Renal Failure

Treatment of Intrinsic ARF

The main aims of treatment for intrinsic ARF are to resolve the underlying causes and manage the complications.

The specific aim in nephrotoxic ARF is the elimination of toxins. In ischemic ARF the main aim is to restore blood flow to the kidneys.

Acute glomerulonephritis and vasculitis are generally managed with glucocorticoids and plasmapheresis (plasma exchange).

In allergic interstitial nephritis, if the drug causing the condition is known it is discontinued. To manage the damage which has been caused the patient may be prescribed glucocortoids.

Most frequently, malignant hypertension is treated with ACE inhibitors. ACE inhibitors do not treat the underlying condition but help manage the blood pressure at accepted levels.

Treatment of Complications of Intrinsic ARF

1. Circulatory overload is managed by salt and water restrictions
2. Hyponatremia (low sodium level) in blood is managed with water restriction
3. High level of potassium in the blood (hyperkalemia) is managed with dialysis, K+ restriction, and administration of Na bicarbonate
4. Metabolic acidosis is managed with dialysis, dietary protein restriction and administration of sodium bicarbonate
5. Hyperphosphatemia is managed by dietary restriction of phosphates
6. Hypocalcemia is managed by the administration of calcium carbonate and calcium gluconate
7. Hypermagnesemia is managed by the discontinuation of magnesium-containing antacids. Maalox is a classical example.

Common Indications for commencement of dialysis:

1. Hyperkalemia: High levels of potassium are not compatible with life. Normal K is 3.5 to 4.5 mmols per liter. Hence dialysis is indicated.
2. Circulatory overload occurs when the kidneys are unable to excrete the excess of consumed or metabolically produced water. When the kidneys become nonresponsive to diuretic treatment then dialysis is indicated.
3. Severe acidosis, as defined above, which is nonresponsive to other treatments
4. Severe uremia is not compatible with life. Hence dialysis is indicated.

Long term Prognosis: Mortality rates from Intrinsic Acute Renal Failure depend on the underlying causes of the disease. Approximately 33 percent of patients with this condition (acute toxin induced ARF) die. Approximately 66 percent of patients with intrinsic ARF (which is a complication of major cardiovascular) surgery also die. In conclusion, it is reasonable to state that the outlook is worst when there is oliguria in the patient. Lastly, the outlook for older clients with multiple organ failure is also not encouraging.

POSTRENAL FAILURE (ARF)

Postrenal ARF is the result of an acute obstruction to the outflow of urine from one or both kidneys. The obstruction results in back pressure in the functional units of the kidneys - the nephrons. As we already know the nephrons are the tubular filtering units which produce urine. The excessive back pressure of fluid ultimately causes the nephrons to stop functioning. The amount of renal failure generally is in a linear relationship to the degree and severity of obstruction. Postrenal ARF is prevalent in older patients (mostly males) who have enlarged prostate glands which obstruct to drainage of urine.

Common Causes of Postrenal ARF

There are many causes of postrenal ARF. Some of the common ones are listed below.

1. Urinary bladder outlet obstruction. This is most commonly due to an enlarged prostate gland or bladder stones.
2. Renal calculi in one or both ureters. Ureters are the small drainage tubes which drain urine from the kidneys to the urinary bladder.
3. Grossly distended bladder. Most frequently due to a neurological disorder which results in an inability of the bladder to empty.
4. Sometimes the end channels of the renal nephrons become obstructed. When this happens postrenal ARF is likely to result.
5. Renal injuries: These may be due to motor vehicle or sports injuries
6. Formation of fibrous tissue behind the peritoneum - Retroperitoneal fibrosis. In normal health these fibres lines the abdominal cavity. Their function is to hold the contents of the abdomen in place.

Signs and Symptoms of Postrenal ARF

Flank pain is the most common symptom. However, it varies in severity and location according to the type of obstruction. Other signs and symptoms of postrenal ARF are as follows:

1. Difficult urination
2. Distended bladder
3. Generalized oedema: fluid retention with resultant swelling due to accumulation of fluid in the intracellular spaces
4. Underlying Hypertension or high blood pressure particularly when under treated or not treated
5. Pain in the either flank, lower abdomen, groin, and genitalia
6. Hematuria; presence of frank/ visible blood in the urine

How to diagnose Postrenal ARF

Diagnosis of postrenal ARF should be initiated with a complete physical examination and medical history. Insertion of a foley catheter will reveal a grossly enlarged urinary bladder with a capacity of 2 to 3 liters. For details on how to insert a foley catheter you may visit healthmad.com .

CT or CTT scans of the kidneys can provide useful information about the kidneys, ureters and bladder.

Ultrasounds are the usual tests of choice for diagnosing postrenal ARF. If the kidneys show signs of hydronephros (stretched and dilated renal pelvis), beyond normal dimensions a diagnosis of postrenal ARF can usually be made with certainty.