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Acute Renal Failure

The kidneys function to "clean" blood of normal toxic byproducts of human metabolism. Critically ill patients, especially those with sepsis syndrome, underlying diabetes mellitus, exposure to kidney toxic medications or contrast dye, are at risk for developing acute renal (kidney) insufficiency or it's more severe counterpart, acute renal failure (ARF).

When mild, acute renal insufficiency is usually first recognized by elevation of the renal function blood tests BUN (blood urea nitrogen) and creatinine. In the early, mild stage, acute renal insufficiency may be associated with no symptoms. As acute renal insufficiency progresses, the urinary output may remain normal (termed non-oliguric), decreased (termed oliguric) or become negligible (termed anuric). In its most severe form, renal insufficiency progresses to ARF. Patients with ARF may develop congestion of the lungs with fluid, generalized body swelling (edema), and severe laboratory abnormalities (including low blood sodium level, high blood potassium levels or high blood acid load). Symptoms may include shortness of breath, loss of appetite, lethargy, altered sensorium, nausea, vomiting, and generalized itchiness.

Treatment of ARF is largely supportive; the underling disease process is treated and offending medications are held (if possible). If renal failure is severe, dialysis therapy (also known as renal replacement therapy) may be required. In the setting of ARF, dialysis is usually preferred using the bloodstream (termed hemodialysis) via a temporary hemodialysis catheter placed in a vein of the neck, upper chest or groin area. During dialysis therapy, blood is circulated between the patient and a hemodialysis machine. Using various filters, the hemodialysis machine cleans the patient's blood of accumulated toxins and excess fluid.

Assuming the underlying medical problems resolve, the prognosis of acute renal failure in the intensive care unit setting is generally good, even for patients requiring hemodialysis. A small percentage of ARF patient's who survive their critical illness develop persistent renal failure (termed chronic renal failure.) These patients may continue hemodialysis or may be changed over to peritoneal dialysis (dialysis performed via a catheter in the abdominal cavity).

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