Acute Gastroenteritis

Transcription

1 Acute Gastroenteritis Competency: 1. Know the different processes that produce diarrheal stools in children. 2. Determine the important steps in evaluation of the child with acute gastroenteritis. 3. Understand and be able to apply the appropriate management in children with acute gastroentertitis. References: Cheng, Tina L., MD, MPH. Viral Causes of Diarrhea. Pediatrics in Review: 2002; 23: DeWitt, Thomas, MD. Acute Diarrhea in Children. Pediatrics In Review: 1989; 11: Matson, David O., MD, PhD. Epidemiology, Pathogenesis, Clinical Presentation, and Diagnosis of Viral Gastroenteritis in Children. UpToDate: 2009: Northup, Robert S., MD, and Timothy P. Flanigan, MD. Gastroenteritis. Pediatrics in Review: 1994; 12: Epidemiology: In the United States, attack rates of acute gastroenteritis in children average between 1.3 and 2.3 episodes per year between the ages of 0 and 5 years old. Children who attend day care are three times more likely to suffer from acute gastroenteritis than children who do not attend daycare. Some 220,000 US children under 5 year of age are hospitalized with diarrhea each year. These hospitalizations peak in winter months, due primarily to the rotavirus. Some 500 deaths from diarrhea occur annually in the US, the majority of which are secondary to dehydration, electrolyte abnormalities, shock, and cardiac arrest. All reasons why diarrhea in a young infant deserves adequate time and attention. Pathophysiology: There are four basic processes that produce diarrhea in children: secretory, cytotoxic, osmotic, and dysenteric. Diarrhea may be one or a combination of the above processes. Secretory: due to an enterotoxin produced by an infectious, metabolic, or exogenous toxic agent. The enterotoxin stimulates secretion of fluid and electrolytes from the mucosal crypt cells (the principal secretory cells of the small bowel). o Examples: E. coli, Vibrio cholerae, C. difficile, C. perfringens, Aeromonas hydrophilia, Staph. aureus, Vibrio parahaemolyticus, Bacillus cereus, Shigella, Salmonella, Yersinia enterocolitica, Giardia lamblia, Neuroblastoma. Cytotoxic: characterized by destruction of the mucosal cells of the villi of the small bowel, most commonly by an infectious virus. There is an increase in the secretory process and a marked decrease in the absorptive function of the small bowel. o Examples: Rotavirus, Norwalk agent, Cryptosporidium, E. coli. Osmotic: most commonly seen in malabsorption syndromes (e.g., lactose intolerance). If the malabsorbed substance has a high enough concentration to be osmotically active, there is a net flux of water into the lumen of the intestine resulting in loose stools. o Examples: Lactose, Sorbitol. Dysenteric: inflammation of the mucosa and submucosa of the terminal ileum and the large bowel secondary to invasion by a bacterial agent, causing edema, mucosal bleeding, and leukocytic infiltration. Etiology: o Examples: Campylobacter fetus, C. difficile, Salmonella, Shigella, Yersinia enterocolitica, Enamoeba histolytica. Vad är skillnaden mellan en radiolog, röntgen Tekniker, och X-ray-tekniker?

