AUTHOR INFORMATION

Section 1 of 11

Authored by Adam Levine, MD, MPH, Staff Physician, Department of Emergency Medicine, Brigham and Women's Hospital & Massachusetts General Hospital

Coauthored by Karen A Santucci, MD, Fellowship Director of Pediatric Emergency Medicine, Assistant Professor, Department of Pediatrics, New Haven Children's Hospital, Yale University; David W Marby, MD †, Former Consulting Staff, Department of Pediatric Emergency Medicine, Brown University School of Medicine, Hasbro Children's Hospital

Adam Levine, MD, MPH, is a member of the following medical societies: American College of Emergency Physicians, American Medical Association, American Public Health Association, Emergency Medicine Residents' Association, and Massachusetts Medical Society

Edited by James Li, MD, Assistant Professor, Division of Emergency Medicine, Harvard Medical School; Consulting Staff, Department of Emergency Medicine, Miles Memorial Hospital; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Wayne Wolfram, MD, MPH, Clinical Associate Professor, Departments of Pediatrics, Children's Hospital and University of Cincinnati; John Halamka, MD, Chief Information Officer, CareGroup Healthcare System, Assistant Professor of Medicine, Department of Emergency Medicine, Beth Israel Deaconess Medical Center; Assistant Professor of Medicine, Harvard Medical School; and Richard G Bachur, MD, Assistant Professor of Pediatrics, Harvard Medical School; Associate Chief and Fellowship Director, Division of Emergency Medicine, Children's Hospital of Boston

Author's Email:	Adam Levine, MD, MPH
Editor's Email:	James Li, MD

eMedicine Journal, June 14 2006, VOLUME 7, Number 6

INTRODUCTION

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Background: Though often considered a benign disease, acute gastroenteritis remains a major cause of morbidity and mortality in children around the world, accounting for 1.8 million deaths annually in children younger than 5 years, or roughly 17% of all child deaths. Because the severity of the disease can vary widely depending on the volume of fluid loss, accurately assessing and treating dehydration in children presenting with acute gastroenteritis remains a critical skill for every emergency physician. Luckily, most cases of dehydration in children can be accurately diagnosed by a careful clinical examination and treated with simple, cost-effective measures.

Pathophysiology: Adequate fluid balance in humans depends on the secretion and reabsorption of fluid and electrolytes in the intestinal tract; diarrhea occurs when intestinal fluid output overwhelms the absorptive capacity of the gastrointestinal tract. The two primary mechanisms responsible for acute gastroenteritis are (1) damage to the villous brush border of the intestine, causing malabsorption of intestinal contents and leading to an osmotic diarrhea, and (2) the release of toxins that bind to specific enterocyte receptors and cause the release of chloride ions into the intestinal lumen, leading to secretory diarrhea.

Even in severe diarrhea, various Na-coupled solute cotransport mechanisms remain intact, allowing for the efficient reabsorption of salt and water. By providing a 1:1 proportion of Na to glucose, classic oral rehydration solution (ORS) takes advantage of a specific Na-glucose transporter (SGLT-1) to increase the reabsorption of Na, which leads to the passive reabsorption of water. Alternatively, rice- and cereal-based ORS take advantage of Na-amino acid transporters to increase reabsorption of fluid and electrolytes.

Frequency:

• In the US: In the United States, acute gastroenteritis remains a major cause of morbidity in children, accounting for than 1.5 million outpatient visits, 200,000 hospitalizations, and 300 deaths each year.

• Internationally: Worldwide, children younger than 5 years suffer from an estimated 1.4 billion episodes of diarrhea each year, leading to 123 million clinic visits, 9 million hospitalizations, and 1.8 million deaths. Although the absolute number of cases of acute gastroenteritis has changed little over the past 4 decades, the mortality has declined sharply, from 4.6 million in the 1970s to 3 million in the 1980s to 2.5 million in the 1990s.

  One of the most important reasons for this decline has been the increasing international support for the use of ORS as the treatment of choice for acute diarrhea, with the proportion of diarrheal episodes treated with ORS rising from 15% in 1984 to 40% in 1993.

CLINICAL

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History: The history helps both in differentiating gastroenteritis from other, often more serious, causes of vomiting and diarrhea in children, and in estimating the degree of dehydration. In some cases, the history can also aid in determining the type of pathogen responsible for the gastroenteritis, though only rarely will this effect management.

