What is the initial management for a patient presenting with acute gastroenteritis?

Initial Management of Acute Gastroenteritis

Oral rehydration solution (ORS) is the first-line treatment for patients with mild to moderate dehydration from acute gastroenteritis, and should be initiated immediately using low-osmolarity formulations administered in small, frequent volumes. 1

Immediate Assessment of Hydration Status

Evaluate dehydration severity through specific clinical signs rather than waiting for laboratory confirmation 1, 2:

• Mild dehydration (3-5% fluid deficit): Slightly decreased skin turgor, normal mental status, moist mucous membranes 1
• Moderate dehydration (6-9% fluid deficit): Loss of skin turgor with tenting, dry mucous membranes, decreased urine output, tachycardia 1, 2
• Severe dehydration (≥10% fluid deficit): Severe lethargy or altered consciousness, prolonged skin tenting (>2 seconds), cool extremities with poor perfusion, rapid deep breathing indicating acidosis 1, 2

The most reliable clinical predictors are prolonged skin retraction time, abnormal capillary refill, and rapid deep breathing; acute weight change is most accurate when premorbid weight is known 1, 3.

Rehydration Protocol by Severity

Mild to Moderate Dehydration

Administer low-osmolarity ORS at 50-100 mL/kg over 2-4 hours 1, 2:

• 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
• Replace ongoing losses continuously: 10 mL/kg ORS for each watery stool and 2 mL/kg for each vomiting episode 1, 2
• Use commercially available low-osmolarity formulations (e.g., Pedialyte, CeraLyte); avoid apple juice, sports drinks, or soft drinks as they have inappropriate osmolarity and can worsen osmotic diarrhea 1, 2

If the patient refuses oral intake, nasogastric administration of ORS may be considered 1, 2.

Severe Dehydration

Administer isotonic intravenous fluids (lactated Ringer's or normal saline) at 20 mL/kg over 30 minutes 2:

• Continue IV rehydration until pulse, perfusion, and mental status normalize 1, 2
• Transition to ORS to replace remaining deficit once the patient improves 1
• Reserve IV therapy for patients with severe dehydration, shock, altered mental status, failure of oral rehydration therapy, or ileus 1, 2

Nutritional Management

Resume age-appropriate diet during or immediately after rehydration rather than fasting 1, 2:

• Continue breastfeeding throughout the diarrheal episode in infants 1, 2
• Early refeeding reduces severity and duration of illness 1
• Avoid foods high in simple sugars (soft drinks, undiluted apple juice), high-fat foods, and caffeinated beverages as they can exacerbate diarrhea through osmotic effects 1

Pharmacological Management

Antiemetics

Ondansetron may be administered to children >4 years and adolescents with significant vomiting to facilitate oral rehydration tolerance (dose: 0.15 mg/kg per dose) 1, 2. This can decrease the need for intravenous fluids and hospitalization 4, 5.

Antimotility Agents

Loperamide is absolutely contraindicated in children <18 years with acute diarrhea 1, 6. In immunocompetent adults with acute watery diarrhea, loperamide may be given once adequately hydrated (initial dose 4 mg, then 2 mg after each loose stool, maximum 16 mg/day) 1, 2, 6. Avoid antimotility agents in cases of bloody diarrhea, fever, or suspected inflammatory diarrhea 2, 6.

Antibiotics

Antimicrobial agents have limited usefulness since viral agents are the predominant cause 1. Consider antibiotics only in specific cases: bloody diarrhea with fever, recent antibiotic use (test for Clostridioides difficile), exposure to certain pathogens, recent foreign travel, or immunodeficiency 1.

Adjunctive Therapies

Probiotics may reduce symptom severity and duration in both adults and children 1. Zinc supplementation reduces diarrhea duration in children 6 months to 5 years in areas with high zinc deficiency prevalence or in malnourished children 1.

Infection Control Measures

Practice proper hand hygiene after using toilet, changing diapers, before and after food preparation, and before eating 1, 2:

• Use gloves and gowns when caring for patients with diarrhea 1
• Clean and disinfect contaminated surfaces promptly 1
• Separate ill persons from well persons until at least 2 days after symptom resolution 1

Critical Pitfalls to Avoid

• Do not delay rehydration while awaiting diagnostic testing; initiate ORS immediately 1
• Do not use inappropriate fluids (apple juice, sports drinks) as primary rehydration solutions for moderate to severe dehydration 1, 3
• Do not administer antimotility drugs to children or in cases of bloody diarrhea 1, 6
• Do not unnecessarily restrict diet during or after rehydration; early refeeding improves outcomes 1, 2
• Do not underestimate dehydration in elderly patients, who may not manifest classic signs and have higher mortality risk 1

Indications for Hospitalization

Admit patients with 1:

• Severe dehydration (≥10% fluid deficit) or signs of shock
• Failure of oral rehydration therapy after 2-4 hours of appropriate ORS administration
• Altered mental status or intractable vomiting despite antiemetics
• Significant comorbidities (immunocompromised, elderly ≥65 years, infants <3 months)
• Bloody diarrhea with fever and systemic toxicity suggesting bacterial dysentery

Reassessment

Reassess hydration status after 2-4 hours of ORS administration 1. If still dehydrated, reestimate deficit and restart rehydration protocol 1. Monitor vital signs, capillary refill, skin turgor, mental status, and mucous membrane moisture to assess for worsening dehydration 1.