Please enter valid positive numbers for all fields.
IV Pump Setting
0.0 mL/hr
Concentration:– mcg/mL
function calculateIVRate() {
// 1. Get input values
var dose = document.getElementById('orderedDose').value;
var weight = document.getElementById('patientWeight').value;
var drugMg = document.getElementById('drugAmount').value;
var volume = document.getElementById('totalVolume').value;
var errorDiv = document.getElementById('errorDisplay');
var resultDiv = document.getElementById('resultDisplay');
// 2. Validate inputs
if (dose === "" || weight === "" || drugMg === "" || volume === "" ||
isNaN(dose) || isNaN(weight) || isNaN(drugMg) || isNaN(volume)) {
errorDiv.style.display = "block";
resultDiv.style.display = "none";
return;
}
var doseNum = parseFloat(dose);
var weightNum = parseFloat(weight);
var drugMgNum = parseFloat(drugMg);
var volumeNum = parseFloat(volume);
if (doseNum <= 0 || weightNum <= 0 || drugMgNum <= 0 || volumeNum <= 0) {
errorDiv.innerText = "Values must be greater than zero.";
errorDiv.style.display = "block";
resultDiv.style.display = "none";
return;
}
// 3. Perform Calculations
// Step A: Convert total drug amount from mg to mcg
var totalDrugMcg = drugMgNum * 1000;
// Step B: Calculate Concentration (mcg/mL)
var concentration = totalDrugMcg / volumeNum;
// Step C: Calculate Total Dose Required Per Minute (mcg/min)
var dosePerMinute = doseNum * weightNum;
// Step D: Calculate Total Dose Required Per Hour (mcg/hr)
var dosePerHour = dosePerMinute * 60;
// Step E: Calculate Flow Rate (mL/hr) = Dose per hour / Concentration
var flowRate = dosePerHour / concentration;
// 4. Update UI
errorDiv.style.display = "none";
resultDiv.style.display = "block";
document.getElementById('finalRate').innerText = flowRate.toFixed(1) + " mL/hr";
document.getElementById('concentrationResult').innerText = concentration.toFixed(1);
}
Understanding the Infusion Rate Formula: mcg/kg/min to mL/hr
In critical care settings, vasoactive medications (such as Dopamine, Dobutamine, or Norepinephrine) are frequently prescribed based on patient weight. The order usually appears as micrograms per kilogram per minute (mcg/kg/min). However, IV infusion pumps are typically programmed in milliliters per hour (mL/hr). This calculator bridges that gap, ensuring accurate medication delivery.
The Conversion Formula
To convert a weight-based dose into an infusion pump rate, you must account for the patient's weight, the desired dose, and the concentration of the medication in the IV bag.
If you prefer to calculate this manually, follow these four steps:
Convert Drug Mass: Most drug vials are labeled in milligrams (mg). Convert this to micrograms (mcg) by multiplying by 1,000. Formula: mg × 1000 = mcg
Calculate Concentration: Determine how many micrograms of drug are in every milliliter of fluid. Formula: Total mcg ÷ Total Volume (mL) = Concentration (mcg/mL)
Calculate Hourly Dose: Determine the total medication needed for the patient for one hour. Formula: Dose (mcg/kg/min) × Weight (kg) × 60 = Dose/hr (mcg/hr)
Solve for Rate: Divide the hourly dose by the concentration. Formula: Dose/hr ÷ Concentration = Rate (mL/hr)
Practical Clinical Example
Let's look at a common scenario in an ICU setting involving Dopamine.
Parameter
Value
Physician Order
5 mcg/kg/min
Patient Weight
80 kg
Pharmacy Prep
400 mg Dopamine in 250 mL D5W
Step 1 (Concentration): Convert 400 mg to 400,000 mcg. Divide by 250 mL. 400,000 mcg / 250 mL = 1,600 mcg/mL
Step 2 (Hourly Load): Calculate the needs per minute, then per hour. 5 mcg × 80 kg = 400 mcg/min 400 mcg/min × 60 min = 24,000 mcg/hr
Dopamine: Often used for hemodynamic support in shock.
Dobutamine: Used for heart failure and cardiogenic shock.
Norepinephrine (Levophed): A vasopressor used to raise blood pressure.
Epinephrine: Used for anaphylaxis or cardiac arrest/shock scenarios.
Nitroprusside: Used for rapid reduction of blood pressure (hypertensive crisis).
Frequently Asked Questions
Why do we multiply by 60 in the formula?
The order is typically given in minutes (mcg/kg/min), but IV pumps are programmed in hours (mL/hr). Multiplying by 60 converts the per-minute dose into a per-hour requirement.
What if my drug amount is already in micrograms (mcg)?
If your pharmacy provides the drug amount in micrograms, you do not need to multiply by 1,000. Simply divide the total mcg by the volume (mL) to get your concentration.
Does this formula work for pediatric patients?
Yes, the math remains the same. However, pediatric infusions often use much smaller volumes and specialized concentrations ("Rule of 6"). Always double-check calculations and pump limits for pediatric patients.