Chapter 64 Renal Failure
Acute
PATHOPHYSIOLOGY
Acute renal failure (ARF) is the abrupt reduction or cessation of renal function secondary to a sudden loss of functioning nephrons. The rapid loss of renal function leads to a reduction in the glomerular filtration rate (GFR). This causes a build-up of urea and creatinine, fluid-electrolyte imbalances, and other related problems. ARF occurs from a variety of causes (see Box 64-1). These causes are grouped into three categories: prerenal (hypoperfusion), intrarenal (intrinsic renal), and postrenal(obstructive). Acute prerenal failure results from decreased blood flow to the kidneys. Subsequent renal hypoxia causes cellular edema and injury and cell death. Acute intrarenal failure results from injury to the kidney tissue. Acute postrenal failure results from urinary outflow obstruction. ARF occurs suddenly and entails multiple problems and potentially threatening complications. Children with ARF and their families need ongoing support and education. ARF outcomes range from complete recovery to the development of chronic renal failure.
Box 64-1 Causes of Acute Renal Failure
Prerenal (Hypoperfusion)
• Severe hypovolemia and/or severe hypotension: severe dehydration, shock, cardiac failure, severe vascular fluid shifts and/or third-space losses, hemorrhage
• Pharmacologic effects: renal vasoconstriction, severe hypotension, impaired renal autoregulatory response owing to blocked prostaglandin production (nonsteroidal antiinflammatory drugs, cyclooxygenase inhibitors and angiotensin-converting enzymes)
Intrarenal (Intrinsic)
• Small renal vessels: embolism, hemolytic-uremic syndrome (HUS), thrombotic thrombocytopenic purpura, severe hypertension
• Glomerulus: glomerulonephritis, renal vasculitis
• Tubules: acute tubular necrosis from ischemia (sepsis, hypovolemia, hypotension) or toxins; obstruction from uric acid, calcium oxylate or other compounds
• Interstitium: interstitial nephritis, pyelonephritis, infiltration from tumors or other agents
• Congenital kidney abnormalities: polycystic kidney disease, renal dysplasia, bilateral agenisis, glomerular maturation arrest
• Nephrotoxic agents: chemotherapy, cyclosporine, antibiotics (aminoglycosides, penicillins, cephalosporins, sulfonamides, amphotericin), radiographic contrast dye, heavy metals (mercury), myoglobin, organic solvents, pesticides, arsenic (rat poisoning)
INCIDENCE
1. Incidence and prognosis vary according to age, etiology, associated problems, underlying condition, geographic location, and type of treatment.
2. ARF in infants and children is most frequently caused by prerenal failure (hypoperfusion).
3. ARF is a common complication of critical illness. ARF in critically ill patients has been associated with high mortality (>60%). When ARF is combined with multisystem organ failure, the risk of death is even higher.
CLINICAL MANIFESTATIONS
The clinical presentation of ARF will vary based on the underlying cause.
1. Azotemia is the cardinal sign for ARF, regardless of type. (In critically ill children, the precipitating disease process frequently overshadows clinical manifestations of ARF.)
2. Oliguria with fluid retention and edema
6. Central nervous system dysfunction
8. Decreased urine output is frequently associated with ARF; patients with nonoliguric ARF may have normal or increased urine output.
COMPLICATIONS
1. Fluid balance complications: fluid overload, intravascular volume depletion from third-space losses, pulmonary edema, ascites causing respiratory difficulty
2. Electrolyte imbalances—arrhythmias, cardiac arrest, seizures
3. Cardiovascular: congestive heart failure, hypertension, hypotension, arrhythmias, shock, cardiac arrest
4. Respiratory: tachypnea, pulmonary edema, respiratory failure
5. Neurologic: altered level of consciousness, seizures, intracranial bleeding in neonates
6. Hematologic: anemia due to lack of erythropoietin and decreased blood cell production, bleeding (coagulopathies)
7. Infection can occur since the child is immunocompromised
8. Skin breakdown due to poor healing, malnutrition, pruritus
9. Malnutrition from decreased caloric intake, nausea, vomiting, diarrhea, and protein loss
LABORATORY AND DIAGNOSTIC TESTS
Refer to Appendix D for normal values and/or ranges of laboratory and diagnostic tests.
1. Blood tests: chemistry panel provides information related to levels of blood urea nitrogen (BUN), creatinine, serum electrolytes (potassium, sodium, calcium, magnesium, and phosphorus), glucose, and protein (albumen, total protein), as well as acid-base status (bicarbonate). Complete blood count (CBC) provides data related to the hematocrit, hemoglobin, and platelets. Serum blood gas results (arterial, capillary, or venous) provide data related to blood pH and acid-base status. Common alterations of these laboratory results in patients with ARF are listed as follows:
2. Urine tests: urinalysis—to test for blood in the urine and for excretion of electrolytes; quantification of excreted electrolytes provides information related to renal function.