2 Gastroenteritis in children is caused by viral, bacterial, and parasitic organisms (viral and bacterial more likely). Oral ingestion is the primary route of infection, however rotavirus appears to be transmitted by respiratory or mucous membrane contact as well. For most diarrheas, however, determination of the specific etiology is unimportant because the illness is usually short and self limited and will respond to fluid and feeding therapies without the use of antibiotics. It is impossible to distinguish clinically between diarrheas caused by the various viruses. All of the viruses produce water diarrhea often accompanied by vomiting and fever. They are also usually not associated with blood or leukocytes in the stool. Rotavirus is the predominant agent and is the single most important cause of dehydrating diarrhea in both developed and developing countries. Rotavirus infections, causing severe diarrhea, cause of to 70% of the cases requiring hospitalization in children under 2 years of age. Rotavirus infection has a distinct seasonal incidence, occurring in the fall in southwest United States and occurring in the late winter and spring in the northeast United States. Rotavirus diarrhea occurs most frequently in children between the ages of 3 and 15 months. Evaulation of the patient: History and Physical Exam: 1. Assessing a child s state of hydration and likely etiology of diarrhea: a. History: i. Amount of oral intake ii. Frequency and volume of stools: small bowel processes (most likely viral etiology) are more likely to produce large volume, watery stools that are relatively infrequent. Large bowel processes (usually secondary to a bacterial etiology) are more likely to produce frequent, less watery stools. iii. Blood in stool: highly suggestive of a bacterial etiology (in the younger infant (less than 6 months of age) however, blood in the stools is more commonly associated with cow s milk intolerance or anal fissures). iv. History of vomiting: the timing of the onset of vomiting can aid in differentiating a small vs. large bowel process. Small bowel processes, most commonly associated with viruses, cause delayed gastric emptying and luminal distention which often induces vomiting before the onset of diarrhea. v. Frequency of urination vi. Fever? vii. Recent antibiotic use viii. Exposure to daycare or other children or adults with a diarrheal illness ix. Recent travel x. Ingestion of certain foods xi. History of Lactose intolerance xii. Family history of inflammatory bowel disease (if diarrhea is bloody and persistant) xiii. Immunocompromised patient b. Physical Exam: i. General appearance ii. Weight iii. Mental status (e.g., irritability, apathy, or lethargy) iv. Mucous Membranes (e.g., moist or dry) v. Anterior fontanelle (e.g., sunken) vi. Eyes (e.g., sunken eyes, decreased tears) vii. Skin hydration and turgor viii. Temperature, blood pressure, pulse

3 ix. Abdominal examination x. Rectal examination (if want to obtain a stool sample for occult blood or culture) c. Laboratory Exam (usually not necessary in mild to moderate dehydration in children): i. Serum electrolytes (sodium and bicarbonate) ii. Urinanalysis (for specific gravity, ketones) iii. Stool studies including culture (mucous and/or leukocytes in the stool more likely bacterial infection) iv. Stool for ova and parasites (especially if Giardia lamblia or Cryptosporidium is suspected) Table 1. Clinical Criteria Commonly used for Classifying Dehydration Severity General Appearance/ Level of consciousness* Mild (3 5%) Moderate (6 9%) Severe (> 10%) Well appearing Ill appearing, non toxi Lethargic, toxic Heart Rate Normal to increased Tachycardic Marked tachycardia Breathing pattern* Normal Increased Increased, deep Pulses Normal quality Normal to thready Faint, impalpable Capillary refill* Normal (< 2sec) Normal to sl prolonged (2 4sec) Markedly prolonged Perfusion Warm Cool Cold, mottled Blood pressure Normal Normal Hypotensive Eyes Normal Slightly sunken Very sunken Tears Normal Decreased Absent Mucous membranes Moist Tacky Very Dry Skin turgor/recoil* Instant recoil Delayed (2 sec) Very prolonged (> 2sec) Urine output Normal to slightly decreased Decreased Adapted as a composite from WHO 1995, Gorelick 1997, Friedman 2004 Minimal 4 items with the highest predictive value for dehydration: general appearance, heart rate, capillary refill, and skin turgor/recoil Management: Use of oral rehydration therapy has significantly decreased the need for inpatient, intravenous hydration. Who should be hospitalized for IV fluids: children with greater than 10% dehydration or hypernatremic (sodium > 150) dehydration. Children who are 5% to 10% dehydrated tend to do well with ORT and this should be attempted initially. Contraindications to this include severe protracted vomiting or inability of the parents or guardians to follow the appropriate ORT guidelines for the child.

