The most common problem requiring fluid therapy in pediatrics is hypovolemia or dehydration related to vomiting and diarrhea from gastroenteritis. Severe hypovolemia is defined as volume depletion ≥10 percent and this can lead to ischemic end-organ damage, shock and death can occur
Signs of severe hypovolemia: capillary refill > three seconds, cool and mottled extremities, lethargy, hypotension
Fluid therapy can be divided into 2 phases: 1) Repletion therapy and 2) maintenance therapy.
1) Repletion therapy replaces any current water and electrolyte deficits, replaces any ongoing abnormal losses, and returns the patient to a normal volume and electrolyte status.
Repletion therapy:
Emergent intravenous fluid (IV) therapy should begin with rapid infusion of 20 mL/kg of isotonic saline.
Reassessment of the child is needed and similar isotonic fluid infusions should be repeated as needed until adequate perfusion is restored. If IV access is not readily obtainable, intraosseous rehydration is an effective alternative
For Moderate hypovolemia, a bolus of 10 mL/kg is given over 30 to 60 minutes. Reassessment of the child will be needed to decide on administration of a repeat intravenous bolus versus transition to oral therapy.
Type of fluid:Isotonic crystalloid/Isotonic saline (0.9 percent saline solution or normal saline) is the isotonic solution of choice to restore the circulatory volume.
Warning: Rapid administration of hypotonic or hypertonic crystalloid solutions for emergent volume expansion is never recommended in pediatric patients: can result in serious complications, including dysnatremias, cerebral edema, and cerebral demyelination.
2) Maintenance therapy replaces the expected ongoing losses of water and electrolytes from normal physiologic processes. The commonly used method for approximating water loss (and therefore the water requirement) is the Holliday-Segar nomogram as follows:
Calculator: Maintenance fluid calculation for children based on daily fluid requirements
Fluid_infusion_rate = Daily_volume / 24
- For infants 3.5 to 10 kg, the daily fluid requirement is 100 mL/kg.(10 ml x 100 ml/24)-42 ml/hr
- For children 11 to 20 kg, the daily fluid requirement is 1000 mL + 50 mL/kg for every kg over 10.( so if 15 kg, it would be 1250 ml/24)—52 ml/hr
- For children >20 kg, the daily fluid requirement is 1500 mL + 20 mL/kg for every kg over 20, up to a maximum of 2400 mL daily.
- This calculation does not apply to newborn infants (ie, from 0 to 28 days after full-term delivery).
- To determine the composition of maintenance fluids, refer to UpToDate topics on intravenous fluid therapy in children.
Calculator: Maintenance fluid calculation for children based on hourly fluid requirements
Fluid infusion rate= Fluid requirement x weight(kg)
- Fluid infusion rate is determined as follows:
- Weight between 3.5 and 10 kg, hourly fluid requirement is 4 mL/kg per hour.
- (ex: 10 kg would be 40 ml/hr.)
- Weight >10 kg to 20 kg, hourly fluid requirement is 40 mL/hour for first 10 kg of body weight plus 2 mL/kg per hour for any increment of weight over 10 kg.
- (ex: 15 kg would be 40 ml/hr + 10ml/hr) so 50 kg x 50 ml/hr= 750 ml/hr
- Weight >20 kg, hourly fluid requirement is 60 mL/hour for first 20 kg of body weight plus 1 mL/kg per hour for any increment of weight over 20 kg, to a maximum of 100 mL/hour (up to a maximum of 2400 mL daily).
- This calculation does not apply to newborn infants (ie, from 0 to 28 days after full-term delivery).
- To determine the composition of maintenance fluids, refer to UpToDate topics on intravenous fluid therapy in children.
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