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Pediatric Hypotonic Dehydration

See Also
1. Pediatric Dehydration Management
Definition
1. Pediatric Dehydration
2. Serum Sodium < 130
Example Case
1. Weight: 35 kg Child
2. Dehydration: 10%
3. Serum Sodium: 120
Calculate Replacement and Replace Phase 1 Fluids
1. Approach as per Pediatric Dehydration Management
2. Deficit: 3500 - 700cc (Replaced Phase 1)
3. Replacement
  1. First 8 hours
    1. Total: 1400 + (75 cc/hour for 8 hours)
    2. Hourly: 250 cc/hour for 8 hours (2 Liters over 8h)
  2. Next 16 hours
    1. Total: 1400 + (75 cc/hour for 16 hours)
    2. Hourly: 163 cc/hour for 16 hours (2.6L over 16h)
Calculate Sodium Deficit and Sodium Requirement
1. Calculate Deficit
  1. Formula: 0.6 x (weight kg) x (135 - Serum Sodium)
  2. Example: (0.6 x 35 kilograms) x (135-120) = 315 meq
2. Add Maintenance
  1. Formula: 3 meq/kg/day x (weight kg)
  2. Example: 35 kg x 3 meq = 105 meq Sodium/24 hours
3. Subtract Replacement given Phase 1
  1. Phase 1 Fluid bolus
    1. Formula: 1000 cc contains 150 meq Sodium
    2. Example: 700 cc contains 105 meq Sodium
  2. Remaining Sodium Required: 315 - 105 = 210 meq
Choose Appropriate solution to replace sodium deficit
1. Available solutions
  1. 1/4 Normal Saline contains 38 meq/L Sodium
  2. 1/3 Normal Saline contains 51 meq/L Sodium
  3. 1/2 Normal Saline contains 77 meq/L Sodium
  4. Normal Saline contains 154 meq/L Sodium
2. Example
  1. First 8 hours: Replace half sodium deficit
    1. Sodium 157 meq in 2 Liters (78 meq/L)
    2. Fluid: 1/2 Normal Saline (77 meq/L)
  2. Next 16 hours: Replace half sodium deficit
    1. Sodium 157 meq in 2.6 Liters (60 meq/L)
    2. Fluid: 1/2 Normal Saline (77 meq/L)
Example Summary: 35 kg Child with hypotonic dehydration
1. First 8 hours: D5 1/2NS with 20 KCl at 250 cc/hours
2. Next 16 hours: D5 1/2NS with 20 KCl at 163 cc/hours
Monitoring
1. Monitor Serum Sodium every 2-4 hours
2. Raise Serum Sodium <= 2 meq/L/hours
Special Circumstance: Hyponatremic Seizure
1. Background
  1. Serum Sodium raised 5 meq/L with 6 ml/kg of 3% NaCl
2. Protocol
  1. Give 3% NaCl (0.5 meq NaCl/ml) IV over 1 hour
  2. Give 3% NaCl at 6 ml/kg/hour until Seizure stops

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This page was written by Scott Moses, MD. This page was last revised before 5/10/08, prior to consistent tracking of revision date. This page was last published on 6/1/2008. Please send comments and questions to the editor. Contact information may be found on the page About the Family Practice Notebook. These pages are best viewed with Microsoft Internet Explorer 6.0.