4 Children who are < 5% dehydrated, ORT should always be attempted first. Key Points of Oral Rehydration Therapy (ORT) Oral rehydration, using an appropriate oral rehydration solution (ORS) is the preferred method of choice Rehydration should be performed rapidly (over 2 4 hours) Successful ORT involves several phases: o Rehydration o Maintenance and prevention of dehydration o Realimentation Laboratory testing is usually not necessary Medications are usually not necessary Following rehydration, rapid realimentation involves using an age appropriate, unrestricted diet that should begin as soon as possible. o Both formula and breastfed infants should be started back on their usual feedings as soon as possible. o Partial dilution of formula, and restriction of lactose are not necessary. Essentials of Oral Rehydration Therapy 1. Select an appropriate fluid (Pedialyte if <2yo; Gatorade if >2yo). Do Not use plain water, juices, or soda. 2. Begin with a proscribed amount, at a proscribed interval (for example., 5 10 cc every 5 minutes) 3. A syringe is recommended for ease of administration. 4. Increase the volume and/or frequency of the fluid as tolerated 5. The initial goal is to give minimum 10cc/kg bolus over first hour 6. Overall goal is to replace the total estimated deficit for the patient in a maximum of 4 hours Most of the bacterial agents causing diarrheal illness (with the exception of C. Difficile), are likely to produce an acute and self limited course, not requiring antibiotics. To help protect against rotavirus, the vaccine is the best for prevention. Antidiarrheal agents in the pediatric population are not recommended. Table 2. Constituent components and Recommendations for Oral Rehydration Therapy (ORT) Osmolality (mosm/kg) Glucose (mmol/l) Sodium (mmol/l) Potassium (mmol/l) Recommendation as an ORS WHO Recommended for All Low Osmlarity WHO Commercial ORS (i.e., Pedialyte ) Sports Drink (i.e., Gatorade ) ages Recommended for All ages Recommended for All ages Not recommended Cola Not recommended

5 Seven up Not recommended Orange juice Not recommended Apple juice Not recommended Adapted from Sandhu 2001 pg S37 PREP Questions about acute gastroenteritis: 1. You are seeing a 1 month old girl for follow up after a hospitalization for acute gastroenteritis caused by rotavirus. Her diarrhea had decreased in the hospital while taking oral rehydration solution, but when her mother resumed her usual cow milk formula, the girl began to have an increased number of very watery stools. She appears well hydrated, and findings on her abdominal examination are normal. Of the following, the MOST appropriate approach to managing this infant's diarrhea is to: a. change to a lactose free formula for the next few days b. dilute the cow milk formula with oral rehydration solution for the next few days c. give her only oral rehydration solution until the diarrhea resolves d. readmit her to the hospital for administration of intravenous fluids e. repeat her stool studies to confirm the diagnosis of rotavirus infection 2. You are the physician for the child care center that your child attends. When an outbreak of diarrhea occurs at the center, the director calls you. She knows infections due to Giardia lamblia are common in child care centers, but asks if she needs to be worried about anything else. Of the following, the organism MOST likely to cause a child care outbreak is: a. Aeromonas hydrophila b. Campylobacter jejuni c. Salmonella sp d. Shigella sp e. Yersinia enterocolitica 3. You are called by the director of a preschool regarding an outbreak of gastroenteritis that occurred in the 2 and 3 year old toddler classes. She states that 8 of 20 children developed vomiting and diarrhea associated with fever several days after the school picnic. All the children recovered from their illness after about 1 week. Of the following, the MOST likely causative organism was: a. adenovirus b. Bacillus cereus c. Coxsackievirus d. Rotavirus e. Staphylococcus aureus 4. A 2 year old boy presents with a 3 day history of diarrhea and vomiting. He has been able to tolerate small amounts of fluids. He is moderately dehydrated, with dry mucous membranes and a heart rate of 145 beats/min. Of the following, the BEST management for this patient's fluid status is: a. hospitalization with intravenous fluids and a restrictive bland diet b. hospitalization with intravenous fluids and gut rest for 24 hours c. oral rehydration therapy at home followed by a clear liquid diet for 24 hours d. oral rehydration therapy at home followed by a diet of fruits, vegetables, and meats e. oral rehydration therapy at home followed by a restrictive bland diet 5. A 5 month old female infant presents with a 1 day history of fever to 102 F (38.9 C), emesis, and

