What is the best course of treatment for a 7-year-old male presenting with acute onset of vomiting and diarrhea, who experienced an episode of syncope (fainting) after emesis (vomiting)?

Management of 7-Year-Old with Acute Gastroenteritis and Post-Emetic Syncope

This child requires immediate assessment for dehydration severity and cardiac causes of syncope, with oral rehydration therapy as first-line treatment if dehydration is mild-to-moderate and no cardiac red flags are present.

Immediate Assessment Priorities

Evaluate Dehydration Severity

The syncope following vomiting most likely represents vasovagal response secondary to dehydration, but you must first rule out dangerous causes and quantify fluid deficit 1:

• Mild dehydration (3-5% deficit): Increased thirst, slightly dry mucous membranes 2
• Moderate dehydration (6-9% deficit): Loss of skin turgor, dry mucous membranes, decreased urine output, rapid deep breathing, prolonged skin retraction time, decreased perfusion 1
• Severe dehydration (>9% deficit): Altered mental status, shock, poor perfusion requiring immediate IV access 3

Screen for Cardiac Syncope Red Flags

While most pediatric syncope is benign, cardiac causes carry mortality risk and must be excluded 4, 5:

• Concerning features: Syncope during exertion, lack of prodromal symptoms, syncope in supine position, family history of sudden death, known cardiac disease 5
• Obtain ECG on all children with syncope to exclude arrhythmias and channelopathies 5
• If cardiac red flags present, this child needs emergency cardiology evaluation regardless of gastroenteritis 4

Rehydration Protocol

For Mild-to-Moderate Dehydration (Most Likely Scenario)

Oral rehydration solution (ORS) is the first-line therapy 3, 1:

• Dose: 50-100 mL/kg over 3-4 hours for moderate dehydration 3, 1
• Administration technique for vomiting: Start with small frequent volumes (5 mL every minute) using spoon or syringe 3
• Replace ongoing losses: 60-120 mL ORS for each diarrheal stool or vomiting episode 1
• Appropriate ORS products: Pedialyte, CeraLyte, or Enfalac Lytren—NOT sports drinks, juice, or soda 3, 1

Managing Persistent Vomiting

Consider ondansetron to facilitate oral rehydration 3:

• Dose: 8 mg sublingual every 4-6 hours (for children >4 years) 3
• Benefit: Reduces immediate need for IV rehydration and hospitalization 3
• Caveat: May increase stool volume and can prolong QTc interval—obtain baseline ECG if using 3
• Ondansetron helps children tolerate ORS when vomiting is the primary barrier to oral intake 3

When to Escalate to IV Therapy

Switch to intravenous isotonic fluids (lactated Ringer's or normal saline) if 3, 1:

• Severe dehydration with altered mental status or shock
• Failure of ORS therapy after appropriate trial
• Intractable vomiting preventing oral intake
• Ileus present

Administer 20 mL/kg boluses until pulse, perfusion, and mental status normalize 3

Dietary Management

Resume age-appropriate diet immediately after rehydration 3:

• Continue usual diet during illness—starches, cereals, yogurt, fruits, vegetables 3
• Avoid foods high in simple sugars and fats 3
• No need for BRAT diet or dairy restriction unless lactose intolerance develops 3

Medications to AVOID

Do not use antimotility agents (loperamide) in children <18 years 3:

• Strong contraindication due to risk of ileus, lethargy, and reported deaths in young children 3
• Antibiotics not indicated for acute watery diarrhea without dysentery, high fever, or duration >5 days 3

Disposition and Follow-Up

Return Precautions

Instruct parents to return immediately if 3:

• Child becomes irritable or lethargic
• Decreased urine output persists
• Intractable vomiting develops
• Recurrent syncope occurs
• Any cardiac symptoms emerge (chest pain, palpitations, exercise intolerance)

Outpatient Management

If dehydration is mild and no cardiac concerns exist, this child can be managed at home with 3, 1:

• ORS replacement of ongoing losses
• Close monitoring of hydration status
• Primary care follow-up within 24-48 hours if symptoms persist

Critical Pitfall to Avoid

The syncope episode demands you rule out cardiac causes before attributing it solely to dehydration 4, 5. While post-emetic vasovagal syncope is common and benign, missing a cardiac arrhythmia or structural heart disease carries significant mortality risk. The ECG is non-negotiable in this scenario 5. If the ECG is normal and the clinical picture fits simple dehydration with vasovagal syncope (prodromal symptoms, occurred immediately after vomiting, rapid recovery), proceed confidently with rehydration therapy 4, 5.