Chapter 31 Hemolytic-Uremic Syndrome
PATHOPHYSIOLOGY
Hemolytic-uremic syndrome (HUS) is the leading cause of acute renal failure in infants and young children. HUS is a systemic disease that consists of the following symptomatology: (1) renal failure, (2) hemolytic anemia with fragmented red blood cells and platelets, and (3) thrombocytopenia. Although the exact cause is not known, HUS generally follows an episode of gastroenteritis caused by a strain of Escherichia coli O157:H7, or other enteric pathogens such as Shigella, Salmonella, and Campylobacter. Less commonly, the disease follows an upper respiratory tract infection. The clinical manifestations result from changes in the capillary endothelium caused by the etiologic agent. The endothelial changes result in the following pathologic responses: (1) mechanical trauma to erythrocytes and platelets, which shortens their life span and results in anemia and thrombocytopenia; and (2) decreased renal blood flow and glomerular filtration rate, which results in cortical necrosis and consequent renal failure and acquired hemolytic anemia in infants and children. The severity of the condition varies. The prognosis is related to the efficacy, aggressiveness, and promptness of treatment.
INCIDENCE
1. Most commonly seen in children under the age of 4 years
2. Can occur in geographic outbreaks
3. A seasonal variation exists, with an increased incidence during spring and fall
4. The incidence of hypertension as a long-term complication varies from 10% to 50%.
5. Hemolytic-uremic syndrome affects males and females equally.
CLINICAL MANIFESTATIONS
Prodromal Phase
1. Episodes of diarrhea (may be bloody), vomiting, fever, and abdominal pain
2. In older children, may resemble an upper respiratory tract illness
3. Prodromal symptoms may last 1 to 2 weeks, whereas other symptoms may recur in children who appear to have recovered; severity varies. (See Box 31-1 for three types of clinical manifestation.)
Acute Phase
2. Oliguria or anuria for longer than 1 week, then diuresis
3. Renal failure (metabolic disturbance or acidosis; hypocalcemia or hyperkalemia)
4. Abdominal pain (caused by splenic enlargement or gastrointestinal [GI] involvement)
12. Systemic bleeding manifestations—purpura, petechiae
13. Alteration in neurologic status
14. Anemia associated with uremia
17. Moderate to severe respiratory distress caused by congestive heart failure and circulatory overload
COMPLICATIONS
1. Neurologic—mortality rate in children with neurologic symptoms (seizures, coma) is 90%
2. Disseminated intravascular coagulation—primarily affects vasculature of kidney, nervous system, and GI tract
3. Renal involvement—anemia, acidosis, hypertension, fluid overload, uremia, death
LABORATORY AND DIAGNOSTIC TESTS
1. Renal scan—to assess renal perfusion
2. Renal biopsy—to assess renal involvement
3. Serum protein level—increased
4. Complete blood count—decreased hemoglobin; increased white blood cell count; significant reticulocytosis; reticulocyte count higher than 2%
5. Platelet count—less than 140,000/mm3; remains low for 7 to 14 days
6. Serum albumin level—decreased
7. Arterial blood gas values—decreased pH; acidosis with acute renal failure
8. Electrolyte levels—consistent with renal failure (hyponatremia, hyperkalemia)
9. Tests for hyperuricemia, hypocalcemia, hyperphosphatemia
10. Urinalysis—gross hematuria, proteinuria, casts
11. Blood urea nitrogen, creatinine levels—elevated; reflect severity of renal failure
MEDICAL MANAGEMENT
Early diagnosis and aggressive treatment are the goals. Early intervention with peritoneal dialysis is the most effective treatment for children who have been anuric for 24 hours or who demonstrate oliguria with hypertension and seizures. Supportive care is directed toward vascular support and stabilization, focusing on fluid, electrolyte, and metabolic balances, adequate nutrition, and controlling blood pressure.
Drugs such as corticosteroids, anticoagulants, or antiplatelet agents have not been found to be effective.
NURSING INTERVENTIONS
1. Monitor and maintain fluid and electrolyte balance.
2. Monitor electrolytes and observe for signs of imbalance.
3. Transfuse with blood products as indicated.
4. Observe and report signs and symptoms of impending complications.
5. Monitor for nutritional status; nasogastric feedings or hyperalimentation may be needed.
6. Prepare child and family for peritoneal dialysis or hemodialysis if indicated; indications include the following:
7. Provide information about procedures before they are performed, and reinforce data provided to parents.
Discharge Planning and Home Care
1. Instruct child and family regarding dietary restrictions.
2. Instruct child and family regarding medications.
3. Consult discharge planning team, and educate child and family for home peritoneal dialysis if needed.
4. Instruct child and family regarding signs and symptoms of complications that must be reported.
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Hockenberry MJ, et al. Wong’s nursing care of infants and children, ed 7. St. Louis: Mosby; 2004.
Peacock E, Jacob VW, Fallone SM. Escherichia coli 0157:H7: Etiology, clinical features, complications, treatment. Nephrol Nurs J. 2001;28(5):547.
