Monitoring of renal function, by serial serum creatinine measurements and monitoring of urine output, is routinely performed. In the hospital, insertion of a urinary catheter helps monitor urine output and relieves possible bladder outlet obstruction, such as with an enlarged prostate.

In the short term, a diuretic drug called Frusemide or Lasix can be given in order to improve Urine Output.
If a disease, such as ‘glomerulonephritis’, has directly affected the kidneys then that disease needs to be treated before the kidney function can start to improve. This is usually treated with Antibiotics.
If the kidneys are failing completely, then treatment with an artificial kidney machine/ Haemodialysis machine is essential and life-saving, while treatment for the underlying condition is undertaken. The treatment is called ‘dialysis’.

How does the artificial kidney machine work?

A vascular catheter is placed into one of your loved ones veins to transport the Patient’s blood to-and-from the kidney machine. Often one of the large veins in the groin is used, but the vascular catheter can also be placed in your loved ones shoulder or neck. The Dialysis machine is essentially taking over the function of the kidneys and all the toxins, wastes, salts, and electrolytes are removed and the clean blood returns to the Patient. Sometimes drugs (such as heparin or Protamine) are given to prevent the Patient’s blood clotting inside the Dialysis machine.

please find more information about Dialysis here

What happens if the kidneys do not recover?

If the kidneys are rsponding well to the treatment, there is a fairly high likelihood that they will fully recover. This can take sometimes weeks or months.

Sometimes Acute Renal Failure develops into permanent or Chronic Renal Failure. Depending on a Patient’s age, either long-term Dialysis or kidney transplant can become necessary.

Australian Kidney Foundation http://www.kidney.org.au/

USA Kidney Foundation http://www.kidney.org/

UK National Kdney Federation http://www.kidney.org.uk/

Any Questions?

Of course, if you have any questions or concerns, please discuss them with the ICU nurses and doctors.

All Intensive Care interventions and procedures carry a degree of potential risk even when performed by skilled and experienced staff. Please discuss these issues with the medical and nursing staff who are caring for your loved one.

The information contained on this page is general in nature and therefore cannot reflect individual Patient variation. It is meant as a back up to specific information which will be discussed with you by the Doctors and Nurses caring for your loved one. INTENSIVE CARE HOTLINE attests to the accuracy of the information contained here BUT takes no responsibility for how it may apply to an individual Patient. Please refer to the full disclaimer.

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