In pediatric medicine, fluid management is critical because children have a higher percentage of total body water and a higher metabolic rate than adults. Miscalculating drip rates can lead to fluid overload or dehydration much faster in infants and children.
The Holliday-Segar Method (4-2-1 Rule)
The standard way to determine maintenance fluid requirements in pediatrics is the 4-2-1 rule. This calculates the hourly rate based on the child's weight:
First 10 kg: 4 mL/kg/hr
Second 10 kg (11-20 kg): + 2 mL/kg/hr
Each kg over 20 kg: + 1 mL/kg/hr
The Drip Rate Formula
Once the total volume and time are known, the drip rate (drops per minute) is calculated using this formula:
(Total Volume in mL × Drop Factor) / (Time in Hours × 60) = Drops per Minute (gtt/min)
Realistic Example Calculation
Suppose you have a child weighing 15 kg. According to the 4-2-1 rule:
First 10 kg: 10 × 4 = 40 mL/hr
Remaining 5 kg: 5 × 2 = 10 mL/hr
Total Maintenance Rate: 50 mL/hr
If using a standard pediatric microdrip set (60 gtt/mL):
(50 mL × 60 gtt/mL) / 60 minutes = 50 gtt/min. Note: With a microdrip set (60 gtt/mL), the mL/hr rate is always equal to the gtt/min rate.
Pediatric Safety Precautions
Always verify calculations with a second clinician. Pediatric patients should ideally use an infusion pump for precision. If manual gravity infusion is used, microdrip sets (60 gtt/mL) are standard to minimize the risk of accidental bolus infusion.
function calculateMaintenanceFluid() {
var weight = parseFloat(document.getElementById('childWeight').value);
var hourlyRate = 0;
var resultDiv = document.getElementById('maintenanceResult');
if (isNaN(weight) || weight <= 0) {
resultDiv.innerHTML = "Please enter a valid weight.";
resultDiv.style.color = "#d9534f";
return;
}
if (weight <= 10) {
hourlyRate = weight * 4;
} else if (weight <= 20) {
hourlyRate = 40 + (weight – 10) * 2;
} else {
hourlyRate = 60 + (weight – 20) * 1;
}
var dailyRate = hourlyRate * 24;
resultDiv.style.color = "#0056b3";
resultDiv.innerHTML = "Maintenance Rate: " + hourlyRate.toFixed(1) + " mL/hr (Total Daily Volume: " + dailyRate.toFixed(0) + " mL/day)";
// Auto-fill the IV Volume and Time in the next section for convenience
document.getElementById('ivVolume').value = hourlyRate.toFixed(1);
document.getElementById('ivHours').value = 1;
}
function calculateDripRate() {
var vol = parseFloat(document.getElementById('ivVolume').value);
var hours = parseFloat(document.getElementById('ivHours').value);
var factor = parseFloat(document.getElementById('dropFactor').value);
var resultDiv = document.getElementById('dripResult');
if (isNaN(vol) || isNaN(hours) || vol <= 0 || hours <= 0) {
resultDiv.innerHTML = "Please enter valid volume and time.";
resultDiv.style.color = "#d9534f";
return;
}
var totalMinutes = hours * 60;
var dripRate = (vol * factor) / totalMinutes;
resultDiv.style.color = "#28a745";
resultDiv.innerHTML = "Infusion Rate: " + dripRate.toFixed(1) + " gtt/min";
}