• Diarrhea: Duration of diarrhea, the frequency and amount of stools, the time since last episode of diarrhea, and the quality of stools. Frequent, watery stools are more consistent with viral gastroenteritis, while stools with blood or mucous are indicative of a bacterial pathogen. Similarly, a long duration of diarrhea (>14 d) is more consistent with a parasitic or noninfectious cause of diarrhea.

• Vomiting: Duration of vomiting, the amount and quality of vomitus (ie, food contents, blood, bile), and time since the last episode of vomiting. When symptoms of vomiting predominate, one should consider other diseases such as gastroesophageal reflux disease (GERD), gastric outlet (eg, pyloric stenosis) or intestinal obstruction (eg, hernia, intussusception), CNS etiologies, diabetic ketoacidosis, or urinary tract infection. Bilious emesis may represent intestinal obstruction.

• Urine output: Increase or decrease in frequency of urination measured by number of wet diapers, time since last urination, color and concentration of urine, and presence of dysuria. Urine output may be difficult to determine with frequent watery stools.

• Abdominal pain: Location, quality, radiation, severity, and timing of pain, per report of parents and/or child. In general, pain that precedes vomiting and diarrhea is more likely to be due to abdominal pathology other than gastroenteritis.

• Signs of infection: Presence of fever, chills, myalgias, rash, rhinorrhea, sore throat, cough. These symptoms may indicate evidence of systemic infection or sepsis.

• Appearance and behavior: Weight loss, quality of feeding, amount and frequency of feeding, level of thirst, level of alertness, increased malaise, lethargy, or irritability, quality of crying, and presence or absence of tears with crying.

• Antibiotics: History of recent antibiotic use increases the likelihood of Clostridium difficile colitis.

• Travel: History of travel to endemic areas may make prompt consideration of relatively rare organisms, such as parasitic diseases or cholera.

Physical: The physical examination should confirm and clarify the assessment of dehydration and should narrow diagnostic possibilities generated by the history.

• General: Weight, appearance, level of alertness, lethargy, irritability

• HEENT: Presence or absence of tears, dry or moist mucous membranes, sunken eyes, or sunken fontanelle

• Cardiovascular: Heart rate, blood pressure, quality of pulses, perfusion, temperature of skin and distal extremities

• Respiratory: Rate and quality of respirations; the presence of deep, acidotic breathing increases the likelihood of dehydration.

• Abdomen: Abdominal tenderness, guarding, and rebound, bowel sounds. Abdominal tenderness on examination, with or without guarding, should prompt consideration of diseases other than viral gastroenteritis.

• Back: Flank/costovertebral angle (CVA) tenderness increases the likelihood of pyelonephritis.

• Rectal: Quality and color of stool, presence of gross blood or mucous

• Extremities: Capillary refill time, warm or cool extremities

• Skin: Abdominal rash may indicate typhoid fever (infection with Salmonella typhi) while jaundice might make viral or toxic hepatitis more likely.

Causes: Identifying the specific etiologic agent responsible for the acute gastroenteritis rarely changes management. However, it may be helpful to differentiate between viral, bacterial, parasitic, and noninfectious causes of diarrhea.

• By far, viruses remain the most common cause of acute gastroenteritis in children, in both the developed world and the developing world. Viral gastroenteritis typically presents with low-grade fever and vomiting followed by copious watery diarrhea (up to 10-20 bowel movements per day), with symptoms persisting for 3-8 days.

• Rotavirus represents the most important viral pathogen, responsible for up to half of all cases of acute gastroenteritis in developed countries, and 5-20% of cases diarrhea in developing countries.

• Enteric adenoviruses may be the second most common cause of viral gastroenteritis in developed countries, accounting for 5-20% of pediatric gastroenteritis.

• Noroviruses (Norwalk-like viruses) are responsible for 68-80% of all outbreaks of gastroenteritis, such as food-borne outbreaks, in developed countries.

• In developed countries, bacterial pathogens account for a small portion, perhaps 2-10%, of all cases of pediatric gastroenteritis. Relative to viral gastroenteritis, bacterial disease is more likely to be associated with high fevers, shaking chills, bloody bowel movements (dysentery), abdominal cramping, and fecal leukocytes.

• In the United States, the most important pathogens, in order of prevalence, are Campylobacter, Salmonella, and Shigella, species and enterohemorrhagic Escherichia coli (EHEC).

