What is the recommended fluid management approach for a patient with dehydration?

Fluid Management for Moderate Dehydration

For moderate dehydration (6-9% fluid deficit), administer oral rehydration solution (ORS) at 100 mL/kg over 2-4 hours, using commercially available reduced-osmolarity formulations containing 50-90 mEq/L sodium such as Pedialyte, CeraLyte, or Enfalyte. 1, 2

Clinical Assessment

Before initiating treatment, assess the degree of dehydration by examining:

• Skin turgor and capillary refill time (prolonged skin retraction >2 seconds and capillary refill 2-3 seconds indicate moderate dehydration) 1, 3
• Mucous membrane dryness (dry mucous membranes are characteristic of moderate dehydration) 2
• Mental status and perfusion (decreased perfusion without shock suggests moderate volume depletion) 1, 3
• Rapid deep breathing (more reliable than sunken fontanelle or absent tears) 1, 2

Initial Rehydration Phase

Oral Rehydration Solution Administration

Start with small volumes using a teaspoon, syringe, or medicine dropper, then gradually increase as tolerated. 3 This approach is particularly important for patients with vomiting. 1, 3

• For children with vomiting: Begin with 5-10 mL every 1-2 minutes, progressively increasing the amount 1, 3
• If unable to drink but not in shock: Consider nasogastric administration at 15 mL/kg/hour 3
• Total rehydration volume: 100 mL/kg over 2-4 hours for moderate dehydration 1, 2, 3

Acceptable ORS Formulations

Use only commercially available reduced-osmolarity ORS (total osmolarity <250 mmol/L) containing 50-90 mEq/L sodium. 1, 2 Acceptable products include:

• Pedialyte 2, 3
• CeraLyte 2
• Enfalyte/Infalyte 2

Critical pitfall: Do not use apple juice, Gatorade, sports drinks, or commercial soft drinks for rehydration—these have inappropriate osmolality and electrolyte composition. 1, 2, 3

Replacement of Ongoing Losses

While rehydration is ongoing, replace continuing losses from diarrhea and vomiting:

• 10 mL/kg ORS for each watery stool 1
• 2 mL/kg ORS for each vomiting episode 1
• Alternative approach for children <10 kg: 60-120 mL per episode 3
• Alternative approach for children >10 kg: 120-240 mL per episode 3

Nutritional Management During Rehydration

Resume age-appropriate normal diet as soon as appetite returns—typically within 3-4 hours after rehydration begins. 1, 2, 3 The outdated practice of "resting the bowel" through fasting should be avoided. 1, 2

• Breastfed infants: Continue nursing on demand throughout the illness 1, 2, 3
• Bottle-fed infants: Use full-strength, lactose-free, or lactose-reduced formulas immediately upon rehydration 1, 2
• Previously lactose-containing formula: Can be tolerated in most instances without dilution 4

Reassessment and Monitoring

After 2-4 hours of rehydration, reassess hydration status by evaluating:

• Mental status 1, 2, 3
• Skin turgor 1, 3
• Mucous membrane moisture 1, 3
• Urine output (goal >1 mL/kg/hour) 3
• Vital signs 1, 3

If rehydration is successful: Progress to maintenance phase with continued ORS for ongoing losses until diarrhea and vomiting resolve 4, 2

If dehydration persists: Reestimate the fluid deficit and restart rehydration therapy 1, 3

When to Switch to Intravenous Therapy

Transition to IV rehydration with isotonic fluids (lactated Ringer's or normal saline) if any of the following develop:

• Severe dehydration, shock, or altered mental status 4, 2, 3
• ORS therapy failure (approximately 4% of patients) 4, 2
• Paralytic ileus 4, 2
• Inability to tolerate oral or nasogastric intake 2
• Ketonemia preventing oral tolerance 4

For severe dehydration requiring IV therapy, administer 20 mL/kg boluses of isotonic crystalloid until pulse, perfusion, and mental status normalize, then transition back to ORS for remaining deficit replacement. 2, 3

Evidence Strength

A meta-analysis of 17 randomized controlled trials involving 1,811 pediatric patients demonstrated no clinically important differences between ORS and IV therapy in rehydration success, weight gain, electrolyte abnormalities, or diarrhea duration, supporting ORS as the safer first-line approach with lower complication rates (phlebitis occurs more with IV therapy). 4, 2

Critical Contraindications

Do not administer antimotility agents (loperamide) to any pediatric patient with acute diarrhea—these are contraindicated in children under 18 years. 1, 3