6 multiple episodes of greenish diarrhea. Her mother states that the infant is less active, sleepier, and has no interest in feeding. Physical examination reveals a listless infant who has a sunken anterior fontanelle, dry mucous membranes with decreased skin turgor, and skin irritation in the diaper area. Of the following, the MOST likely cause of this patient's gastroenteritis is: a. astrovirus b. Escherichia coli c. Norwalk virus d. Rotavirus e. Salmonella sp Answers: 1. A. The infant described in the vignette most likely has lactase deficiency due to rotavirus infection. Lactase is an enzyme found in the most superficial villous portion of the intestinal brush border, which hydrolyzes lactose to glucose and galactose. Lactase deficiency may have several causes in children and adults. Primary lactase deficiency, the most common type, is a genetically determined condition that affects children and adults at different ages but is unusual before 5 years. Symptoms include abdominal distention, bloating, flatulence, or nausea after the ingestion of lactose, with the amount of lactose needed to cause such symptoms varying from person to person. The diagnosis is made by breath hydrogen testing, and management consists of removing some or all lactose from the diet. Congenital lactase deficiency is extremely rare. Secondary lactase deficiency may develop after an infectious gastroenteritis, such as rotavirus, giardiasis, or cryptosporidiosis. Other causes include celiac disease and enteropathy related to immunodeficiency. Secondary lactase deficiency is suggested when a child who has a recent diarrheal illness experiences worsening diarrhea or bloating after the reintroduction of lactose into the diet, as described for the girl in the vignette. Most children who have gastroenteritis do not develop lactase deficiency. For this reason, most infants can tolerate and should continue taking human milk or standard lactose containing formula throughout a diarrheal illness. For very young infants (eg, <3 months old), such as the one described in the vignette, or those who have significant fluid losses, a lactose free formula may be attempted until the diarrhea resolves. Infants who are breastfed should be encouraged to continue breastfeeding, even if secondary lactase deficiency is suspected. Giving full strength formula or human milk is recommended to supply the child with sufficient calories during the recovery phase of a diarrheal illness; therefore, diluting the formula or providing only oral rehydration solution is inappropriate. If the child is not vomiting, oral hydration is optimal, and intravenous hydration is not necessary. There is no need to confirm the diagnosis of rotavirus infection; doing so would not alter management plans. 2. D. Outbreaks of diarrheal illness can occur in child care facilities when caretakers do not adhere to hand hygiene policies and the pathogen requires a small inoculum for disease production. Giardia lamblia and Shigella sp commonly cause child care center outbreaks. Shigella are gram negative bacilli that are spread readily person to person through fecal oral and oral anal contamination or by houseflies or other contaminated fomites. Among the common bacterial causes of gastroenteritis, Shigella is unique because ingestion of as few as 10 organisms can cause human disease. There are four primary Shigella pathogens: S sonnei, S flexneri, S boydii, and S dysenteriae.

7 The typical incubation period is 2 to 4 days, and the illness caused by Shigella can range from a mild diarrhea to life threatening dysentery. Fever and abdominal cramps with high volume, watery stools followed 24 to 48 hours later by small volume, bloody mucoid stools with tenesmus is a common presentation. Bloody mucoid stools are more common with diarrhea due to S dysenteriae and S flexneri; S boydii and S sonnei usually cause only watery diarrhea. Seizures can occur, with an incidence that is higher than would be expected from febrile seizures alone. Other complications can include Reiter syndrome, hemolytic uremic syndrome, colonic perforation, and toxic encephalopathy. Stool microscopy revealing a large number of neutrophils in a patient who has clinical findings suggestive of shigellosis supports the diagnosis but is not specific for any species of Shigella. Aeromonas hydrophila, Campylobacter jejuni, Salmonella sp, and Yersinia enterocolitica are not commonly involved in outbreaks of gastrointestinal disease in child care centers due to their large inoculum requirements. 3. A. Diarrheal diseases in children younger than 5 years of age remain one of the leading causes of morbidity and mortality in developing countries and are an important cause of morbidity in developed countries. In the United States, children in this age range have 35 to 40 million episodes of diarrhea annually, resulting in about 170,000 hospitalizations and 300 deaths due to complications from diarrheal disease. (Item C187A) lists the most common viral and bacterial diarrheal pathogens in children by age group. Most of the infectious organisms that cause diarrhea are spread via the fecal oral route or through contaminated food and water. Enteric adenovirus disease primarily affects children younger than 4 years of age, although infection may occur at any age. Noroviruses (formerly Norwalk virus or Norwalk like virus) may be associated with the consumption of raw seafood, ice, salads, and cookies, usually contaminated by infected food handlers. Noroviruses are common causes of sporadic illness in children younger than 4 years of age, but outbreaks of gastroenteritis may occur in all age groups. Outbreaks tend to occur in closed populations, such as child care centers and cruise ships, and there is a high attack rate. Water also has been documented as a vehicle of transmission of Giardia lamblia, Campylobacter, Cryptosporidium, and noroviruses. Child care centers serve as important reservoirs for transmission of diarrheal agents, with the peak incidence of diarrhea occurring in children younger than 3 years of age who are not toilet trained. The children described in the vignette most likely developed diarrhea after ingesting contaminated food or water at the school picnic. Given the timing of the development of the diarrhea, the children most likely have adenoviral gastroenteritis. Most children have been infected with rotavirus by the age of 3 years, and rotavirus gastroenteritis typically is not associated with spread from contaminated food and water. Coxsackievirus infection commonly manifests as gastrointestinal symptoms when there is systemic disease, but such symptoms rarely are the major complaint. The children in the vignette demonstrate no other findings consistent with systemic Coxsackievirus infection. Staphylococcus aureus and Bacillus cereus both are causes of gastroenteritis, but the illness associated with both organisms usually develops within 1 to 8 hours after ingestion of the contaminated food item. Further, both illnesses are self limited and usually resolve within 48 hours of onset. 4. D. Dehydration results from a total body loss of water and sodium. Acute infectious gastroenteritis is among the most common causes of dehydration in infants and young children. Both mild and moderate dehydration may be managed at home with oral rehydration therapy, even if the child continues to have intermittent vomiting. Commercial oral rehydration solutions (ORS) are widely available and should be

