Pediatric Maintenance Fluid Calculation

Because infants and young children suffer the ill effects of dehydration or fluid overload much more quickly than adults, it is important for the nurse to check the accuracy of all fluid orders with the same care used to check the safety of drug dosage orders. The following formula is widely used to calculate usual maintenance fluid requirements for children. Maintenance fluid is the amount needed to maintain adequate hydration in a healthy child. More fluid is given to compensate for certain pathologic states, and less fluid may be needed if pathology indicates that fluid should be restricted.

Steps

1. Convert the child’s weight in pounds to kilograms by multiplying the number of pounds by 0.45.
2. Calculate 100 mL of fluid per kilogram per 24 hours for the 1st 10 kg of the child’s body weight.
3. Calculate 50 mL of fluid per kilogram per 24 hours for the 2nd 10 kg of the child’s body weight.
4. Calculate 10 to 25 mL of fluid per kilogram per 24 hours for each kilogram of body weight over 20.
5. Add the products of steps 2, 3, and 4 to determine the milliliters of fluid needed per 24 hours.
6. To calculate the IV rate, divide the sum derived in step 5 by 24 (number of hours in a day). Milliliters per hour will be the same as microdrops per minute.

NOTE: Add 12% maintenance fluid (to the sum of step 5) for every degree (Celsius) of body temp over 37.5°C. Eliminate any step not applicable to the weight of the child.

Examples of Maintenance Fluid Calculation for Children

Calculation to Determine the Maintenance Fluid for a 15-lb Infant

• Convert 15 lb to kilograms by multiplying 15 × 0.45 = 6.75 kg.
• Allow 100 mL/kg for the 6.75 kg ( = 675 mL).
• Divide 675 by 24 to determine the rate of IV if indicated.
• RATE = 28 mL/h or 28 gtt/min (microdrop).

Calculation to Determine the Maintenance Fluid for a 40-lb Child

• Convert 40 lb to kilograms by multiplying 40 ×0.45 = 18 kg.
• Allow 100 mL/kg for the 1st 10 kg ( = 1000 mL).
• Allow 50 mL/kg for the remaining 8 kg ( = 400 mL).
• Add the 1000 mL to the 400 mL ( = 1400 mL).
• Divide the total of 1400 by 24 to determine the rate.
• rate = 58 mL/h or 58 gtt/min (microdrop).

Calculation to Determine the Maintenance Fluid for a 70-lb Child

• Convert 70 lb to kilograms by multiplying 70 ×0.45 = 31.5 kg.
• Allow 100 mL/kg for the 1st 10 kg ( = 1000 mL).
• Allow 50 mL/kg for the 2nd 10 kg ( = 500 mL).
• Allow 20 mL/kg for the remaining 11.5 kg ( = 230 mL). (Physician preference and age and condition of child will determine whether more than 10 mL/kg is given for each kilogram over 20.)
• Add 1000 mL+ 500 mL+ 230 mL ( = 1730 mL).
• Divide 1730 by 24 to determine the rate.
• rate = 72 mL/h or 72 gtt/min (microdrop).