• In developing countries, enterotoxigenic E coli (ETEC) remains the most important bacterial cause of acute gastroenteritis in children, while also causing most cases of traveler’s diarrhea in all age groups. Unlike other bacterial causes of gastroenteritis, ETEC is unlikely to cause dysentery.

• C difficile has emerged as an important cause of antibiotic associated diarrhea in children. Since 50% of neonates and young infants are colonized with C difficile, symptomatic disease is unlikely in children younger than 12 months.

• Cholera, caused by the organism Vibrio cholerae, leads to severe watery diarrhea and rapid dehydration. It generally occurs in the setting of epidemics due to poor water quality and sanitation.

• Parasites remain yet another source of gastroenteritis in young children, with Giardia and Cryptosporidium species the most common causes in the United States. Parasitic gastroenteritis generally present with watery stools, but it can be differentiated from viral gastroenteritis by a protracted course or history of travel to endemic areas.

DIFFERENTIALS

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Diabetic Ketoacidosis
Gastritis and Peptic Ulcer Disease
Giardiasis
Hemolytic Uremic Syndrome
Hepatitis
Inflammatory Bowel Disease
Pancreatitis
Pediatrics, Appendicitis
Pediatrics, Foreign Body Ingestion
Pediatrics, Intussusception
Pediatrics, Pyloric Stenosis
Pediatrics, Urinary Tract Infections and Pyelonephritis
Shock, Septic

Other Problems to be Considered:

Pseudomembranous colitis
Malrotation
Volvulus
Food poisoning
Lactose intolerance
Malabsorption syndromes
Irritable bowel syndrome

WORKUP

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Lab Studies:

• The vast majority of children presenting with acute gastroenteritis do not require lab tests, as they are unlikely to affect management.

• In a recent meta-analysis of 6 studies, BUN, Cr, pH, anion gap, and urine specific gravity were not found to be useful measures of dehydration.

• Only serum bicarbonate ( <17) had statistically significant likelihood ratios for detecting moderate dehydration.

• Clinically significant electrolyte abnormalities are rare in children with moderate dehydration.

• Any child being treated with intravenous fluids for severe dehydration should have baseline electrolytes, bicarbonate, and urea/creatinine drawn.

• Electrolytes are also indicated in patients with moderate dehydration whose history and physical are inconsistent with straightforward gastroenteritis or whose skin has a "doughy" feel, which might indicate hypernatremia.

• Fecal leukocytes and stool culture may be helpful in children presenting with dysentery.

• Children older than 12 months with a recent history of antibiotic use should have stool tested for C difficile toxins.

• Children with a history of prolonged watery diarrhea (>14 d) or travel to an endemic area should have stool sent for ova and parasites.

• Any child with evidence of systemic infection should have a complete workup including CBC and blood cultures. If indicated, urine cultures, chest radiography, and/or lumbar puncture (LP) should be performed.

Imaging Studies:

• Abdominal films are not indicated in the management of acute gastroenteritis. If the clinician suspects a diagnosis other than acute gastroenteritis based on history and physical examination, appropriate imaging modalities should be pursued.

Other Tests:

• Workup of acute gastroenteritis should include a formal assessment of the level of dehydration in the child based on elements of the history and physical examination.

• Both the American Academy of Pediatrics (AAP) and the Centers for Disease Control and Prevention (CDC) recommend using a dehydration scale to classify the total body water loss occurring with gastroenteritis as mild (3-5%), moderate (6-9%), or severe (>10%) (see Table 1).

  Table 1. Assessment of Dehydration*
  

  Variable	Mild (3-5%)	Moderate (6-9%)	Severe (ˇÝ10%)
  Blood pressure	Normal	Normal	Normal to reduced
  Quality of pulses	Normal	Slightly diminished	Moderately diminished
  Heart rate	Normal	Increased	Increased
  Skin turgor	Normal	Decreased	Decreased
  Fontanelle	Normal	Sunken	Sunken
  Mucous membranes	Slightly dry	Dry	Dry
  Eyes	Normal	Sunken orbits	Deeply sunken orbits
  Extremities	Normal cap refill	Delayed cap refill	Cool, mottled
  Mental status	Normal	Listless	Lethargic, comatose
  Urine output	Slightly decreased	<1 mL/kg/h	< <1 mL/kg/h
  Thirst	Slightly decreased	Moderately increased	Too lethargic to indicate

  
  *Adapted from Practice parameter: The management of acute gastroenteritis in young children. American Academy of Pediatrics, Provisional Committee on Quality Improvement, Subcommittee on Acute Gastroenteritis. Pediatrics. 1996 Mar; 97(3):424-35.

