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| Hemolytic Uremic Syndrome Hemolytic Uremic Syndrome (HUS) is a disease of blood clotting within the capillaries, the smallest blood vessels in the body. As red blood cells pass through the clogged capillaries, they are sheared apart and broken. This is called hemolysis and accounts for the first part of the syndrome's name. The other half of the syndrome's name refers to kidney failure in which urea and other waste products build up in the bloodstream because the kidney cannot filter and dispose of them. (urea=a waste chemical + emia= in the blood). While the cause of HUS has not been established with certainty, researchers believe that an abnormal inflammation reaction is stimulated in the blood stream causing platelets (the parts of the blood that form clots) to sludge in small blood vessels and form blood clots where they are not supposed to. This uses up the platelets and causes a shortage of them in the rest of the body. This abnormal reaction may be caused by a yet unidentified chemical that is produced in blood plasma (the fluid or non-cellular part of the bloodstream). Additional Information Source Citation: "Hemolytic-uremic syndrome." Judith Sims. The Gale Encyclopedia of Medicine. Ed. Jacqueline L. longe. 3rd ed. Detroit: Gale, 2006. 5 vals, Definition Hemolytic Uremic Syndrome (HUS) is a rare condition that affects mostly children under the age of 10, but also may affect the elderly as well as persons with other Illnesses. HUS, which most commonly develops after a severe bowel infection with certain toxic strains of a bacteria, is characterized by destruction of red blood cells, damage to the lining of blood vessel wails, and in severe cases, kidney failure. Description Most cases of HUS occur after an Infection in the digestive system that has been caused by toxin-producing strains of the bacterium EscherIchIa coff . About 75% of HUS cases in the United States are caused by the strain referred to as E. coli 0157:H7, which is found in the Intestinal tract of cattle, while the remaining cases are caused by non-0157 strains. Some children Infected with E. coli 0157:H7 will develop HUS. HUS also can follow respiratory Infection episodes in young children. In the United States, there are about 20,000 Infections and 250 deaths annually that are caused by E. call 0157:H7. HUS has also been known to occur In persons using drugs such as oral contraceptives, Immunosuppressors, and antlneoplastlcs, and in women during the postpartum period. E. coli. 0157:H7, first identified in 1982, and Isolated with increasing frequency since then, is found in contaminated foods such as meat, dairy products, and juices. Infection with E. coli. 0157:H7 causes severe gastroenteritis, which can include abdominal pain, vomiting, and bloody diarrhea. For most children, the vomiting and diarrhea stop within two to three days. However, about 5 to 10% of the children will develop HUS and will become pale, tired, and Irritable. Toxins produced by the bacteria enter the blood stream, where they destroy red blood cells and platelets, which contribute to the clotting of blood. The damaged red blood cells and platelets clog tiny blood vessels in the kidneys, or form lesions to occur in the kidneys, making it difficult for the kidneys to remove wastes and extra fluid from the body, resulting in hypertension, fluid accumulation, and reduced production of urine. Causes and symptoms The most common way an E. coli 0157:H7 infection s contracted is through the consumption of undercooked ground beef (e.g., eating hamburgers that are still pink Inside). Healthy cattle carry E. coli within their Intestines. During the slaughtering process, the meat can become contaminated with the E. call from the Intestines. When contaminated beef is ground up, the E. coli are spread throughout the meat. Additional ways to contract an E. coli infection include drinking contaminated water and unpasteurized milk and juices, eating contaminated fruits and vegetables, and working with cattle. The Infection Is also easily transmitted from an infected person to others in settings such as day care centers and nursing homes when improper sanitary practices are used. Symptoms of an E. call 0157:H7 infection start about seven days after Infection with the bacteria. The first symptom is sudden onset of severe abdominal cramps. After a few hours, watery diarrhea starts, causing loss of fluids and electrolytes (dehydration), which causes the person to feel tired and III. The watery diarrhea lasts for about a day, and then changes to bright red bloody stools, as the infection causes sores to form in the intestines. The bloody diarrhea lasts for two to five days, with as many as ten bowel movements a day. Additional symptoms may include nausea and vomiting, without a fever, or with only a mild fever. After about five to ten days, HUS can develop, which is characterized by paleness, irritability, and fatigue, as well as reduced urine production. Diagnosis The diagnosis of an E. coli infection is made through a stool culture. The culture must be taken within the first 4B hours after the start of the bloody diarrhea. If a positive culture is obtained, the patient should be monitored For the development of HUS, with treatment Initiated as required. Children should not go to day care until they have had two negative stool cultures. Older people in nursing homes should stay in bed until two stool cultures are negative. Treatment Treatment of HUS is supportive, with particular attention to management of fluids and electrolytes. Treatment generally is provided in a hospital setting. Blood transfusions may be required. In about 50% of the cases, short term replacement of kidney function is required in the form of dialysis. Most patients will recover kidney function and be able to discontinue dialysis. Some studies have shown that the use of antibiotics and anti motility agents during an E. call Infection may worsen the course of the infection and should be avoided. However, other studies have been less definitive. Physicians should stay Informed so that clinical practices matches medical advances on this aspect of treatment. Source Citation – “Hemolytic Uremic Syndrome.” Wong’s Nursing Care of Infants and Children (Eighth Edition) by Marilyn J. Hockenberry and David Wilson, pages 1252-1253. Definition Hemolytic Uremic Syndrome (HUS) is an acute renal disease characterized by a triad of