Initial treatment should focus on correcting fluid and electrolyte balances and uremia while the cause of acute renal failure is being sought. A volume-depleted patient is resuscitated with saline. More often, however, volume overload is present, especially if patients are oliguric or anuric.
Therapy for acute renal failure is directed at treating the underlying cause, correcting fluid, electrolyte and uremic abnormalities, and preventing complications, including nutritional deficiencies. Furosemide (Lasix) administered intravenously every six hours is the initial treatment for volume overload. Depending on whether the patient takes furosemide regularly, the initial dose can be between 20 and 100 mg. If an inadequate response occurs in one hour, the dose is doubled. This process is repeated until adequate urine output is achieved. A continuous furosemide drip may be required. The last resort is ultrafiltration via dialysis.The main electrolyte disturbances in the acute setting are hyperkalemia and acidosis. The aggressiveness of treatment depends on the degree of hyperkalemia and the changes seen on the electrocardiogram. Intravenously administered calcium (10 mL of a 10 percent solution of calcium gluconate) is cardioprotective and temporarily reverses the neuromuscular effects of hyperkalemia.
Potassium can be temporarily shifted into the intracellular compartment using intravenously administered insulin (10 units) and glucose (25 g), inhaled beta agonists or intravenously administered sodium bicarbonate (three ampules in 1 L of 5 percent dextrose).15 Potassium excretion is achieved with sodium polystyrene sulfonate (Kayexalate) and/or diuretics. Sodium polystyrene sulfonate is given orally (25 to 50 g mixed with 100 mL of 20 percent sorbitol) or as an enema (50 g in 50 mL of 70 percent sorbitol and 150 mL of tap water).15 If these measures do not control the potassium level, dialysis should be initiated.
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Acidosis is treated with intravenously or orally administered sodium bicarbonate if the serum bicarbonate level is less than 15 mEq per L (15 mmol per L) or the pH is less than 7.2. The amount of supplemental bicarbonate needed is determined on the basis of the bicarbonate deficit equation: bicarbonate deficit (mEq per L) = 0.5 3 weight (kg) 3 (24 actual serum bicarbonate level).
Sodium bicarbonate ampules are available in two concentrations: 44.6 and 50 mEq per 50 mL. Patients can also be treated orally with sodium bicarbonate tablets (a 300-mg tablet contains 3.6 mEq of sodium bicarbonate), Shohl's solution in 30-mL doses (1 mEq of sodium bicarbonate per mL) or powdered sodium bicarbonate (Arm and Hammer baking soda provides approximately 50 mEq of sodium bicarbonate per rounded teaspoon). Serum bicarbonate levels and pH should be followed closely. Intractable acidosis requires dialysis.
Because acute renal failure is a catabolic state, patients can become nutritionally deficient. Total caloric intake should be 30 to 45 kcal (126 to 189 kJ) per kg per day, most of which should come from a combination of carbohydrates and lipids. In patients who are not receiving dialysis, protein intake should be restricted to 0.6 g per kg per day. Patients who are receiving dialysis should have a protein intake of 1 to 1.5 g per kg per day.16
Finally, all medications should be reviewed, and their dosages should be adjusted based on the glomerular filtration rate and the serum levels of medications.
Between 20 and 60 percent of patients require short-term dialysis, particularly when the BUN exceeds 100 mg per dL (35.7 mmol per L of urea) and the serum creatinine level exceeds the range of 5 to 10 mg per dL (442 to 884 µmol per L). Indications for dialysis include acidosis or electrolyte disturbances that do not respond to pharmacologic therapy, fluid overload that does not respond to diuretics, and uremia. In patients with progressive acute renal failure, urgent consultation with a nephrologist is indicated.
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The Authors
MALAY AGRAWAL, M.D.,
RICHARD SWARTZ, M.D.
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