• The World Health Organization (WHO) recommends a simpler system for use by both physicians and lay health workers, which classifies dehydration as none, some, or severe (see Table 2).

  Table 2: Assessment of Dehydration*
  

  Severe dehydration	Two of the following signs: • Lethargic or unconscious • Sunken eyes • Not able to drink or drinking poorly • Skin pinch goes back very slowly
  Some dehydration	Two of the following signs: • Restless, irritable • Sunken eyes • Thirsty, drinks eagerly • Skin pinch goes back slowly
  No dehydration	Not enough of the above signs to classify as some or severe dehydration

  
  * Adapted from World Health Organization. The treatment of diarrhoea: a manual for physicians and other senior health workers. 4th rev. 2005.

• A recent meta-analysis of 13 separate studies looking at individual signs and symptoms of dehydration found only abnormal cap refill (>2 sec), decreased skin turgor, and abnormal respiratory pattern (hyperpnea) had statistically significant positive and negative likelihood ratios for detecting dehydration in children.

• A study by Gorelick et al assessed the validity of a combination of 10 signs and symptoms similar to those recommended by the American Academy of Pediatrics (AAP). They found that the presence of 3 or more signs had a sensitivity of .87 and a specificity of .82 for detecting moderate dehydration. The presence of 7 or more signs had a sensitivity of .82 and a specificity of .90 for detecting severe dehydration.

TREATMENT

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Emergency Department Care: The American Academy of Pediatrics, the European Society of Pediatric Gastroenterology and Nutrition (ESPGAN), and the World Health Organization all recommend ORS as the treatment of choice for children with mild-to-moderate gastroenteritis in both developed and developing countries, based on the results of dozens of randomized, controlled trials and several large meta-analyses. One large meta-analysis of 16 trials including 1545 children with mild-to-moderate dehydration found that, compared with intravenous rehydration, children treated with ORS had a significant reduction in length of hospital stay and fewer adverse events, including seizures and death. In most large trials, the rate of ORS failure (percentage of children eventually requiring intravenous hydration) was about 4%.

• Minimal or no dehydration: No immediate treatment is required. Instruction to caretakers about ORS and instruction regarding signs of dehydration are recommended.

• Mild-to-moderate dehydration: Children should be given 50-100 mL/kg of ORS over a 2- to 4-hour period to replace their estimated fluid deficit, with additional ORS given to replace ongoing losses (10 mL/kg body weight for each stool and 2 mL/kg body weight for each episode of emesis). After the initial rehydration phase, patients may be transitioned to maintenance fluids as described above.

• ORS should be given slowly by the parent using a teaspoon, syringe, or medicine dropper at the rate of 5 mL every 1-2 minutes. If tolerated by the patient, the rate of ORS delivery can be increased slowly over time.

• For patients who do not tolerate ORS by mouth due to persistent vomiting or oral ulcers, nasogastric (NG) feeding is a safe and effective alternative. Multiple large clinical trials have found NG rehydration to be as efficacious as intravenous rehydration but more cost-effective and with fewer adverse events.

• Patients with moderate dehydration should be reassessed frequently by the clinician to ensure adequacy of oral intake and resolution of the various signs and symptoms of dehydration.

• Severe dehydration: This constitutes a medical emergency requiring immediate resuscitation with intravenous fluids.
  • Intravenous access should be obtained, and patients should be administered repeat boluses of 20 mL/kg lactated Ringer (LR) or normal saline (NS) until pulse, perfusion, and mental status return to normal. If no peripheral veins are available, an intraosseous line should be placed. Serum electrolytes, bicarbonate, urea/creatinine, and glucose levels should be sent.

  • Once resuscitation is complete and mental status returns to normal, rehydration should continue with ORS as described above, as it has been shown to decrease the rate of hyponatremia and hypernatremia when compared to intravenous rehydration.

• Type of ORS: Two large meta-analyses confirm that reduced osmolarity ORS (osmolarity < 250 mmol/L) is associated with fewer treatment failures requiring intravenous hydration, lower stool output, and less frequent vomiting compared with standard osmolarity ORS for patients with noncholera gastroenteritis.

