body {
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
line-height: 1.6;
color: #333;
max-width: 1200px;
margin: 0 auto;
padding: 20px;
background-color: #f9f9f9;
}
.calculator-container {
background: #ffffff;
padding: 30px;
border-radius: 12px;
box-shadow: 0 4px 15px rgba(0,0,0,0.1);
margin-bottom: 40px;
border: 1px solid #e1e1e1;
}
.calculator-title {
text-align: center;
color: #2c3e50;
margin-bottom: 25px;
font-size: 24px;
font-weight: 700;
border-bottom: 2px solid #3498db;
padding-bottom: 10px;
display: inline-block;
}
.input-grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 20px;
margin-bottom: 25px;
}
.input-group {
margin-bottom: 15px;
}
.input-group label {
display: block;
margin-bottom: 8px;
font-weight: 600;
color: #555;
}
.input-group input, .input-group select {
width: 100%;
padding: 12px;
border: 1px solid #ccc;
border-radius: 6px;
font-size: 16px;
transition: border-color 0.3s;
box-sizing: border-box;
}
.input-group input:focus {
border-color: #3498db;
outline: none;
}
.calc-btn {
width: 100%;
background-color: #3498db;
color: white;
border: none;
padding: 15px;
font-size: 18px;
font-weight: bold;
border-radius: 6px;
cursor: pointer;
transition: background-color 0.2s;
}
.calc-btn:hover {
background-color: #2980b9;
}
.result-section {
margin-top: 30px;
background-color: #f0f7fb;
padding: 20px;
border-radius: 8px;
border-left: 5px solid #3498db;
display: none;
}
.result-row {
display: flex;
justify-content: space-between;
margin-bottom: 10px;
padding-bottom: 10px;
border-bottom: 1px solid #dcebf5;
}
.result-row:last-child {
border-bottom: none;
margin-bottom: 0;
padding-bottom: 0;
}
.result-label {
font-weight: 600;
color: #444;
}
.result-value {
font-weight: 800;
color: #2c3e50;
font-size: 18px;
}
.error-msg {
color: #e74c3c;
text-align: center;
margin-top: 10px;
font-weight: bold;
display: none;
}
.article-content {
background: #fff;
padding: 30px;
border-radius: 12px;
box-shadow: 0 2px 10px rgba(0,0,0,0.05);
}
.article-content h2 {
color: #2c3e50;
margin-top: 30px;
border-bottom: 1px solid #eee;
padding-bottom: 10px;
}
.article-content h3 {
color: #3498db;
margin-top: 25px;
}
.article-content ul {
margin-left: 20px;
}
.formula-box {
background-color: #f8f9fa;
padding: 15px;
border-radius: 6px;
font-family: monospace;
margin: 15px 0;
border: 1px solid #e1e1e1;
}
@media (max-width: 768px) {
.input-grid {
grid-template-columns: 1fr;
}
}
Understanding the Dose Rate Calculation Formula
In critical care medicine, nursing, and pharmacy, calculating the correct IV drip rate is vital for patient safety. The dose rate calculation determines the speed at which an intravenous fluid containing a specific medication should be administered to achieve a prescribed therapeutic effect. This calculator focuses on the "weight-based" infusion rate, commonly measured in milliliters per hour (mL/hr), derived from a prescription in micrograms per kilogram per minute (mcg/kg/min).
The Core Formulas
To manually calculate the infusion rate, you need to follow a multi-step process involving conversion of units and volume. The mathematical logic used in this calculator is based on the following standard nursing formulas:
1. Determine Concentration:
Concentration (mcg/mL) = (Total Drug in mg × 1000) / Total Volume in mL
2. Determine Total Dose Required per Hour:
Hourly Dose (mcg/hr) = Ordered Dose (mcg/kg/min) × Weight (kg) × 60 min
3. Calculate Flow Rate:
Flow Rate (mL/hr) = Hourly Dose (mcg/hr) / Concentration (mcg/mL)
Step-by-Step Calculation Example
Let's look at a realistic scenario often found in ICUs using the inputs typically required for Dopamine or Norepinephrine infusions:
- Drug on Hand: 400 mg of medication diluted in 250 mL of D5W or Saline.
- Patient Weight: 80 kg.
- Prescribed Dose: 5 mcg/kg/min.
Step 1: Calculate Concentration
First, convert milligrams to micrograms and divide by volume:
400 mg = 400,000 mcg.
400,000 mcg / 250 mL = 1,600 mcg/mL.
Step 2: Calculate Hourly Dose Requirement
Multiply the dose by the patient's weight and the minutes in an hour:
5 mcg × 80 kg = 400 mcg/min.
400 mcg/min × 60 mins = 24,000 mcg/hr.
Step 3: Solve for Flow Rate (mL/hr)
Divide the hourly requirement by the concentration:
24,000 mcg/hr / 1,600 mcg/mL = 15 mL/hr.
Therefore, to deliver 5 mcg/kg/min to an 80kg patient with this concentration, you must set the IV pump to 15 mL/hr.
Why Accuracy Matters
Medications delivered via continuous infusion (such as vasoactive drugs, sedatives, or anti-arrhythmics) have narrow therapeutic indices. Small errors in the calculation formula can lead to significant underdosing (ineffective treatment) or overdosing (toxicity). While automated smart pumps are common, understanding the manual dose rate calculation formula is a mandatory skill for medical professionals to double-check pump settings and ensure patient safety during equipment failure.
function calculateFlowRate() {
// Get Input Values
var drugMg = document.getElementById('drugAmount').value;
var volumeMl = document.getElementById('volume').value;
var weightKg = document.getElementById('weight').value;
var doseMcgKgMin = document.getElementById('dose').value;
// Get Elements for display
var resultSection = document.getElementById('resultSection');
var errorMsg = document.getElementById('errorMsg');
var concentrationDisplay = document.getElementById('concentrationResult');
var doseDisplay = document.getElementById('dosePerHourResult');
var rateDisplay = document.getElementById('flowRateResult');
// Validation: Check for empty or non-positive numbers
if (drugMg === "" || volumeMl === "" || weightKg === "" || doseMcgKgMin === "" ||
parseFloat(drugMg) <= 0 || parseFloat(volumeMl) <= 0 || parseFloat(weightKg) <= 0 || parseFloat(doseMcgKgMin) 1000) {
doseDisplay.innerHTML = (dosePerHour/1000).toFixed(2) + " mg/hr";
} else {
doseDisplay.innerHTML = dosePerHour.toFixed(0) + " mcg/hr";
}
rateDisplay.innerHTML = flowRate.toFixed(1) + " mL/hr";
// Show Result Section
resultSection.style.display = "block";
}