What is the primary treatment for a patient with acute gastroenteritis and mild dehydration?

Treatment of Acute Gastroenteritis with Mild Dehydration

Oral rehydration solution (ORS) is the primary treatment for acute gastroenteritis with mild dehydration, administered at 50 mL/kg over 2-4 hours, with ongoing replacement of 10 mL/kg for each watery stool and 2 mL/kg for each vomiting episode. 1

Initial Assessment and Classification

Mild dehydration (3-5% fluid deficit) is characterized by: 1

• Increased thirst
• Slightly dry mucous membranes
• Normal to slightly decreased skin turgor 2
• Capillary refill time remains the most reliable clinical predictor of dehydration severity 2

Obtain baseline weight if possible, as acute weight change is the most accurate assessment of fluid deficit. 1

Rehydration Protocol

Administer low-osmolarity ORS (containing 50-90 mEq/L sodium) at 50 mL/kg over 2-4 hours for mild dehydration. 1, 2

Administration Technique

• Start with small volumes (5-10 mL every 1-2 minutes) using a spoon or syringe to prevent triggering vomiting 1
• Gradually increase volume as tolerated 1
• This small-volume, frequent approach successfully rehydrates >90% of patients without antiemetic medication 1

Ongoing Loss Replacement

• Replace 10 mL/kg ORS for each watery stool 1, 2
• Replace 2 mL/kg ORS for each vomiting episode 1, 2
• Continue ORS until diarrhea and vomiting resolve 1

Nutritional Management

Resume age-appropriate diet immediately during or after rehydration—do not delay feeding. 1, 3

• Continue breastfeeding on demand throughout the illness without interruption 1, 2
• Early refeeding promotes intestinal cell renewal and prevents nutritional deterioration 3
• Include starches, cereals, yogurt, fruits, and vegetables 2

Foods to Avoid

• Foods high in simple sugars (soft drinks, undiluted apple juice) as they worsen diarrhea through osmotic effects 1
• High-fat foods 2
• Caffeinated beverages (coffee, tea, energy drinks) as they stimulate intestinal motility and accelerate transit time 1

Adjunctive Pharmacotherapy

Ondansetron may be given if vomiting prevents adequate oral intake, as it reduces vomiting rate, improves ORS tolerance, and decreases need for IV rehydration. 1, 2, 4

Medications to Avoid

• Loperamide is absolutely contraindicated in children <18 years due to risk of respiratory depression and serious cardiac adverse reactions 1, 2
• In adults, loperamide may only be used after adequate rehydration and only if no fever or bloody stools present 3
• Antimotility agents, adsorbents, antisecretory drugs, and toxin binders are not effective and should not be used 1
• Metoclopramide has no role in gastroenteritis management and is explicitly not recommended 1

Monitoring and Reassessment

Reassess hydration status after 2-4 hours of rehydration therapy. 1, 2

Signs of Successful Rehydration

• Normal pulse and perfusion 3
• Improved mental status 3
• Moist mucous membranes 3
• Adequate urine output 3
• Ability to tolerate oral fluids without immediate vomiting 3

Criteria for Escalation to IV Therapy

If patient develops any of the following, transition to intravenous rehydration: 1

• Severe dehydration (≥10% fluid deficit)
• Altered mental status
• Failure of oral rehydration therapy despite proper technique
• Intractable vomiting despite ondansetron
• Absent bowel sounds (ileus) 1

Red Flags Requiring Immediate Medical Attention

Seek immediate care if patient develops: 1

• Bloody stools with fever and systemic toxicity
• Severe lethargy or altered consciousness
• Prolonged skin tenting (>2 seconds)
• Cool extremities with decreased capillary refill
• Rapid, deep breathing indicating acidosis
• High stool output (>10 mL/kg/hour)

Infection Control

• Practice proper hand hygiene after toilet use, before eating, and after handling soiled items 1
• Use gloves and gowns when caring for ill persons 1
• Clean and disinfect contaminated surfaces promptly 1
• Separate ill persons from well persons until at least 2 days after symptom resolution 1

Common Pitfalls to Avoid

• Do not delay rehydration while awaiting diagnostic testing—initiate ORS promptly 1
• Do not use sports drinks or apple juice as primary rehydration solutions for moderate to severe dehydration—they contain inadequate sodium and excessive osmolality 1, 2
• Do not restrict diet unnecessarily during or after rehydration 1
• Do not underestimate dehydration in elderly patients, who may not manifest classic signs and have higher mortality risk 1