What fluid dose is recommended for dehydration?

Fluid Management for Dehydration

For dehydration lasting 2 days, oral rehydration solution (ORS) should be administered at 50-100 mL/kg over 2-4 hours for mild dehydration and 100 mL/kg over 2-4 hours for moderate dehydration, followed by ongoing replacement of 10 mL/kg after each loose stool. 1

Assessment of Dehydration Severity

Before initiating fluid therapy, assess the degree of dehydration:

• Mild (3-5%): Minimal electrolyte disturbances, thirst, slightly dry mucous membranes
• Moderate (6-9%): Higher risk of electrolyte abnormalities, decreased skin turgor, dry skin
• Severe (≥10%): Severe electrolyte disturbances, lethargy, prolonged skin retraction, cold extremities 1

Initial Rehydration Protocol

Mild to Moderate Dehydration

• Mild dehydration: 50 mL/kg of ORS over 2-4 hours
• Moderate dehydration: 100 mL/kg of ORS over 2-4 hours 1

Severe Dehydration

• Immediate IV rehydration with bolus doses of 20 mL/kg of lactated Ringer's solution or normal saline
• Continue with oral rehydration when consciousness normalizes
• For severely dehydrated patients, 60-100 mL/kg of 0.9% saline should be given in the first 2-4 hours to restore circulation 1, 2

Ongoing Fluid Management

After initial rehydration:

• Provide 10 mL/kg of ORS after each loose stool
• Give 2 mL/kg after each episode of vomiting 1

For children:

• Less than 2 years old: 50-100 mL of ORS after each stool
• Older children: 100-200 mL after each stool
• Adults: As much as desired 3

Composition of Optimal ORS

The World Health Organization recommends ORS with:

• Sodium: 65-70 mEq/L
• Glucose: 75-90 mmol/L
• Potassium: 20 mEq/L 1

Maintenance Fluids for Children

For pediatric patients with severe dehydration, calculate maintenance fluids using the Holliday-Segar method:

• First 10 kg: 100 mL/kg/day
• Second 10 kg: 50 mL/kg/day
• Each additional kg: 20 mL/kg/day 1

Important Clinical Considerations

1. Monitor hydration status every 2-4 hours and track weight daily 1

2. Continue feeding during rehydration:

   • Breastfed infants should continue breastfeeding on demand
   • Formula-fed infants may need lactose-free formulas after rehydration
   • Offer food every 3-4 hours for young children 3, 1

3. Avoid inappropriate fluids such as:

   • Sports drinks
   • Juices
   • Soft drinks
   • High-osmolality beverages 4

4. Warning signs requiring immediate medical attention:

   • Failure to improve within 48 hours
   • Worsening dehydration despite therapy
   • Persistent vomiting
   • Decreased urine output
   • Lethargy or altered mental status 1

Practical Implementation Tips

• An ORS tolerance test can help determine if a patient can be managed at home. Patients who can tolerate approximately 25 mL/kg of ORS during a 2-4 hour observation period are more likely to succeed with home management 5

• For patients with hypernatremic dehydration, slower correction over 2-3 days using 5% dextrose in 0.2% saline with 20 mEq/L KCl is recommended to avoid cerebral edema 2

• In resource-limited settings, rapid IV rehydration (2-3 hours) followed by early oral rehydration has been shown to be effective and safe 6