Pediatric IV Rate & Maintenance Fluid Calculator
1. Maintenance Fluid Requirements (Holliday-Segar)
2. IV Drip Rate (Drops Per Minute)
Understanding Pediatric IV Calculations
In pediatric medicine, fluid management is critical because children have higher metabolic rates and different body water compositions than adults. Calculating the correct Intravenous (IV) rate involves two primary steps: determining the maintenance fluid requirement based on weight and then converting that into a flow rate or drip rate.
The Holliday-Segar Method (4-2-1 Rule)
The standard for calculating maintenance fluids in children is the Holliday-Segar Method. This method estimates the daily fluid needs based on metabolic demand:
- First 10 kg: 100 mL/kg/day (or 4 mL/kg/hr)
- Second 10 kg (11-20 kg): 50 mL/kg/day (or 2 mL/kg/hr)
- Each kg over 20 kg: 20 mL/kg/day (or 1 mL/kg/hr)
For example, a child weighing 15 kg would need: (10 kg × 4 mL) + (5 kg × 2 mL) = 40 + 10 = 50 mL/hr.
The IV Drip Rate Formula
If you are not using an electronic infusion pump and need to set a manual drip, you must calculate Drops Per Minute (gtt/min). The formula used is:
(Total Volume in mL × Drop Factor) ÷ Time in Minutes = Drip Rate (gtt/min)
In pediatric settings, a Microdrip set (60 gtt/mL) is almost always used because it allows for more precise control. Interestingly, when using a 60 gtt/mL set, the number of drops per minute is equal to the number of mL per hour.
Key Safety Considerations
Pediatric patients are at high risk for fluid overload or dehydration. When administering IV fluids:
- Double-check weight: Always use the most recent, accurate weight in kilograms.
- Consider Bolus: Maintenance calculations do not include "bolus" volumes needed for acute resuscitation.
- Monitor Output: Ensure urine output is monitored (target usually 1-2 mL/kg/hr).
Example Calculation
Scenario: A 12 kg child requires maintenance fluids using a 60 gtt/mL microdrip set.
- Maintenance: (10kg × 4) + (2kg × 2) = 44 mL/hr.
- Drip Rate: (44 mL × 60 gtt) / 60 mins = 44 gtt/min.