8 used for this purpose. All ORS are designed to replace lost electrolytes (sodium, chloride, potassium, and bicarbonate) glucose, and water. Young children who have mild dehydration have an estimated water loss of 50 ml/kg, and this amount of ORS can be given via a spoon or syringe in small amounts over 2 to 4 hours. Those who have moderate dehydration should receive 100 ml/kg over 2 to 4 hours. Care should be taken to monitor ongoing losses from stool and emesis, and intravenous or nasogastric rehydration therapy should be considered if losses are excessive or if dehydration worsens or does not improve. Oral rehydration therapy should not be used for children who have severe dehydration, shock, suspected intestinal obstruction, obtundation, or ileus. Once adequate hydration has been assured or rehydration is complete, a normal diet should be given to the child to ensure adequate caloric and nutrient intake. A period without gastrointestinal intake is unnecessary and may delay nutritional recovery. Clear liquid and bland diets also should not be used because they do not provide adequate nutrition. Infants should be given human milk or their usual formula at full strength because diluted formula or human milk (eg, one half or one quarter strength formula) will not meet the child's caloric requirements and may worsen electrolyte abnormalities. Lactose free formulas are generally unnecessary because most children do not develop lactase deficiency. Older children should be given a regular diet of complex carbohydrates, fruits, vegetables, and meats. High sugar containing liquids should be avoided because the osmotic load of these liquids may worsen diarrhea. 5. D. Diarrheal diseases in children younger than 5 years of age remain one of the leading causes of morbidity and mortality in developing countries and are important causes of morbidity in developed countries. In the United States, children 5 years of age and younger have between 35 and 40 million episodes of diarrhea annually, resulting in about 170,000 hospitalizations and 300 deaths due to complications. (Item C206A) shows the most common viral and bacterial diarrheal pathogens in children by age group. Most of the infectious organisms that cause diarrhea are spread via the fecal oral route. Organisms such as Shigella, Giardia, and Campylobacter also may be transmitted by person to person contact because of their low infective inoculum dose. Foodborne diseases affect all age groups. Common causes include: E coli 0157:H7 (EHEC) associated with ingestion of undercooked meat, Salmonella and Campylobacter associated with contaminated poultry products and unpasteurized milk, Yersinia enterocolitica associated with contaminated pork products, and Norwalk virus associated with the consumption of raw seafood. Water also has been documented as a vehicle of transmission for Giardia lamblia, Campylobacter, Cryptosporidium, and Norwalk virus. Child care centers serve as important reservoirs for transmission of infectious diarrheal agents, with the peak incidence of diarrhea occurring in children younger than 3 years of age who are not toilet trained. Rotavirus (seen most commonly in children younger than 12 months of age), Shigella, and Giardia have been associated with outbreaks in child care centers. The child described in the vignette has diarrhea caused by rotavirus, the most common cause of viral diarrheal disease in infants and toddlers. Norwalk virus and E coli are not common causes of diarrhea in young infants. Astrovirus is a cause of diarrhea in children younger than 4 years of age, but most of the infections are asymptomatic. Salmonella sp also may cause diarrhea in infants, but it is much less common than a viral etiology, especially in developed countries.

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