Heparin is a critical anticoagulant medication that requires precise dosing. Because it is high-alert medication, healthcare professionals must calculate the intravenous (IV) infusion rate (mL/hr) based on the concentration of the bag and the ordered dosage protocol.
The Core Formula
To determine the drip rate, you first need to know the concentration of the solution. The formula used by this calculator is:
Concentration: Total Units in Bag ÷ Bag Volume (mL) = Units/mL
In many clinical settings, heparin is dosed based on the patient's weight (Units/kg/hr). In this scenario, the total units required per hour must be calculated first:
Total Units/hr = (Ordered Units/kg/hr) × (Patient weight in kg)
Practical Example
Scenario: An order for 18 Units/kg/hr. The patient weighs 80kg. The heparin bag contains 25,000 Units in 250mL.
Step 1 (Concentration): 25,000 Units ÷ 250 mL = 100 Units/mL.
Step 2 (Dose in Units/hr): 18 Units × 80 kg = 1,440 Units/hr.
This calculator is intended for educational purposes and as a double-check tool for healthcare professionals. Clinical decisions should always be based on hospital protocols, physician orders, and independent verification. Always perform a manual calculation before starting an infusion.
function toggleWeightInput() {
var mode = document.getElementById("dosingMode").value;
var weightDiv = document.getElementById("weightContainer");
var doseLabel = document.getElementById("doseLabel");
if (mode === "weightBased") {
weightDiv.style.display = "block";
doseLabel.innerText = "Desired Dose (Units/kg/hr):";
} else {
weightDiv.style.display = "none";
doseLabel.innerText = "Desired Dose (Units/hr):";
}
}
function calculateHeparinRate() {
var mode = document.getElementById("dosingMode").value;
var weight = parseFloat(document.getElementById("patientWeight").value);
var totalUnits = parseFloat(document.getElementById("totalUnits").value);
var bagVolume = parseFloat(document.getElementById("bagVolume").value);
var desiredDoseInput = parseFloat(document.getElementById("desiredDose").value);
// Validation
if (isNaN(totalUnits) || isNaN(bagVolume) || isNaN(desiredDoseInput) || totalUnits <= 0 || bagVolume <= 0 || desiredDoseInput <= 0) {
alert("Please enter valid positive numbers for all fields.");
return;
}
if (mode === "weightBased" && (isNaN(weight) || weight <= 0)) {
alert("Please enter a valid patient weight.");
return;
}
// Calculation Logic
var concentration = totalUnits / bagVolume;
var actualDosePerHour;
var weightNoteText = "";
if (mode === "weightBased") {
actualDosePerHour = desiredDoseInput * weight;
weightNoteText = "Total dose: " + actualDosePerHour.toFixed(0) + " Units/hr based on " + weight + " kg.";
} else {
actualDosePerHour = desiredDoseInput;
weightNoteText = "Standard protocol dosing applied.";
}
var infusionRate = actualDosePerHour / concentration;
// Display Results
document.getElementById("resConcentration").innerText = concentration.toLocaleString(undefined, {minimumFractionDigits: 0, maximumFractionDigits: 2});
document.getElementById("resRate").innerText = infusionRate.toLocaleString(undefined, {minimumFractionDigits: 1, maximumFractionDigits: 2});
document.getElementById("weightNote").innerText = weightNoteText;
document.getElementById("resultsArea").style.display = "block";
// Smooth scroll to results
document.getElementById("resultsArea").scrollIntoView({ behavior: 'smooth', block: 'nearest' });
}