Maintenance Fluids Calculator

Pediatric maintenance intravenous fluids (MIVF) are traditionally calculated using the classic Holliday-Segar method, which estimates metabolic water requirements based on body weight. The standard tiering system divides weight into three distinct brackets: 100 mL/kg for the first 10 kg, 50 mL/kg for the next 10 kg (weights between 10 and 20 kg), and 20 mL/kg for every kilogram thereafter. To find the hourly rate, the total 24-hour volume is divided by 24. For acute resuscitation or shock management, an initial fluid bolus is calculated as 20 mL/kg of isotonic crystalloid, typically capped at a maximum of 1,000 mL per single administration to prevent volume overload.

Let us walk through the math for a pediatric patient weighing 15 kg who requires maintenance intravenous fluids. First, we calculate the daily fluid volume using the Holliday-Segar tiered formula. For the first 10 kg, the volume is 10 kg times 100 mL/kg, which equals 1,000 mL. For the remaining 5 kg (the weight between 10 kg and 15 kg), the volume is 5 kg times 50 mL/kg, which equals 250 mL. Adding these together gives a total daily maintenance requirement of 1,250 mL per 24 hours. To find the hourly infusion rate, divide 1,250 mL by 24 hours, resulting in approximately 52.1 mL/hour. If this patient also required an emergency fluid bolus for dehydration or hypovolemia, the 20 mL/kg rule applies: 15 kg multiplied by 20 mL/kg equals a 300 mL bolus.

Always reassess pediatric fluid requirements frequently, as clinical conditions such as fever, hyperventilation, or trauma can significantly alter metabolic water needs. Be cautious with hypotonic maintenance solutions in acute settings, as they carry an increased risk of hyponatremia; isotonic solutions are frequently favored in modern pediatric protocols. Finally, always cross-reference calculated maintenance rates against ongoing clinical losses, urine output, and serum electrolyte panels to ensure optimal patient safety.