• Multiple preparations of reduced osmolarity ORS are available in the United States, including Pedialyte, Infalyte, and Naturalyte. Available formulations in Europe include Dioralyte and Diocalm Junior. In developing countries, clinicians can use WHO ORS or a homemade solution of 3 g (1 tsp) salt and 18 g (6 tsp) sugar added to 1 L of clean water.

• A recent large meta-analysis found that patients with cholera had higher rates of hyponatremia with reduced osmolarity ORS compared with standard osmolarity ORS, without any of the added benefits seen in patients with noncholera gastroenteritis.

• Feeding and nutrition: In general, children with gastroenteritis should be returned to a normal diet as rapidly as possible. Early feeding reduces illness duration and improves nutritional outcome.

• Breastfed infants should continue to breastfeed throughout the rehydration and maintenance phases of acute gastroenteritis.

• Formula fed infants should restart feeding at full strength as soon as the rehydration phase is complete (ideally in 2-4 h).

• Weaned children should restart their normal fluids and solids as soon as the rehydration phase is complete. Fatty foods and foods high in simple sugars should be avoided.

• For most infants, clinical trials have found no benefit of lactose-free formulas over lactose-containing formulas. Similarly, highly specific diets, such as the BRAT (bananas, rice, applesauce, and toast) diet, have not been shown to improve outcomes and may provide suboptimal nutrition for the patient.

MEDICATION

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The goals of pharmacotherapy are to reduce morbidity, prevent complications, and prophylaxis. Antidiarrheal (ie, kaolin-pectin) and antimotility agents (ie, loperamide) are contraindicated in the treatment of acute gastroenteritis in children because of their lack of benefit and increased risk of side effects, including ileus, drowsiness, and nausea.

Probiotics are live microbial feeding supplements commonly used in the treatment and prevention of acute diarrhea. Possible mechanisms of action include synthesis of antimicrobial substances, competition with pathogens for nutrients, modification of toxins, and stimulation of nonspecific immune responses to pathogens. Several large studies and two recent meta-analyses have found probiotics (especially Lactobacillus GG) to be effective in reducing the duration of diarrhea in children presenting with acute gastroenteritis.

Several large studies, all conducted in developing countries, have shown zinc supplementation to be effective in reducing the duration and severity of diarrhea in children with acute gastroenteritis, as well as the likelihood of recurrence of diarrhea. The WHO recommends zinc supplementation (10-20 mg/d for 10-14 d) for all children younger than 5 years with acute gastroenteritis, although little data exist to support this recommendation for children in developed countries.

Drug Category: Vaccines -- In February 2006, the FDA approved the RotaTeq vaccine for prevention of rotavirus gastroenteritis. The vaccine has been endorsed by the AAP and is currently the only available vaccine for the prevention of viral gastroenteritis in infants and children.

Drug Name	Rotavirus vaccine (RotaTeq) -- Orally administered live-virus vaccine. Pentavalent vaccine that contains 5 live reassortant rotaviruses. Indicated to prevent rotavirus gastroenteritis, a major cause of severe diarrhea in infants. Administered as a 3-dose regimen against G1, G2, G3, and G4 serotypes, the 4 most common rotavirus group A serotypes. Also contains attachment protein P1A (genotype P[8]). Clinical trials demonstrated prevention of 74% of all rotavirus gastroenteritis cases, nearly all severe rotavirus gastroenteritis cases, and nearly all hospitalizations due to rotavirus.
Adult Dose	Not indicated
Pediatric Dose	<6 weeks: Not established 6-12 weeks: 2 mL PO as a single dose, followed by 2 additional doses at 4- to 10-wk intervals; do not administer after age 32 wk >32 weeks: Not established
Contraindications	Documented hypersensitivity
Interactions	Immunosuppressive therapies (eg, irradiation, antimetabolites, alkylating agents, cytotoxic drugs, high-dose corticosteroids) may decrease immune response
Pregnancy	C - Safety for use during pregnancy has not been established.
Precautions	Common adverse effects include diarrhea, vomiting, otitis media, inflamed nasal passages, and bronchospasm; refrigerate and protect from light; handle and discard empty tube according to biological waste procedures; previously marketed rotavirus vaccine (RotaShield) was associated with intussusception, but RotaTeq did not show an increased risk compared with placebo in clinical trials (monitor for signs of intestinal blockage); do not mix with other vaccines or solutions

Drug Category: Antimicrobials -- Since the majority of cases of acute gastroenteritis in developed and developing countries are due to viruses, antibiotics are generally not indicated. Even in cases (eg, dysentery) where a bacterial pathogen is suspected, antibiotics may be ineffective (Campylobacter), may prolong the carrier state (Salmonella), or may increase the risk of hemolytic uremic syndrome (enterohemorrhagic E coli).

