How should fluid management be performed in a child with acute diarrhoea and moderate or severe dehydration according to WHO guidelines?

Fluid Management in Pediatric Patients with Moderate and Severe Dehydration

Initial Assessment

Assess dehydration severity using clinical signs: moderate dehydration (6-9% fluid deficit) presents with loss of skin turgor, skin tenting when pinched, and dry mucous membranes, while severe dehydration (≥10% fluid deficit) presents with severe lethargy or altered consciousness, prolonged skin tenting >2 seconds, cool poorly perfused extremities, decreased capillary refill, and rapid deep breathing indicating acidosis. 1, 2

Key assessment points:

• Obtain body weight immediately to establish baseline and calculate fluid deficit 1, 2
• Capillary refill time is the most reliable predictor of dehydration severity 2
• Rapid deep breathing, prolonged skin retraction time, and decreased perfusion are more reliable than sunken fontanelle or absent tears 1, 2

Rehydration Protocol by Severity

Moderate Dehydration (6-9% Fluid Deficit)

Administer 100 mL/kg of oral rehydration solution (ORS) containing 50-90 mEq/L sodium over 2-4 hours. 1, 2

Implementation approach:

• Start with small volumes (one teaspoon) using a teaspoon, syringe, or medicine dropper 1
• Gradually increase the amount as tolerated 1
• If oral intake is not tolerated, consider nasogastric administration 2
• Reassess hydration status after 2-4 hours 1, 2

Severe Dehydration (≥10% Fluid Deficit)

Severe dehydration constitutes a medical emergency requiring immediate intravenous rehydration with 20 mL/kg boluses of Ringer's lactate or normal saline until pulse, perfusion, and mental status normalize. 1, 2

Critical management steps:

• Administer IV boluses immediately without delay 1, 2
• Monitor continuously for improvement in vital signs and perfusion 2
• Once circulation is restored, transition to ORS for the remaining fluid deficit 2
• Balanced crystalloid solutions (Ringer's lactate) likely result in slightly reduced hospital stay compared to 0.9% saline and probably reduce risk of hypokalaemia 3

Ongoing Loss Replacement During Rehydration

Replace ongoing losses with 10 mL/kg of ORS for each watery stool and 2 mL/kg of ORS for each vomiting episode. 2, 4

Alternative weight-based approach:

• For children <10 kg: administer 60-120 mL ORS per diarrheal stool (maximum ~500 mL/day) 4
• For children >10 kg: administer 120-240 mL ORS per diarrheal stool (maximum ~1 L/day) 4

Nutritional Management During Rehydration

Resume age-appropriate diet immediately upon rehydration without any delay for "bowel rest." 2

Specific feeding recommendations:

• Continue breastfeeding throughout the entire episode without interruption 2, 5
• For bottle-fed infants, resume full-strength formula immediately upon rehydration 5
• Include starches, cereals, yogurt, fruits, and vegetables 2
• Avoid foods high in simple sugars and fats during rehydration 2

Monitoring and Reassessment

Reassess hydration status after 2-4 hours of rehydration therapy. 1, 2

Decision algorithm after reassessment:

• If rehydrated: transition to maintenance phase with ongoing loss replacement 2
• If still dehydrated: reestimate fluid deficit and restart rehydration therapy 1

Return immediately if:

• Many watery stools continue or high stool output (>10 mL/kg/hour) persists 2
• Increased thirst or sunken eyes appear 2
• Condition worsens or bloody diarrhea develops 2
• Intractable vomiting occurs 2

Critical Pitfalls to Avoid

Antimotility drugs (loperamide) are absolutely contraindicated in all children <18 years due to risks of respiratory depression and serious cardiac adverse reactions. 2

Additional contraindications:

• Do not use cola drinks or soft drinks for rehydration as they contain inadequate sodium and excessive osmolality that worsens diarrhea 2, 4
• Do not use hypotonic solutions for initial rehydration in severe dehydration 2
• Do not rely solely on sunken fontanelle or absent tears for dehydration assessment 2
• Do not routinely order laboratory tests for mild-moderate dehydration without specific clinical indications 2

Nuances in Evidence

The evidence strongly supports ORS as first-line therapy for moderate dehydration, with research showing that children who tolerate at least 25 mL/kg of ORS in the emergency department setting are likely to succeed with home oral rehydration 6. For severe dehydration requiring IV therapy, balanced crystalloid solutions like Ringer's lactate likely result in slightly shorter hospital stays (mean difference -0.35 days) and probably reduce hypokalaemia risk compared to 0.9% saline, though the evidence on mortality is very uncertain 3. The guidelines are consistent across CDC, WHO, and AAP recommendations regarding volume and timing of rehydration 1, 2.