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Required Flow Rate
0 mL/hr
Guide to Nitroglycerin IV Calculations
Nitroglycerin (NTG) is a potent vasodilator commonly used in critical care settings for managing conditions such as angina pectoris, myocardial infarction, and severe hypertension. Because of its potency, accurate calculation of the infusion rate is vital for patient safety. This calculator helps nursing and medical professionals convert ordered doses into pump settings (flow rates).
Common Dosing Strategies
Nitroglycerin can be administered using two primary dosing methods:
Standard Dosing (mcg/min): This is the most common method. The physician orders a specific amount of micrograms to be delivered per minute (e.g., "Start NTG at 5 mcg/min"). The patient's weight does not affect the calculation.
Weight-Based Dosing (mcg/kg/min): Used less frequently for NTG but common in pediatrics or specific protocols. The dose is calculated based on the patient's body weight in kilograms.
Calculation Formulas
To determine the infusion pump setting in milliliters per hour (mL/hr), the calculator uses the following logic:
1. Determine Concentration
First, calculate the concentration of the drug in the IV bag:
Concentration (mcg/mL) = [Total Drug (mg) × 1000] / Total Volume (mL)
Medical Disclaimer: This calculator is intended for educational and verification purposes only. It should not replace professional clinical judgment or institutional protocols. Always double-check calculations and pump settings before administering medication to a patient.
function toggleWeightInput() {
var doseType = document.getElementById("dosingUnit").value;
var weightDiv = document.getElementById("weightContainer");
var doseLabel = document.getElementById("doseUnitLabel");
if (doseType === "mcg_kg_min") {
weightDiv.style.display = "block";
doseLabel.innerText = "mcg/kg/min";
} else {
weightDiv.style.display = "none";
doseLabel.innerText = "mcg/min";
}
}
function calculateNitroglycerinRate() {
// Clear previous results and errors
document.getElementById("resultBox").style.display = "none";
document.getElementById("errorDisplay").style.display = "none";
// Get Input Values
var mg = parseFloat(document.getElementById("drugAmount").value);
var vol = parseFloat(document.getElementById("totalVolume").value);
var dose = parseFloat(document.getElementById("orderedDose").value);
var doseType = document.getElementById("dosingUnit").value;
var weight = 0;
// Validation
if (isNaN(mg) || mg <= 0 || isNaN(vol) || vol <= 0 || isNaN(dose) || dose < 0) {
document.getElementById("errorDisplay").style.display = "block";
return;
}
// Calculate Concentration
// 1 mg = 1000 mcg
var totalMcg = mg * 1000;
var concentrationMcgPerMl = totalMcg / vol;
// Display Concentration Preview (Optional helpful UI)
document.getElementById("concentrationDisplay").innerText =
"Concentration: " + concentrationMcgPerMl.toFixed(2) + " mcg/mL (" + mg + " mg / " + vol + " mL)";
var flowRate = 0;
if (doseType === "mcg_kg_min") {
weight = parseFloat(document.getElementById("patientWeight").value);
if (isNaN(weight) || weight <= 0) {
document.getElementById("errorDisplay").style.display = "block";
document.getElementById("errorDisplay").innerText = "Please enter a valid patient weight.";
return;
}
// Formula: (Dose * Weight * 60) / Concentration
flowRate = (dose * weight * 60) / concentrationMcgPerMl;
} else {
// Formula: (Dose * 60) / Concentration
flowRate = (dose * 60) / concentrationMcgPerMl;
}
// Check for infinite or NaN results
if (!isFinite(flowRate) || isNaN(flowRate)) {
document.getElementById("errorDisplay").style.display = "block";
document.getElementById("errorDisplay").innerText = "Calculation Error. Check inputs.";
return;
}
// Display Result
document.getElementById("resultBox").style.display = "block";
document.getElementById("finalRate").innerText = flowRate.toFixed(1) + " mL/hr";
document.getElementById("concentrationResult").innerText =
"Based on concentration: " + concentrationMcgPerMl.toFixed(1) + " mcg/mL";
}