In patients with positive stool assays or high clinical suspicion for C difficile, the offending antibiotic should be stopped immediately. Metronidazole (30 mg/kg/d divided qid for 7 d) can be used as a first-line agent, with oral vancomycin reserved for resistant infections.

Although generally not recommended for children younger than 8 years, tetracycline (50 mg/kg/d divided qid for 3 d) and doxycycline (6 mg/kg single dose) remain the treatment of choice for cholera. Alternative treatments with good efficacy include erythromycin and ciprofloxacin.

For patients with ova and parasites (O+P) confirming infection with Giardia, metronidazole (35-50 mg/kg/d divided q8h) remains the drug of choice. Nitazoxanide oral suspension (age 1-3: 100 mg q12h for 3 d, age 4-11: 200 mg q12h for 3 d) is as effective as metronidazole and has the added benefit of treating other intestinal parasites, such as Cryptosporidium.

Drug Name	Metronidazole (Flagyl) -- Recommended as the treatment of choice for mild-to-moderate cases of C difficile colitis. Provides effective therapy, with reported response rates from 95-100%. In vitro activity is bactericidal and dose dependent. Standard dosing has been shown to promote fecal concentrations capable of a 99.99% reduction of C difficile. Metronidazole IV may be administered to those patients who cannot tolerate PO medications because of its potential to accumulate in the inflamed colon. IV route is not as effective as PO.
Pediatric Dose	30 mg/kg/d PO divided qid for 7 d
Contraindications	Documented hypersensitivity
Interactions	May increase toxicity of anticoagulants, cyclosporine, lithium, phenytoin, tacrolimus, and carbamazepine; cimetidine may increase toxicity of metronidazole; disulfiram reaction may occur with orally ingested ethanol; coadministration increases amiodarone toxicity (QT prolongation); increases disulfiram toxicity (psychotic symptoms) with concurrent use; phenobarbital and rifampin may increase metabolism of metronidazole
Pregnancy	B - Usually safe but benefits must outweigh the risks.
Precautions	Caution with liver impairment, blood dyscrasias, CNS disease; reduce dosage with severe hepatic disease; monitor for seizures and development of peripheral neuropathy

Drug Name	Nitazoxanide (Alinia) -- Inhibits growth of C parvum sporozoites and oocysts and G lamblia trophozoites. Elicits antiprotozoal activity by interference with the pyruvate: ferredoxin oxidoreductase (PFOR) enzyme-dependent electron transfer reaction, which is essential to anaerobic energy metabolism. Available as an oral suspension (20 mg/mL).
Pediatric Dose	<1 year: Not established 1-3 years: 100 mg (5 mL) PO q12h for 3 d with food 4-12 years: 200 mg (10 mL) PO q12h for 3 d with food >12 years: Administer as in adults
Contraindications	Documented hypersensitivity
Interactions	Tizoxanide (nitazoxanide metabolite) is >99.9% bound to plasma protein and may potentially increase toxicity of other highly plasma protein-bound drugs
Pregnancy	B - Usually safe but benefits must outweigh the risks.
Precautions	May cause abdominal pain, diarrhea, vomiting, or headache; administer with food; caution when coadministered with other highly plasma protein-bound drugs with narrow therapeutic indices.

Drug Category: Antiemetics -- A recent large, prospective, randomized, double-blind trial compared a single dose of an orally disintegrating ondansetron tablet to placebo in children presenting to an emergency department with acute gastroenteritis. The study found that children treated with ondansetron were less likely to vomit, had greater oral intake, were less likely to require intravenous rehydration, and had a reduced length of stay in the emergency department compared with children treated with placebo. Previous smaller studies have shown ondansetron to be similarly effective in children, although little data exist regarding the efficacy of other antiemetic drugs.

