Acute Renal Failure
- Is a sudden decline in renal function, usually marked by increased concentrations of blood urea nitrogen (BUN; azotemia) and creatinine; oliguria (less than 500 ml of urine in 24 hours); hyperkalemia; and sodium retention.
- Acute renal failure are classified into following:
- Prerenal failure – results from conditions that interrupt the renal blood supply; thereby reducing renal perfusion (hypovolemia, shock, hemorrhage, burns impaired cardiac output, diuretic therapy).
- Postrenal failure – results from obstruction of urine flow.
- Intrarenal failure – results from injury to the kidneys themselves (ischemia, toxins, immunologic processes, systemic and vascular disorders).
- The disease progresses through three clinically distinct phase which is oliguric-anuric, diuretic, and recovery, distinguished primarily by changes in urine volume and BUN and creatinine levels.
- Complication of ARF include dysrhythmias, increased susceptibility to infection, electrolyte abnormalities, GI bleeding due to stress ulcers, and multiple organ failure. Untreated ARF can also progress to chronic renal failure, end-stage renal disease, and death from uremia or related causes.
- Oliguric-anuric phase: urine volume less than 400 ml per 24 hours; increased in serum creatinine, urea, uric acid, organic acids, potassium, and magnesium; lasts 3 to 5 days in infants and children, 10 to 14 days in adolescents and adults.
- Diuretic phase: begins when urine output exceeds 500 ml per 24 hours, end when BUN and creatinine levels stop rising; length is availabe.
- Recovery phase: asymptomatic; last several months to 1 year; some scar tissue may remain.
- In prerenal disease: decreased tissue turgor, dryness of mucous membranes, weight loss, flat neck veins, hypotension, tachycardia.
- In postrenal disease: difficulty in voiding, changes in urine flow.
- In Intrarenal disease: presentation varies; usually have edema, may have fever, skin rash.
- Nausea, vomiting, diarrhea, and lethargy may also occur.
- Urinalysis shows proteinuria, hematuria, casts. Urine chemistry distinguishes various forms of ARF(prerenal, postrenal, intrarenal).
- Serum creatinine and BUN levels are elevated; arterial blood gas (ABG) levels, serum electrolytes may be abnormal.
- Renal untrasonography estimates renal size and rules out treatable obstructive uropathy.
Therapeutic and Pharmacologic Interventions:
- Surgical relief of obstruction may be necessary.
- Correction of underlying fluid excesses or deficits.
- Correction and control of biochemical imbalances.
- Restoration and maintenance of blood pressure through I.V. fluids and vasopressors.
- Maintenance of adequate nutrition: Low protein diet with supplemental amino acids and vitamins.
- Initiation of hemodialysis, peritoneal dialysis, or continuous renal replacement therapy for patients with progressive azotemia and other life-threatening complications.
- Monitor 24-hour urine volume to follow clinical course of the disease.
- Monitor BUN, creatinine, and electrolyte.
- Monitor ABG levels as necessary to evaluate acid-base balance.
- Weigh the patient to provide an index of fluid balance.
- Measure blood pressure at various times during the day with patients in supine, sitting, and standing positions.
- Adjust fluid intake to avoid volume overload and dehydration.
- Watch for cardiac dysrhythmias and heart failure from hyperkalemia, electrolyte imbalance, or fluid overload. Have resuscitation equipment available in case of cardiac arrest.
- Watch for urinary tract infection, and remove bladder catheter as soon as possible.
- Employ intensive pulmonary hygiene because incidence of pulmonary edema and infection is high.
- Provide meticulous wound care.
- Offer high-carbohydrate feedings because carbohydrates have a greater protein-sparing power and provide additional calories.
- Institute seizure precautions. Provide padded side rails and have airway and suction equipment at the bedside.
- Encourage and assist the patient to turn and move because drowsiness and lethargy may reduce activity.
- Explain that the patient may experience residual defects in kidney function for a long time after acute illness.
- Encourage the patient to report routine urinalysis and follow-up examinations.
- Recommend resuming activity gradually because muscle weakness will be present from excessive catabolism.