Renal Failure

Pre existing atherosclerosis: (Prerenal ARF) Several pre-existing medical conditions such as atherosclerosis (Atheroma / fatty deposits in the arteries, resultant hardening of arteries) reduce blood flow to the kidneys. Reduced blood flow brings about pre renal ARF.

Idiopathic causes: Read the article at med.ualberta.ca

Question: Discuss the causes of ARF in the Australian context.

Signs and Symptoms of ARF: A sign, by definition, is what we as nurses can see in a patient. An example of a sign is ankle oedema. Symptoms are what the patients tell us. An example of a symptom is pain.

A preponderance of patients may have the following signs and symptoms but these are non specific and can be present in other conditions. Accurate history taking and laboratory tests must be done to diagnose ARF.

1. Dizziness: This is related to reduced circulating fluid.
2. Dry mouth: Related to reduction of circulating fluid.
3. Low blood pressure (hypotension): Due to lack of fluid and inability of heart to generate blood pressure which is normal for the patient's age.
4. Rapid heart rate: The tachycardia, increased heart rate, is produced by the heart's attempts to compensate for the reduced circulating volume.
5. Slack but leathery skin: This is the result of dehydration of the tissues of the body. When you pinch a fold of the skin and let go it will maintain it's leathery shape for a while. Normal hydrated skin returns to normal shape the moment it is let go.
6. Thirst: The thirst center in the brain is stimulated by the lack of water in the blood.
7. Weight loss: 70 % of the human body is water. Weight loss will occur when circulating fluid is reduced.

As stated earlier urine output is usually low (oliguria) in patients with prerenal ARF. These patients may also have signs and symptoms of cardiac or hepatic disease.

Complications of ARF

Prerenal ARF causes patients to become critically ill. They are frequently admitted to acute care or intensive care units. Most of these patients have severe infections such as hepatitis or meloidosis. This sepsis results in decreased perfusion. As stated earlier, decreased perfusion leads to cardia, liver and renal failures. To learn more about the signs and symptoms of cardiac failure please visit the web site of The American Heart Association.

The main signs and symptoms of heart failure are:

1. Shortness of breath, technically called dyspnea. This is associated with circulatory overload because the kidneys are unable to get rid of excess circulating fluid.
2. Ankle oedema and pulmonary oedema are common. These are related to fluid retention in the tissues, particularly in dependent areas.
3. Venous distension due to engorgement with excessive fluids.

Signs and Symptoms of hepatic (liver) failure include those listed below. For more information please visit Healthtouch .

Confusion - leads to disorientation - stupor. The underlying patho physiology is of encephalopathy. During this condition the brain becomes more and more confused. This results in behavioral changes which are out of voluntary control of the patient. With time, the patient may go into a coma. Death is likely to follow.

Sweet, ammoniacal odor. Hepatic failure results in the accumulation of ammonia in the patients circulation. The ammoniacal smell is due to this ammonia. Elevated ammonia levels contribute to hepatic encephalopathy but the precise mechanism remains unclear.

Diagnosing ARF: Go to the website of the American Family Physician and read the article on Acute Renal Failure.

1. For the purposes of accurate diagnosis and complete medical history must be taken
2. This must be followed by a physical examination
3. Blood must be sent to the laboratory. If it reveals a high BUN to Cr ratio (BUN:Cr > 20:1), along with abnormal urine chemistry then a diagnosis of ARF may be made.
4. On the basis of the history and physical findings the physician must rule out post renal and intrinsic renal causes of ARF.

Treatment of ARF

There are many interventions to treat and manage Acute Renal Failure. All the interventions are aimed at improving renal perfusion. In many situations this will involve the treatment and management of the underlying condition (s). In general intensive care units the major issues are infection, heart and liver failures. This usually involves treating the infection, heart failure, or liver failure). Intravenous (IV) fluids are administered to most patients to treat dehydration.

Prognosis: In general, patients with prerenal ARF improve dramatically with intravenous fluids. Urine output increases and renal function improves.

INTRINSIC RENAL FAILURE (ARF)

Intrinsic renal failure is renal failure which is not caused by pre renal or post renal factors. In Intrinsic renal failure there is damage and injury with both kidneys. Approximately 40% of all renal failures are due to intrinsic factors. Some of the following are well known causes of intrinsic renal failure.

Vascular diseases - Diseases which affect the health and functioning of blood vessels.

1. Glomerulonephritis and vasculitis: In these conditions the afferent, efferent and other arterioles / blood vessels are inflamed.
2. Renal artery obstruction: The obstruction to the renal artery is the result of atherosclerosis or microscopic arterial thrombosis over a prolonged period of time.
Thrombosis of the Renal vein resulting in obstruction and reduced blood flow.
3. Low blood platelet and red blood cell counts resulting in tissue necrosis.