Use this to convert a prescribed dose (e.g., mcg/kg/min) into the pump setting (mL/hr).
Drug Concentration:0 mcg/mL
Required Pump Rate:0 mL/hr
function calculateStandardRate() {
var volume = parseFloat(document.getElementById("totalVolume").value);
var time = parseFloat(document.getElementById("infusionTime").value);
var dropFactor = parseFloat(document.getElementById("dropFactor").value);
var resultBox = document.getElementById("standardResult");
if (isNaN(volume) || isNaN(time) || time <= 0) {
alert("Please enter a valid Volume and Time (Time must be greater than 0).");
return;
}
// 1. Calculate mL/hr
var flowRate = volume / time;
// 2. Calculate gtt/min = (Volume * DropFactor) / (Time in minutes)
// Time is in hours, so multiply by 60
var dripRate = (volume * dropFactor) / (time * 60);
// Display results
resultBox.style.display = "block";
document.getElementById("resFlowRate").innerHTML = flowRate.toFixed(1) + " mL/hr";
document.getElementById("resDripRate").innerHTML = Math.round(dripRate) + " gtt/min";
}
function calculateDosageRate() {
var weight = parseFloat(document.getElementById("patientWeight").value);
var dose = parseFloat(document.getElementById("orderedDose").value); // mcg/kg/min
var drugMg = parseFloat(document.getElementById("drugAmount").value); // mg
var volume = parseFloat(document.getElementById("diluentVolume").value); // mL
var resultBox = document.getElementById("dosageResult");
if (isNaN(weight) || isNaN(dose) || isNaN(drugMg) || isNaN(volume) || volume <= 0) {
alert("Please enter all fields correctly. Volume must be greater than 0.");
return;
}
// 1. Convert Drug Amount to mcg (1 mg = 1000 mcg)
var drugMcg = drugMg * 1000;
// 2. Calculate Concentration (mcg/mL)
var concentration = drugMcg / volume;
// 3. Calculate Total Dose Required per Hour (mcg/hr)
// Dose is mcg/kg/min.
// Total Dose/min = Dose * Weight
// Total Dose/hr = Dose * Weight * 60
var dosePerHour = dose * weight * 60;
// 4. Calculate Rate (mL/hr) = DosePerHour / Concentration
var rate = dosePerHour / concentration;
// Display Results
resultBox.style.display = "block";
document.getElementById("resConcentration").innerHTML = concentration.toFixed(1) + " mcg/mL";
document.getElementById("resDosageRate").innerHTML = rate.toFixed(1) + " mL/hr";
}
How to Calculate Rate for Infusion Pump
Calculating the correct infusion pump rate is a critical skill for nurses, paramedics, and healthcare professionals. Ensuring precise medication delivery prevents under-dosing or toxicity. While modern smart pumps automate many of these features, understanding the manual formulas is essential for verifying settings and handling equipment failure.
1. The Basic Flow Rate Formula (mL/hr)
The most common setting on an electronic infusion pump is the flow rate, measured in milliliters per hour (mL/hr). This determines how quickly the fluid enters the patient's bloodstream.
The Formula:
Rate (mL/hr) = Total Volume (mL) ÷ Total Time (hours)
Example: If a doctor orders 1,000 mL of Normal Saline to infuse over 8 hours:
Calculation: 1,000 ÷ 8 = 125 mL/hr.
2. Calculating Drop Rate (gtt/min) for Gravity Infusion
When an electronic pump is not available, nurses use gravity tubing regulated by a roller clamp. The rate is calculated by counting drops per minute (gtt/min). To calculate this, you must know the Drop Factor of your tubing (found on the packaging).
Common Drop Factors:
Macro Drip: 10, 15, or 20 gtt/mL (used for general hydration and fast rates).
Micro Drip: 60 gtt/mL (used for pediatrics or precise medication).
The Formula:
Drops/min = (Total Volume (mL) × Drop Factor) ÷ Time (minutes)
Example: Infuse 100 mL over 30 minutes using a 15 gtt/mL set:
Calculation: (100 × 15) ÷ 30 = 1,500 ÷ 30 = 50 gtt/min.
3. Weight-Based Dosage Calculations
Critical care medications (such as Dopamine, Dobutamine, or Propofol) are often prescribed based on the patient's body weight (e.g., mcg/kg/min). To program the pump, you must convert this dosage into mL/hr.
The 4-Step Process:
Convert Drug Amount: Ensure drug mass is in the same unit as the dose (usually convert mg to mcg).
Calculate Concentration: Total Drug ÷ Total Volume = Concentration per mL.
Solve for Rate: Hourly Dose ÷ Concentration = mL/hr.
Example: A 70 kg patient needs 5 mcg/kg/min. You have 400 mg of drug in 250 mL.
Concentration: 400,000 mcg ÷ 250 mL = 1,600 mcg/mL.
Hourly Dose: 5 mcg × 70 kg × 60 min = 21,000 mcg/hr.
Pump Rate: 21,000 ÷ 1,600 = 13.1 mL/hr.
Safety Tips
Always double-check your math, especially for high-alert medications. If the calculated rate seems unusually high or low compared to standard protocols, verify the order and your calculation with a colleague or pharmacist before programming the infusion pump.