What are the criteria, workup, and treatment for mild, moderate, and severe Acute Gastroenteritis (AGE) in pediatric patients?

Classification and Management of Acute Gastroenteritis (AGE) in Pediatric Patients

Dehydration Severity Criteria

Mild Dehydration (3-5% fluid deficit)

• Clinical signs include: slightly dry mucous membranes, normal or slightly increased thirst, normal mental status, and normal vital signs 1, 2
• Skin turgor remains normal with no tenting 2
• Capillary refill remains normal (<2 seconds) 1
• Urine output is slightly decreased but still present 1

Moderate Dehydration (6-9% fluid deficit)

• Clinical signs include: loss of skin turgor with tenting when pinched, dry mucous membranes, increased thirst, and mild tachycardia 1, 2
• Mental status shows mild lethargy or irritability 1
• Capillary refill is delayed (2-3 seconds) 3
• Urine output is notably decreased 1
• Eyes may appear sunken 2

Severe Dehydration (≥10% fluid deficit)

• Critical signs include: severe lethargy or altered consciousness, prolonged skin tenting (>2 seconds), cool and poorly perfused extremities, and markedly decreased capillary refill 1, 2
• Rapid, deep breathing indicating metabolic acidosis 1
• Absent or minimal urine output 1
• Signs of shock including hypotension, weak pulse, and poor peripheral perfusion 2
• This constitutes a medical emergency requiring immediate intervention 1

Clinical Pearl: The most accurate assessment of dehydration is acute weight change when premorbid weight is known, though this is often unavailable 2. Prolonged skin retraction time, abnormal capillary refill, and rapid deep breathing are the most reliable clinical predictors 1, 3.

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Workup by Severity

Mild Dehydration Workup

• No laboratory testing is routinely required 2
• Clinical assessment alone is sufficient to guide management 1
• Assess for red flags: bloody diarrhea, high fever (>38.5°C), age <3 months, immunocompromised status, or recent international travel 2, 4

Moderate Dehydration Workup

• Laboratory testing is generally not required unless clinical features suggest complications 2
• Consider basic metabolic panel if there are concerns about electrolyte abnormalities or if the patient appears toxic 2
• Obtain stool studies (culture, microscopy) only if: bloody diarrhea present, fever with systemic toxicity, diarrhea persists >5 days, recent international travel, or immunocompromised status 2, 4
• Blood cultures if febrile and toxic-appearing 2

Severe Dehydration Workup

• Obtain serum electrolytes, BUN, creatinine, and venous blood gas to assess metabolic acidosis and guide fluid resuscitation 2, 3
• Low serum bicarbonate combined with clinical parameters helps confirm severe dehydration 3
• Stool culture and microscopy if bloody diarrhea or prolonged symptoms 2, 4
• Blood cultures if signs of sepsis or systemic toxicity 2
• Urinalysis if urinary symptoms present to rule out concurrent urinary tract infection 2

Important Caveat: Do not delay rehydration therapy while awaiting diagnostic test results—begin treatment immediately based on clinical assessment 2.

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Treatment by Severity

Mild Dehydration Treatment (3-5% deficit)

Primary Intervention:

• Administer 50 mL/kg of oral rehydration solution (ORS) over 2-4 hours 1
• Use low-osmolarity ORS formulations (preferred over sports drinks or juices) 2, 4

Administration Technique:

• Give 5-10 mL every 1-2 minutes using a teaspoon, syringe, or medicine dropper 1, 2
• Gradually increase volume as tolerated without triggering vomiting 1
• Critical pitfall to avoid: Never allow a thirsty, vomiting child to drink large volumes rapidly from a cup or bottle, as this perpetuates vomiting 1

Ongoing Loss Replacement:

• Replace each watery stool with 10 mL/kg of ORS 2
• Replace each vomiting episode with 2 mL/kg of ORS 1, 2

Nutritional Management:

• Continue breastfeeding throughout the illness on demand 1, 2, 4
• Resume full-strength formula or age-appropriate diet immediately after rehydration (within 4 hours) 1, 2
• Early feeding improves nutritional outcomes and is as safe as delayed feeding 1
• Avoid foods high in simple sugars (soft drinks, undiluted apple juice), high-fat foods, and caffeinated beverages 2

Monitoring:

• Reassess hydration status after 2-4 hours by examining skin turgor, mucous membrane moisture, mental status, activity level, and urine output 1, 2

Disposition:

• Most children with mild dehydration can be managed at home with caregiver education 2
• Provide ORS supply and clear instructions on small-volume, frequent administration technique 2

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Moderate Dehydration Treatment (6-9% deficit)

Primary Intervention:

• Administer 100 mL/kg of ORS over 2-4 hours 1, 2, 4
• Use the same small-volume, frequent administration technique as for mild dehydration (5-10 mL every 1-2 minutes) 1, 2

Ongoing Loss Replacement:

• Replace each watery stool with 10 mL/kg of ORS 1, 2
• Replace each vomiting episode with 2 mL/kg of ORS 1, 2

