Initial Treatment for Dehydrated 2-Year-Old with Vomiting and Diarrhea
Start oral rehydration solution (ORS) containing 50-90 mEq/L sodium at 50-100 mL/kg over 2-4 hours, depending on whether the child has mild (3-5% deficit) or moderate (6-9% deficit) dehydration. 1, 2
Immediate Assessment
First, determine the severity of dehydration through physical examination:
- Mild dehydration (3-5% fluid deficit): Increased thirst, slightly dry mucous membranes 2
- Moderate dehydration (6-9% fluid deficit): Loss of skin turgor, dry mucous membranes, decreased urine output 2, 3
- Severe dehydration (≥10% fluid deficit): Severe lethargy or altered consciousness, prolonged skin tenting, cool and poorly perfused extremities, rapid deep breathing—this is a medical emergency requiring immediate IV therapy 4, 2
The most reliable indicators are rapid deep breathing, prolonged skin retraction time, and decreased perfusion—more so than sunken fontanelle or absence of tears 2
Oral Rehydration Protocol
For Mild Dehydration (Most Likely Scenario)
- Administer 50 mL/kg of ORS over 2-4 hours 1, 2
- Start with small volumes using a teaspoon, syringe, or medicine dropper (e.g., one teaspoon initially) 1, 3
- Gradually increase the amount as tolerated 1
- Use commercially available ORS such as Pedialyte, CeraLyte, or Enfalac Lytren 3
For Moderate Dehydration
- Increase the initial ORS volume to 100 mL/kg over 2-4 hours 1, 2, 3
- Follow the same gradual administration technique 3
- Research demonstrates that ORT is as effective as IV therapy for moderate dehydration, with faster initiation time (20 minutes vs 41 minutes) and lower hospitalization rates (31% vs 49%) 5
A critical pitfall: Children who tolerate at least 25 mL/kg of ORS during the initial observation period have an 80% success rate with home oral rehydration, while those tolerating less than 11 mL/kg are more likely to fail outpatient management 6
Replace Ongoing Losses
During rehydration, you must replace continued losses:
- Give 50-100 mL of ORS after each diarrheal stool for a 2-year-old 1, 3
- Give 2 mL/kg of ORS for each vomiting episode 3
- If losses can be measured precisely, provide 1 mL of ORS for each gram of diarrheal stool 1
Reassessment at 2-4 Hours
After the initial rehydration period:
- If rehydrated: Progress to maintenance therapy and resume feeding 1, 2
- If still dehydrated: Reestimate the fluid deficit and restart rehydration therapy 1, 3
- Monitor skin turgor, mucous membrane moisture, mental status, and stool frequency 3
Feeding During and After Rehydration
- Continue breastfeeding on demand throughout the illness if the child is breastfed 1, 2, 3
- Resume full-strength, lactose-free or lactose-reduced formula immediately upon rehydration if bottle-fed 1, 2
- Offer age-appropriate foods every 3-4 hours as tolerated once appetite returns 3
- There is no justification for "resting the bowel" through fasting 1, 2
Important caveat: True lactose intolerance (indicated by worsening diarrhea upon reintroduction of lactose-containing formula) requires temporary lactose reduction, but low stool pH or reducing substances alone without clinical symptoms do not indicate lactose intolerance 1
When to Switch to IV Therapy
Immediately initiate IV rehydration if:
- Severe dehydration with shock or near-shock (≥10% fluid deficit, altered mental status) 4, 2
- Failure of ORS therapy after appropriate trial 3
- Persistent severe vomiting preventing oral intake 4
For severe cases, give 20 mL/kg boluses of Ringer's lactate or normal saline until pulse, perfusion, and mental status normalize, which may require two IV lines 1, 4
Antiemetic Consideration
Ondansetron can be administered to facilitate oral rehydration once adequate assessment is complete, particularly if vomiting is limiting ORS intake 4