Chapter 73. Vomiting and Diarrhea in Infants and Children

Gastroenteritis is a major public health problem, accounting for up to 20% of all acute care outpatient visits to hospitals. Most children who come to the emergency department because of vomiting and/or diarrhea have a self-limited viral disorder. Nevertheless, loss of water and electrolytes can lead to clinical dehydration and may result in hypovolemic shock or life-threatening electrolyte disturbances.

The evaluation of the child's hydration status is the cornerstone to clinical management, regardless of whether the presenting complaint is vomiting or diarrhea (Table 73-1). Viral, bacterial, and other infectious organisms can cause gastroenteritis, and spread most commonly occurs by the fecal-to-oral route. Viral pathogens cause disease by invading tissue and altering the intestine's ability to absorb water and electrolytes. Bacterial pathogens cause diarrhea by producing enterotoxins and cytotoxins and by invading the intestine's mucosal absorptive surface. Dysentery occurs when bacteria invade the mucosa of the terminal ileum and colon, producing diarrhea with blood, mucus, or pus. Table 73-2 lists common infectious agents, clinical features, and treatments of diarrhea in children. Infants are at greater risk for rapid dehydration and hypoglycemia as are those with chronic illnesses, high-risk social situations, or malnutrition.

Acute gastroenteritis is a clinical diagnosis and is typically defined by the presence of three or more diarrheal stools in a 24-hour period. Because gastroenteritis induced dehydration is usually isotonic, serum electrolytes are not routinely helpful unless signs of severe dehydration are present or intravenous rehydration fluids will be administered. The exception is infants in the first 6 months of life, in whom significant sodium abnormalities may develop. Bedside glucose should be checked in all patients with altered mental status; hypoglycemia can develop rapidly in the setting of protracted vomiting or diarrhea in infants and toddlers. Stool cultures are reserved for cases in which the child has travelled to a high-risk country, is highly or persistently febrile, has > 10 stools in the previous 24 hours, or has blood in the stool. In the setting of a known outbreak of Escherichia coli O157:H7 consider stool cultures and blood tests to check for evidence of hemolysis, thrombocytopenia, and acute renal failure. The fecal leukocyte and guaiac tests have poor sensitivity and limited use.

Although diarrhea is the most prominent symptom of acute gastroenteritis in infants and children, other etiologies of diarrhea that may result in significant morbidity must be considered: bacterial colitis, Hirschsprung disease, partial obstruction, inflammatory bowel disease and hemolytic uremic syndrome. Acute appendicitis typically manifests with abdominal pain followed by vomiting associated with constipation, however, it may also cause diarrhea, particularly once the appendix has perforated (see Chapter 74 “Pediatric Abdominal Emergencies”).

Similarly, vomiting is a common and nonspecific presentation for other disease processes, such as otitis media, urinary tract infection, sepsis, malrotation, intussusception, increased intracranial pressure, metabolic acidosis, and drug or toxin ingestions. Consequently, isolated vomiting, though most often of viral origin, requires a careful and thoughtful evaluation before being diagnosed as acute gastroenteritis. Specific clinical findings, such as bilious or bloody vomitus, hematochezia, or abdominal pain, should trigger concerns for a disease process other than simple viral gastroenteritis.

Dehydration (Vomiting and/or Diarrhea)

1. Because most cases are self-limited, oral rehydration is generally all that is necessary. Vomiting is not a contraindication to oral rehydration; the key is to give small amounts of the solution frequently. Use of a commercially available oral rehydration solution (ORS) containing 45 to 60 mmol/L of sodium is recommended. Many other beverages traditionally suggested for children with vomiting and diarrhea, such as tea, juice, or sports drinks, are deficient in sodium and may provide excessive sugar, resulting in amplified fluid losses. Give 50 to 100 mL of ORS/kilogram of body weight, plus additional ORS to compensate for ongoing losses. Aim for about 1 ounce (30 mL) of ORS per kilogram of body weight per hour.

2. Administer intravenous or intraosseous isotonic crystalloid to children with severe dehydration, hemodynamic compromise, or when altered mental status precludes safe oral administration of fluid. Give normal saline as a 20 mL/kg bolus every 20 min until perfusion improves and urine output is adequate.

3. Treat hypoglycemia with 10% dextrose (5 mL/kg) in infants or 25% dextrose (2 mL/kg) in toddlers and older children.

Vomiting

1. Treat dehydration, hypoglycemia, and electrolyte abnormalities as above.

2. Consider ondansetron as an adjunct to oral rehydration therapy in children with persistent vomiting at a dose of 0.15 milligram/kilogram/dose. Oral dosing is preferred as the main objective is to support the success of oral rehydration. Dopamine receptor agonists such as promethazine are not recommend in children and are contraindicated in young children.

3. Most children can be discharged if they are tolerating oral rehydration, have adequate urine output, and ongoing fluid losses have been minimized. Continuation of a normal diet (including lactose-containing milk or formula) is recommended. Patients who cannot tolerate oral fluids, have significant ongoing losses, severe electrolyte abnormalities, or surgical abdominal processes require admission to the hospital.

Diarrhea

1. Treat dehydration and hypoglycemia as above.

2. Children with mild diarrhea who are not dehydrated may continue routine feedings. Do not withhold feedings > 4 hours in a dehydrated child or for any length of time in a child who is not dehydrated. There is no need to dilute formula because more than 80% of children with acute diarrhea can tolerate full-strength milk safely.

3. Antidiarrheal and antimotility agents such as loperamide, are not recommend in children and contraindicated in young children.

4. Antibiotics are unnecessary for the vast majority of children with acute gastroenteritis and may be associated with increased risk for hemolytic uremic syndrome. See Table 73-2 for specific treatment recommendations by pathogen.

5. All infants and children who appear toxic or have high-risk social situations, significant dehydration, significant ongoing fluid losses, altered mental status, inability to drink, or laboratory evidence of hemolytic anemia, thrombocytopenia, azotemia, or a significant dysnatremia should be admitted.

6. Children who respond to oral or intravenous hydration can be discharged. Instructions should be given to return to the emergency department or seek care with the primary physician if the child becomes unable to tolerate oral hydration, develops bilious vomiting, becomes less alert, or exhibits signs of dehydration, such as no longer wetting diapers. Dietary recommendations include a diet high in complex carbohydrates, lean meats, vegetables, fruits, and yogurt. Fatty foods and foods high in simple sugars should be avoided. The BRAT diet is discouraged because it does not provide adequate energy sources.