What is the treatment for a 3-month-old infant with vomiting and diarrhea for 3 weeks?

Management of a 3-Month-Old Infant with 3 Weeks of Vomiting and Diarrhea

Immediate Assessment Priority

This 3-month-old infant with 3 weeks of persistent vomiting and diarrhea requires immediate assessment for dehydration severity and consideration of underlying causes beyond typical acute gastroenteritis, as symptoms lasting this long warrant investigation for chronic etiologies. 1, 2

Clinical Assessment of Dehydration

Evaluate dehydration severity using these specific clinical parameters:

• Capillary refill time is the most reliable predictor of dehydration in this age group 1
• Examine skin turgor (prolonged tenting >2 seconds indicates severe dehydration) 3
• Assess mucous membranes for dryness 3
• Check mental status (lethargy or altered consciousness indicates severe dehydration) 3
• Evaluate perfusion of extremities 3
• Obtain weight measurement immediately to calculate fluid deficit and monitor treatment response 3, 2

Dehydration Categories:

• Mild: 3-5% fluid deficit 3, 1
• Moderate: 6-9% fluid deficit 3, 1
• Severe: ≥10% fluid deficit with shock or near-shock 3, 1

Rehydration Protocol

For Severe Dehydration (≥10% deficit):

• Administer 20 mL/kg boluses of Ringer's lactate or normal saline IV immediately until pulse, perfusion, and mental status normalize 1, 4
• This constitutes a medical emergency requiring immediate IV access (may need two IV lines or alternate sites like intraosseous) 3
• Once circulation is restored, transition to oral rehydration solution (ORS) for remaining deficit 1

For Moderate Dehydration (6-9% deficit):

• Administer 100 mL/kg of ORS over 2-4 hours 3, 1
• Consider nasogastric administration if oral intake is not tolerated 1

For Mild Dehydration (3-5% deficit):

• Administer 50 mL/kg of ORS over 2-4 hours 3, 1

Technique for Vomiting Infant:

• Give small volumes (5 mL) every 1-2 minutes using a spoon or syringe, gradually increasing as tolerated 3, 4
• Simultaneous correction of dehydration often lessens vomiting frequency 3
• Common pitfall: Allowing a thirsty infant to drink large volumes ad libitum worsens vomiting 4

Ongoing Loss Replacement

• Replace 10 mL/kg of ORS for each watery stool 3, 1
• Replace 2 mL/kg of ORS for each vomiting episode 3, 1
• Continue replacement throughout rehydration and maintenance phases 3

Nutritional Management

• If breastfed, continue nursing on demand without interruption throughout the entire episode 3, 4
• For bottle-fed infants, resume full-strength lactose-free or lactose-reduced formula immediately upon rehydration 3, 1
• If lactose-free formula is unavailable, use full-strength lactose-containing formula under supervision 3
• Do not delay feeding—there is no justification for "bowel rest" 1
• Avoid foods high in simple sugars and fats 3, 4

Critical Considerations for 3-Week Duration

Important caveat: The 3-week duration is atypical for acute viral gastroenteritis and warrants additional evaluation:

• Consider antibiotics when watery diarrhea lasts >5 days 3, 4
• Stool cultures are indicated for persistent diarrhea to identify treatable pathogens 3, 4
• Evaluate for lactose intolerance (exacerbation of diarrhea upon lactose introduction) 3
• Consider underlying conditions causing chronic diarrhea in this age group 2

Absolutely Contraindicated Interventions

• Antimotility drugs (loperamide) are absolutely contraindicated in all children <18 years due to risks of respiratory depression and serious cardiac adverse reactions 1, 4
• Do not use cola drinks or soft drinks for rehydration—they contain inadequate sodium and excessive osmolality that worsens diarrhea 4, 5
• Avoid hypotonic solutions for initial rehydration in severe dehydration 1

Monitoring and Red Flags

• Reassess hydration status after 2-4 hours of rehydration 3, 1
• If still dehydrated, reestimate fluid deficit and restart rehydration 3

Return immediately if:

• Bloody diarrhea (dysentery) develops 4
• Intractable vomiting prevents oral rehydration 3, 4
• High stool output (>10 mL/kg/hour) persists 1, 4
• Lethargy, irritability, or decreased urine output occurs 3, 4
• Condition worsens or fever develops 1

Laboratory Testing

• Serum electrolytes are indicated when clinical signs suggest abnormal sodium or potassium concentrations 3
• Stool cultures are indicated given the 3-week duration to identify specific pathogens requiring treatment 3, 4
• Laboratory studies are rarely needed for typical acute diarrhea but are appropriate here given chronicity 3