manifestations: ARF, hemolytic anemia, and thrombocytopenia (Caprioli, Peng, and Reemuzzi, 2005). HUS occurs primarily in infants and small children between the ages of 6 months and 3 years. It has been recognized predominantly in Caucasians and, although it occurs worldwide, is more prevalent in South Africa, Argentina. and the west coasts of North and South America. HUS represents one of the main causes of ARF in early childhood (Behrman, Kliegman, and Jenson, 2004). Etiology In the majority of cases of HUS no causative agents have been identified, although recent theories implicate generic factors, prostacyclin deficiency, neuraminidase and agglutination, endotoxins (especially Shigella endotoxin), antithrombin III deficiency, deficiency of antioxidants, and reduced platelet aggregation. The appearance of the disease has been associated with Rickettsia organisms; viruses such as coxsackievirus, echovirus, and adenovirus; E. coli; pneumococci; Shigella organisms; and Salmonella organisms and may represent an unusual response to these infections. HUS caused by enteric infection of the E. coli 0157:H7 serotype is most prevalent pathogen in the United States and Europe, with about 70,000 cases and 60 deaths occurring annually (Bell, Griffin, Lozano, and others, 1997; Caprioli, Peng, and Remuzzi, 2005). Occurrences have been traced to undercooked meat, especially ground beef; unpasteurized apple juice; alfalfa sprouts; and public pools. The disease usually follows an acute gastrointestinal or upper respiratory tract infection and tends to occur in scattered outbreaks in small geographic areas. HUS is clinically and pathologically similar, to thrombocytopenic purpura, except for the hypertension associated with HUS. Some authorities have speculated that thrombocytopenic purpura may be the adult version of the HUS of infancy and early childhood. Pathophysiology The primary site of injury appears to be the endothelial lining of the small glomerular arterioles, but other organs and tissues may be involved (e.g., the liver, brain, heart, pancreatic islet cells, and muscles). The endothelium becomes swollen and occluded with the deposition of platelets and fibrin clots (intravascular coagulation). Red blood cells are damaged as they move through the partially occluded blood vessels. These fragmented red blood cells are removed by the spleen, causing acute hemolytic anemia. Fibrinolytic action on the precipitated fibrin causes these fibrin-split products to appear in the serum and urine. The characteristic thrombocytopenia is produced by the platelet aggregation within damaged blood vessels or the damage and removal of platelets. Clinical Manifestations The disease is preceded by a prodromal period during which there is an episode of diarrhea and vomiting. Less often the illness is an upper respiratory tract infection or, occasionally, varicella, measles, or a UTI. The hemolytic process persists for several days to 2 weeks. During this time the child is anorectic, irritable, and lethargic. There is marked and rapid onset of pallor accompanied by hemorrhagic manifestations such as bruising, purpura, or rectal bleeding. Severely affected patients are anuric and often hypertensive. Seizures and stupor suggest central nervous system involvement, and there may be signs of acute heart failure. Mild cases demonstrate anemia, thrombocytopenia, and azoremia; urinary Output may be reduced or increased. Diagnostic Evaluation The triad of anemia, thrombocytopenia, and renal failure is sufficient for diagnosis. Renal involvement is evidenced by proteinuria, hematuria, and urinary casts; blood urea nitrogen and serum creatinine levels are elevated. A low hemoglobin and hemarocritand a high reticulocyte count confirm the hemolytic nature of the anemia. Therapeutic Management In general, treatment is directed toward control of the complications and hematologic manifestations of renal failure (Siegler and Oakes, 2005). The initial supportive measures for most children are those used in managing renal failure: fluid replacement (calculated with great care), treatment of hypertension, and correction of acidosis and electrolyte disorders (Sielger and Oakes, 2005). The most consistently effective treatment is early hemodialysis, PD, or continuous hemofiltration, which is instituted in any child who has been anuric for 24 hours or who demonstrates oliguria with uremia or hypertension and seizures. Blood transfusions with fresh, washed packed cells are administered for severe anemia but are used with caution to prevent circulatory overload from added volume. Once vomiting and diarrhea have resolved, the child is restarted on enteral nutrition. Sometimes parenteral nutrition is required for children with severe, persistent colitis and for those in whom tissue catabolism is marked. There is 'no substantial evidence that heparin, corticosteroids, or fibrinolytic agents are beneficial, and in some instances they may aggravate the condition. The usefulness of plasma infusion for treatment of HUS is currently being studied; it may be useful in selected cases. Prognosis. With prompt treatment the recovery rate is approximately 95%, bur residual renal impairment ranges from 10% to 50% in various areas. Death is usually caused by residual renal impairment or central nervous system injury. Nursing Care Management Nursing care is the same as that provided in ARF and, for children with continued impairment, includes management of chronic disease. Because of the sudden and life-threatening nature of the disorder in a previously well child, parents are often ill prepared for the impact of hospitalization and treatment. Therefore support and understanding are especially important aspects of care. Nursing Alert! To prevent infection from contaminated meat, the internal temperature of the food, such as hamburger, should be at least 74 C (165' F). Cooking the ground beef until no pink color is seen may not be sufficient to kill the bacteria. Therefore a meat thermometer is needed to ensure a safe product. Discourage parents from giving children unpasteurized apple juice and unwashed raw vegetables. Also discourage the use of antimotility drugs for diarrhea. Typical Helpful Links National Kidney Foundation Health Guide Info on MedicineNet.com Definition on MedicineNet.com American Journal of Kidney Disease MyOptumHealth.com About-HUS.com Netdoctor.co.uk MedlinePlus WIKIPEDIA |
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