3. Electrocardiogram (ECG)—to assess changes associated with electrolyte imbalance and heart failure
4. Chest and abdominal x-ray studies—to assess for fluid retention, kidney presence and size
5. Ultrasonography—to determine kidney size, urinary tract obstruction, tumors, cysts
6. Renal Doppler blood flow—to determine if renal vascular disease is present
7. Radiographic imaging (intravenous pylography, radionuclide studies, renal arteriogram)—to examine for renal obstruction, blood flow, kidney structures, renal function
MEDICAL MANAGEMENT
Evaluation of the child’s history, symptoms, and laboratory results assists with determining the cause of ARF and the appropriate treatment approach. One of the highest priorities is to stabilize the fluid and electrolyte status. This is done through strict intake-and-output monitoring and setting fluid limits as appropriate for each child’s fluid needs. At times, fluid bolus and/or additional maintenance fluids may be needed to ensure adequate circulating volume to prevent further renal damage related to hypoperfusion. This should be done carefully to prevent overhydration. Electrolyte balance is managed by carefully monitoring serum levels, ensuring appropriate hydration, limiting potassium and phosphorus as needed, and infusing deficient electrolytes as appropriate. Severe hyperkalemia (>6 to 7 mEq/L) is a medical emergency requiring immediate action. This is done through rectal or nasogastric (NG) administration of sodium polystyrene sulfonate (kayaxalate), inhaled beta agonists, hemodialysis, and/or intravenous insulin and glucose, sodium bicarbonate, and/or calcium. Hyperphosphatemia can be treated with phosphate binders.
Other important aspects of managing ARF include supporting cardiovascular function (avoid fluid overload, treat hypertension, and avoid hypotension), supporting respiratory function (providing oxygen and/or mechanical ventilation as needed), treating anemia (administering blood products and/or other medications for anemia and controlling bleeding), preventing infection (administering antibiotics and minimizing invasive procedures when possible), and supporting nutrition (administering parenteral nutrition and/or enteral feeds and ordering a low salt diet.
NURSING ASSESSMENT
1. Assess for signs and symptoms of fluid volume excess.
2. Assess for signs of electrolyte imbalance. Frequently monitor serum electrolytes for range values.
3. Assess for signs of uremia.
4. Assess for signs of decreased cardiovascular functioning (hypotension, hypertension, shock, congestive heart failure, cardiac arrhythmias, fluid volume deficit).
5. Assess for signs of ineffective breathing pattern.
6. Assess for signs of hematologic dysfunction (anemia, bleeding, thrombocytopenia, platelet dysfunction).
7. Assess for signs of infection (fever, increased white blood cell count, septic shock).
8. Assess for signs of failure to thrive (FTT) and malnutrition (lethargy, weakness, poor feeding, decreased appetite, vomiting, failure to gain weight, inadequate caloric intake, loss of developmental milestones).
10. Assess child’s comfort level (refer to Appendix I).
11. Assess child’s level of activity and developmental needs (refer to Appendix B).
12. Assess child and family’s coping response, caregiver roles, knowledge level, and ability to manage the child’s long-term care.
NURSING DIAGNOSES
• Urinary elimination, Impaired
• Fluid volume, Risk for deficient
• Tissue perfusion, Ineffective
• Breathing pattern, Ineffective
• Intracranial adaptive capacity, Decreased
• Nutrition: less than body requirements, Imbalanced
• Skin integrity, Risk for impaired
• Coping, Risk for ineffective
• Development, Risk for delayed
• Caregiver role strain, Risk for
NURSING INTERVENTIONS
1. Monitor and maintain fluid balance.
2. Monitor serum electrolytes and acid-base balance. Implement corrective measures as indicated.
3. Frequently reassess respiratory and cardiovascular status, supportive measures, and airway stabilization as indicated.
4. Monitor neurologic functioning, and promptly report deterioration in status. Promptly respond to seizure activity.
5. Assess for signs of bleeding, and implement bleeding precautions (soft toothbrush, minimize needle sticks, avoid invasive procedures).
6. Monitor for signs of anemia, and implement corrective measures as indicated (blood transfusion, medication); use minimum volumes for blood draws.
7. Assess for signs of infection and implement preventive measures.
8. Assess for signs of malnutrition, and provide nutritional support.
9. Monitor for signs of skin breakdown, and implement corrective measures:
10. Assess child’s comfort level and implement pain control measures (see Appendix I).
11. Provide developmentally appropriate activity while ensuring adequate rest periods (refer to Appendix B).
12. Assess coping responses, and provide therapeutic environment for the child and family.
13. Assess family’s ability to manage their child’s long-term care and provide supportive measures as indicated.
Discharge Planning and Home Care
If ARF has not resolved before discharge, provide child and parents with developmentally appropriate verbal and written instruction regarding home management of the following:
CLIENT OUTCOMES
1. Child’s fluid-electrolyte and acid-base status will be within normal limits.
2. Child will not demonstrate signs and symptoms of complications related to ARF.
3. Child will demonstrate normal growth and development.
4. Child and family will demonstrate sense of mastery in dealing with disease process.
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