Adjunctive Antiemetic Therapy:

• Consider ondansetron if vomiting prevents adequate oral intake 1, 5
• Oral ondansetron reduces hospital admission rates and IV rehydration needs (RR 0.40 and 0.41, respectively) 5
• Ondansetron improves ORS tolerance and reduces need for IV therapy 1, 4

Alternative Route if Oral Fails:

• Use nasogastric tube administration at 15 mL/kg/hour as an alternative to IV therapy if the child cannot tolerate even small volumes orally but is not in shock 1, 2

Nutritional Management:

• Continue breastfeeding throughout 1, 2, 4
• Resume age-appropriate diet immediately after rehydration 1, 2
• Avoid restrictive diets or prolonged fasting 2

Monitoring:

• Monitor vital signs every 2-4 hours including capillary refill, skin turgor, mental status, and mucous membrane moisture 2
• Daily weights to track rehydration progress 2
• Reassess after 2-4 hours; if still dehydrated, reestimate deficit and restart rehydration 2

Escalation Criteria:

• Switch to IV therapy if: persistent vomiting despite ondansetron, altered mental status develops, signs of shock appear, or stool output exceeds 10 mL/kg/hour 1, 2, 4

Disposition:

• Many children with moderate dehydration can be managed in the emergency department or observation unit with close monitoring 2
• Admit if: failure of oral rehydration therapy, intractable vomiting, significant comorbidities, or caregiver unable to manage at home 2

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Severe Dehydration Treatment (≥10% deficit)

Immediate Intervention:

• This is a medical emergency—immediately switch to IV isotonic fluids (lactated Ringer's or normal saline) 1, 2, 4
• Oral rehydration is contraindicated in severe dehydration with shock or altered mental status 1, 2

IV Fluid Resuscitation Protocol:

• Administer rapid boluses of 20 mL/kg of isotonic crystalloid over 15-20 minutes 2
• Reassess after each bolus and repeat as needed until pulse, perfusion, and mental status normalize 2
• Continue IV rehydration until hemodynamically stable 2

Transition to Oral Rehydration:

• Once patient improves (normal vital signs, adequate perfusion, able to tolerate oral intake), transition to ORS to replace remaining deficit 2
• This typically occurs after initial resuscitation with 40-60 mL/kg IV fluids 2

Monitoring:

• Continuous cardiorespiratory monitoring 2
• Frequent vital signs (every 15-30 minutes initially) 2
• Monitor for signs of fluid overload, especially in patients receiving multiple boluses 2
• Serial electrolytes and blood gas to assess correction of acidosis 3

Adjunctive Therapy:

• IV ondansetron may reduce hospital admission rates if vomiting persists after initial stabilization (RR 0.21) 5

Nutritional Management:

• Resume feeding as soon as patient is hemodynamically stable and able to tolerate oral intake 1, 2
• Continue breastfeeding if applicable 1, 2

Disposition:

• All children with severe dehydration require hospital admission 2
• Admit to inpatient unit for continued IV therapy and monitoring 2
• Discharge criteria: tolerating oral intake, producing adequate urine, clinically rehydrated, and stable vital signs 2

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Critical Medications to AVOID

Contraindicated Agents

• Never give antimotility agents (loperamide) to any child <18 years with acute diarrhea—serious adverse events including ileus and deaths have been reported 1, 2, 4
• Do not use adsorbents, antisecretory drugs, or toxin binders—they do not reduce diarrhea volume or duration 2
• Metoclopramide has no role in gastroenteritis management and may worsen symptoms 2

Antibiotic Stewardship

• Do not give empiric antibiotics for uncomplicated watery diarrhea—most cases are viral and require only supportive care 1, 2, 4
• Consider antibiotics only if: bloody diarrhea with fever and systemic toxicity, diarrhea persists >5 days, stool culture confirms treatable pathogen (Shigella, Salmonella), or patient is immunocompromised with clinical sepsis 2, 4

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Special Considerations and Red Flags

High-Risk Populations Requiring Lower Threshold for Admission

• Infants <3 months of age 2
• Immunocompromised patients (HIV, malignancy, transplant recipients, immunosuppressive therapy) 2
• Patients with significant comorbidities 2

Absolute Indications for Hospital Admission

• Severe dehydration (≥10% deficit) or shock 2
• Altered mental status 1, 2
• Failure of oral rehydration therapy despite proper technique 1, 2
• Intractable vomiting despite ondansetron 2
• Absent bowel sounds (ileus) 1
• Bloody diarrhea with fever and systemic toxicity suggesting hemolytic uremic syndrome risk 2

Warning Signs Requiring Immediate Medical Reevaluation

• Persistent vomiting despite small-volume ORS administration 1
• Decreased urine output or no urine for >8 hours 1
• Increasing lethargy or irritability 1
• Bloody stools 1, 2
• High fever (>38.5°C) with systemic toxicity 2
• Failure to improve after initial rehydration attempt over 2-4 hours 1