Venturi Mask Flow Rate Calculator

by
Venturi Mask Flow Rate Calculator .venturi-calculator-wrapper { max-width: 800px; margin: 0 auto; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif; color: #333; line-height: 1.6; } .venturi-calc-box { background: #f8f9fa; border: 1px solid #e9ecef; border-radius: 8px; padding: 30px; margin-bottom: 40px; box-shadow: 0 4px 6px rgba(0,0,0,0.05); } .venturi-calc-title { text-align: center; margin-bottom: 25px; color: #2c3e50; font-size: 24px; font-weight: 700; } .venturi-input-group { margin-bottom: 20px; } .venturi-input-group label { display: block; margin-bottom: 8px; font-weight: 600; color: #495057; } .venturi-input-group input { width: 100%; padding: 12px; border: 1px solid #ced4da; border-radius: 4px; font-size: 16px; box-sizing: border-box; } .venturi-input-group input:focus { border-color: #007bff; outline: none; box-shadow: 0 0 0 3px rgba(0,123,255,0.25); } .venturi-btn { width: 100%; background-color: #007bff; color: white; border: none; padding: 14px; font-size: 18px; font-weight: 600; border-radius: 4px; cursor: pointer; transition: background-color 0.2s; } .venturi-btn:hover { background-color: #0056b3; } .venturi-result-box { margin-top: 25px; padding: 20px; background-color: #fff; border: 1px solid #dee2e6; border-radius: 4px; display: none; } .venturi-result-row { display: flex; justify-content: space-between; padding: 10px 0; border-bottom: 1px solid #eee; } .venturi-result-row:last-child { border-bottom: none; } .venturi-result-label { font-weight: 600; color: #6c757d; } .venturi-result-value { font-weight: 700; color: #2c3e50; font-size: 18px; } .venturi-result-highlight { color: #28a745; font-size: 20px; } .venturi-content h2 { color: #2c3e50; margin-top: 30px; border-bottom: 2px solid #007bff; padding-bottom: 10px; display: inline-block; } .venturi-content h3 { color: #495057; margin-top: 20px; } .venturi-content ul { margin-bottom: 20px; padding-left: 20px; } .venturi-content li { margin-bottom: 10px; } .error-msg { color: #dc3545; font-weight: 600; margin-top: 10px; display: none; } .ref-table { width: 100%; border-collapse: collapse; margin: 20px 0; } .ref-table th, .ref-table td { border: 1px solid #dee2e6; padding: 12px; text-align: left; } .ref-table th { background-color: #f1f3f5; font-weight: 600; }
Venturi Mask Flow Rate Calculator
Enter percentage between 22% and 100%.
The flow rate set on the oxygen source (Liters Per Minute).
Calculated Air:O2 Ratio: –
Entrainment Factor (Total Parts): –
Total Flow to Patient: –
*Calculation assumes room air is 21% Oxygen.

Understanding Venturi Mask Flow Calculations

This calculator determines the Total Flow delivered to a patient when using an Air-Entrainment Mask (AEM), commonly known as a Venturi mask. Unlike standard nasal cannulas, Venturi masks are high-flow devices designed to deliver a precise Fraction of Inspired Oxygen (FiO2) regardless of the patient's respiratory pattern.

To ensure the patient receives the exact prescribed oxygen concentration, the total flow delivered by the mask must exceed the patient's peak inspiratory flow demand (typically 40-60 LPM during respiratory distress).

The Magic Box Formula

To calculate the total flow, we first determine the Air-to-Oxygen entrainment ratio using the standard formula:

Liters of Air = (100 – FiO2) / (FiO2 – 21)

Note: While some clinical shortcuts use 20 for room air, this calculator uses 21 for greater mathematical precision.

How to Calculate Total Flow

  1. Calculate the Ratio: Determine how many parts of air are entrained for every 1 part of oxygen.
  2. Sum the Parts: Add the air parts and the oxygen part (1) together to get the Total Parts.
  3. Multiply by Flow: Multiply the Total Parts by the Oxygen Flowmeter setting (LPM).

Example Calculation

If a patient requires 40% FiO2 and the flowmeter is set to 8 LPM:

  • Step 1 (Ratio): (100 – 40) / (40 – 21) = 60 / 19 ≈ 3.16 parts air to 1 part O2.
  • Step 2 (Total Parts): 3.16 (Air) + 1 (O2) = 4.16.
  • Step 3 (Total Flow): 8 LPM (Input) × 4.16 = 33.3 LPM Total Flow.

Standard Air Entrainment Ratios

Below are common Venturi mask settings and their approximate entrainment ratios:

FiO2 (%) Air : O2 Ratio Total Parts
24% 25 : 1 26
28% 10 : 1 11
31% 7 : 1 8
35% 5 : 1 6
40% 3 : 1 4
50% 1.7 : 1 2.7
60% 1 : 1 2

Why is Total Flow Important?

If the Total Flow calculated is less than the patient's inspiratory demand, the patient will draw in room air around the mask ports during inspiration. This dilutes the oxygen concentration, meaning the patient receives a lower FiO2 than intended. To correct this, the Respiratory Therapist must increase the oxygen flow rate on the flowmeter, which proportionally increases the entrained air and total flow while maintaining the same FiO2.

function calculateTotalFlow() { // 1. Get Elements var fio2Input = document.getElementById('fio2Input'); var o2FlowInput = document.getElementById('o2FlowInput'); var resultBox = document.getElementById('resultDisplay'); var ratioResult = document.getElementById('ratioResult'); var partsResult = document.getElementById('partsResult'); var totalFlowResult = document.getElementById('totalFlowResult'); var errorMsg = document.getElementById('errorMsg'); // 2. Parse Values var fio2 = parseFloat(fio2Input.value); var o2Flow = parseFloat(o2FlowInput.value); // 3. Reset State errorMsg.style.display = 'none'; resultBox.style.display = 'none'; // 4. Validation if (isNaN(fio2) || isNaN(o2Flow)) { errorMsg.innerText = "Please enter valid numbers for both fields."; errorMsg.style.display = 'block'; return; } if (fio2 = 100) { errorMsg.innerText = "FiO2 must be greater than 21% and less than 100%."; errorMsg.style.display = 'block'; return; } if (o2Flow <= 0) { errorMsg.innerText = "Oxygen flow rate must be greater than 0."; errorMsg.style.display = 'block'; return; } // 5. Calculation Logic // Formula: Air/O2 ratio = (100 – FiO2) / (FiO2 – 21) var numerator = 100 – fio2; var denominator = fio2 – 21; // Calculate Ratio (Air parts per 1 part O2) var airParts = numerator / denominator; // Total Parts = Air Parts + 1 (Oxygen Part) var totalParts = airParts + 1; // Total Flow = Oxygen Flow * Total Parts var totalFlow = o2Flow * totalParts; // 6. Formatting Results // Round ratio to 1 decimal place for readability var ratioDisplay = airParts.toFixed(1) + " : 1"; // Round total parts to 2 decimal places var partsDisplay = totalParts.toFixed(2); // Round total flow to 1 decimal place var flowDisplay = totalFlow.toFixed(1) + " LPM"; // 7. Update DOM ratioResult.innerText = ratioDisplay; partsResult.innerText = partsDisplay; totalFlowResult.innerText = flowDisplay; // Show result box resultBox.style.display = 'block'; }

Leave a Comment