What treatment is recommended for diarrhea and vomiting in patients with potential underlying medical conditions?

Treatment of Diarrhea and Vomiting

Oral rehydration solution (ORS) is the definitive first-line treatment for diarrhea and vomiting in patients with mild to moderate dehydration, regardless of age or underlying medical conditions. 1, 2, 3

Immediate Rehydration Strategy

Oral Rehydration Solution Administration

• Administer reduced osmolarity ORS as first-line therapy for all patients with mild to moderate dehydration (3-9% fluid deficit). 1, 2, 3
• Start with small volumes (5-10 mL every 1-2 minutes) using a spoon or syringe, especially when vomiting is present. 3, 4
• Gradually increase volume as tolerated without triggering additional vomiting. 3
• Continue ORS until clinical dehydration is corrected, then replace ongoing losses with 10 mL/kg for each watery stool and 2 mL/kg for each vomiting episode. 1, 2, 3
• Most fluid given during vomiting episodes is actually retained and benefits the patient, even if it appears large amounts are vomited. 4
• If vomiting occurs, wait 10 minutes then resume ORS more slowly. 4

When to Escalate to Intravenous Therapy

• Reserve IV fluids exclusively for severe dehydration (≥10% fluid deficit), shock, altered mental status, or failure of oral rehydration after appropriate trial. 1, 2, 3
• Use isotonic fluids (lactated Ringer's or normal saline) until pulse, perfusion, and mental status normalize. 1, 2
• Transition back to ORS once patient stabilizes to replace remaining deficit. 1, 2

Nutritional Management

• Resume age-appropriate diet immediately during or after rehydration—do not withhold food. 1, 2, 3
• Continue breastfeeding throughout the illness without interruption. 1, 2, 3
• Early refeeding prevents malnutrition and may reduce stool output. 1
• Avoid foods high in simple sugars (soft drinks, undiluted apple juice), high-fat foods, and caffeinated beverages as these worsen diarrhea. 3

Pharmacological Considerations

Antiemetics

• Ondansetron may be given to children >4 years and adults to facilitate oral rehydration when vomiting is significant. 1, 2, 3
• Antiemetics like chlorpromazine should not be used as they cause drowsiness and interfere with ORS continuation. 4
• Never use metoclopramide in gastroenteritis—it is ineffective and potentially harmful. 3

Antimotility Agents

• Loperamide is absolutely contraindicated in all children <18 years with acute diarrhea due to risk of serious adverse events including ileus and death. 1, 2, 3
• Loperamide may be given to immunocompetent adults with acute watery diarrhea once adequately hydrated, but avoid in inflammatory or febrile diarrhea due to toxic megacolon risk. 2, 3

Probiotics

• Probiotics may be offered to reduce symptom severity and duration in immunocompetent patients, reducing diarrhea duration by approximately 25 hours. 1, 2, 3

Antimicrobials

• Empiric antimicrobials are NOT indicated for typical viral gastroenteritis without recent international travel. 1, 2
• Consider antibiotics only for specific high-risk features: fever ≥38.5°C with sepsis signs, bloody diarrhea with presumptive shigellosis, immunocompromised state, or ill-appearing infants <3 months. 1, 2
• Never use antimicrobials in STEC O157 or Shiga toxin 2-producing E. coli infections due to increased risk of hemolytic uremic syndrome. 2

Assessment of Dehydration Severity

Clinical Signs to Evaluate

• Mild dehydration (3-5%): Slightly dry mucous membranes, normal vital signs. 3
• Moderate dehydration (6-9%): Loss of skin turgor with tenting, dry mucous membranes, decreased urine output. 3
• Severe dehydration (≥10%): Severe lethargy/altered consciousness, prolonged skin tenting >2 seconds, cool extremities with poor perfusion, rapid deep breathing indicating acidosis. 3
• The most reliable clinical predictors are prolonged skin retraction time, abnormal capillary refill, and rapid deep breathing. 3

Special Populations Requiring Lower Threshold for Concern

• Elderly patients (≥65 years) have higher hospitalization and mortality rates—use lower threshold for IV therapy and admission. 2
• Immunocompromised patients (HIV, transplant recipients, malignancy, immunosuppressive therapy) require aggressive management. 2
• Infants <3 months warrant careful consideration for admission due to higher risk of severe dehydration. 2

Red Flags Requiring Immediate Medical Evaluation

• Altered mental status or severe lethargy. 3
• Prolonged skin tenting >2 seconds. 3
• Cool extremities with decreased capillary refill. 3
• Bloody stools with fever and systemic toxicity. 1, 2
• Persistent vomiting despite small-volume ORS administration. 3
• Absent bowel sounds (absolute contraindication to oral rehydration). 3
• Development of whitish/acholic stools suggesting biliary obstruction or hepatitis. 1

Critical Pitfalls to Avoid

• Do not delay rehydration while awaiting diagnostic testing—initiate ORS immediately. 3
• Do not use inappropriate fluids like sports drinks or apple juice as primary rehydration solutions. 3
• Do not withhold food during or after rehydration. 1, 2, 3
• Do not use adsorbents, antisecretory drugs, or toxin binders—they are ineffective. 3
• Do not dismiss whitish stools as part of viral gastroenteritis—this requires urgent hepatobiliary evaluation. 1
• Do not underestimate dehydration in elderly patients who may not manifest classic signs. 2

Infection Control

• Practice hand hygiene after toilet use, before eating, and before food preparation. 1, 3
• Use gloves and gowns when caring for patients with diarrhea. 3
• Clean and disinfect contaminated surfaces promptly. 3
• Separate ill persons from well persons until at least 2 days after symptom resolution. 3