Drug Name	Ondansetron (Zofran) -- Selective 5-HT3-receptor antagonist that blocks serotonin both peripherally and centrally.
Pediatric Dose	<8 kg: Not established 8-15 kg: 2 mg PO once 15-30 kg: 4 mg PO once >30 kg: 8 mg PO once
Contraindications	Documented hypersensitivity
Interactions	Although potential for cytochrome P-450 inducers (barbiturates, rifampin, carbamazepine, and phenytoin) to change half-life and clearance of ondansetron, dosage adjustment is not usually required
Pregnancy	B - Usually safe but benefits must outweigh the risks.
Precautions	May cause headache

FOLLOW-UP

Section 8 of 11

Further Inpatient Care:

• Inpatient management includes frequent evaluation of volume status, replacement of fluid deficit and ongoing losses, and attempts at establishing and demonstrating oral intake sufficient to maintain volume status. Inpatient admission should be considered for all children with acute gastroenteritis in the following situations:

• Signs of severe dehydration are present.

• Caregivers are unable to manage oral rehydration or provide adequate care at home.

• Substantial difficulties exist in administering ORS, such as intractable vomiting or inadequate ORS intake.

• Failure of treatment occurs such as worsening diarrhea or dehydration despite adequate ORS intake.

• Factors are present necessitating closer observation, such as young age, decreased mental status, or uncertainty of diagnosis.

• Children with mild-moderate dehydration, age younger than 6 months, or high frequency of stools/vomits should be monitored in the emergency department for a minimum of 4-6 hours before discharge.

Further Outpatient Care:

• Parents should be instructed to continue providing maintenance ORS fluids at home as needed. Breastfeeding and formula feeding should be continued for infants, and children should be encouraged to return to a regular diet as rapidly as possible.

• Parents should be instructed to look for the various signs of dehydration outlined above, such as change in mental status, decreased urine output, sunken eyes/fontanelle, absence of tears, and dry mucous membranes.

• Parents should seek medical attention if dehydration returns, oral intake is inadequate, or if their child develops worsening abdominal pain, temperature higher than 101°F, or prolonged diarrhea lasting longer than 14 days.

Patient Education:

• For excellent patient education resources, visit eMedicine's Esophagus, Stomach, and Intestine Center. Also, see eMedicine's patient education article, Gastroenteritis.

MISCELLANEOUS

Section 9 of 11

Medical/Legal Pitfalls:

• Failure to diagnose appendicitis, intussusception, or small bowel obstruction places patients at risk of serious complications (including death).

• Clinical presentations that include these diagnoses as considerations should be thoroughly investigated and the clinician's evaluation clearly documented.

• Antidiarrheal medications have adverse effects and generally are not necessary.

TEST QUESTIONS

Section 10 of 11

CME Question 1: In assessing the degree of volume depletion from gastroenteritis using the physical examination findings and vital signs, what is the most sensitive evidence of volume depletion?

A: Fall in blood pressure
B: Increase in heart rate
C: Decrease in respiratory rate
D: Elevated temperature
E: None of the above

The correct answer is B: Blood pressure remains normal in children unless volume depletion is severe. The respiratory rate may increase in acidosis secondary to hypovolemia or during fever spikes. Temperature elevations are largely independent of volume status.

CME Question 2: A 5-year-old boy who recently completed a course of antibiotics for otitis media presents with a 3-day history of bloody diarrhea. One should especially consider which of the following?

A: Rotavirus
B: Astrovirus
C: Shigella
D: Salmonella
E: Clostridium difficile

The correct answer is E: Short courses of oral antibiotics can be associated with C difficile enteritis.

Pearl Question 1 (T/F): Rotavirus is the most common cause of diarrheal illness in children aged 3 months to 2 years.

The correct answer is True: Rotavirus is the identified etiologic agent in 12-71% of hospitalized children younger than 2 years with diarrheal illness.

Pearl Question 2 (T/F): Antidiarrheal compounds are not recommended in the treatment of acute gastroenteritis in children.

The correct answer is True: Clinical studies have not proven their effectiveness in children, and the complications related to specific agents are either too common or too risky (eg, ileus, respiratory depression).

Pearl Question 3 (T/F): Tap water is a good choice for oral rehydration.

The correct answer is False: Tap water does not contain electrolytes and may result in hyponatremia.

Pearl Question 4 (T/F): Parents should be advised to bring their child back to the emergency department if their child continues to vomit and have diarrhea.

The correct answer is False: Parent education should focus on helping them assess volume depletion and providing them with methods of succeeding at oral rehydration in the face of continued losses from vomiting and diarrhea. Vomiting and diarrhea may continue for several days and do not constitute an indication for a return visit. Parents should be advised to call their primary care provider or return to the emergency department for volume depletion that cannot be managed at home.

BIBLIOGRAPHY

Section 11 of 11

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