How to Calculate Tidal Volume by Weight

:root {
–primary-color: #004a99;
–success-color: #28a745;
–background-color: #f8f9fa;
–text-color: #333;
–border-radius: 8px;
–shadow: 0 4px 12px rgba(0,0,0,0.1);
}
body {
font-family: ‘Segoe UI’, Tahoma, Geneva, Verdana, sans-serif;
background-color: var(–background-color);
color: var(–text-color);
line-height: 1.6;
margin: 0;
padding: 20px;
}
.container {
max-width: 1000px;
margin: 20px auto;
background-color: #fff;
padding: 30px;
border-radius: var(–border-radius);
box-shadow: var(–shadow);
}
h1, h2, h3 {
color: var(–primary-color);
margin-bottom: 1em;
}
h1 {
text-align: center;
font-size: 2.5em;
margin-bottom: 1.5em;
}
h2 {
font-size: 1.8em;
border-bottom: 2px solid var(–primary-color);
padding-bottom: 0.3em;
margin-top: 1.5em;
}
h3 {
font-size: 1.3em;
margin-top: 1.2em;
}
.loan-calc-container {
background-color: var(–background-color);
padding: 25px;
border-radius: var(–border-radius);
margin-bottom: 30px;
box-shadow: inset 0 2px 4px rgba(0,0,0,0.05);
}
.input-group {
margin-bottom: 20px;
text-align: left;
}
.input-group label {
display: block;
margin-bottom: 8px;
font-weight: bold;
color: #555;
}
.input-group input[type=”number”],
.input-group select {
width: calc(100% – 22px);
padding: 12px;
border: 1px solid #ccc;
border-radius: var(–border-radius);
font-size: 1em;
box-sizing: border-box;
}
.input-group .helper-text {
font-size: 0.85em;
color: #777;
margin-top: 5px;
display: block;
}
.error-message {
color: red;
font-size: 0.9em;
margin-top: 5px;
display: none; /* Hidden by default */
}
.button-group {
display: flex;
justify-content: space-between;
margin-top: 25px;
gap: 15px;
}
button {
padding: 12px 20px;
border: none;
border-radius: var(–border-radius);
cursor: pointer;
font-size: 1em;
transition: background-color 0.3s ease;
font-weight: bold;
}
.primary-button {
background-color: var(–primary-color);
color: white;
flex-grow: 1;
}
.primary-button:hover {
background-color: #003366;
}
.secondary-button {
background-color: #6c757d;
color: white;
}
.secondary-button:hover {
background-color: #5a6268;
}
.result-section {
margin-top: 30px;
padding: 25px;
background-color: var(–primary-color);
color: white;
border-radius: var(–border-radius);
text-align: center;
box-shadow: 0 2px 8px rgba(0, 0, 0, 0.2);
}
.result-section h3 {
color: white;
margin-bottom: 15px;
}
.main-result {
font-size: 2.2em;
font-weight: bold;
margin-bottom: 10px;
display: inline-block;
padding: 10px 20px;
background-color: rgba(255,255,255,0.2);
border-radius: var(–border-radius);
}
.intermediate-results {
font-size: 1.1em;
margin-top: 20px;
display: flex;
justify-content: center;
gap: 20px;
flex-wrap: wrap;
}
.intermediate-results div {
background-color: rgba(255,255,255,0.15);
padding: 10px 15px;
border-radius: var(–border-radius);
}
.intermediate-results span {
font-weight: bold;
}
.formula-explanation {
font-size: 0.9em;
color: rgba(255, 255, 255, 0.8);
margin-top: 20px;
text-align: left;
}
table {
width: 100%;
border-collapse: collapse;
margin-top: 20px;
margin-bottom: 30px;
box-shadow: var(–shadow);
}
th, td {
padding: 12px;
text-align: left;
border: 1px solid #ddd;
}
th {
background-color: #e9ecef;
color: #333;
font-weight: bold;
}
td {
background-color: #fff;
}
tr:nth-child(even) td {
background-color: #f8f9fa;
}
caption {
font-size: 1.1em;
margin-bottom: 10px;
font-weight: bold;
color: #555;
text-align: left;
}
canvas {
display: block;
margin: 20px auto;
border: 1px solid #ddd;
border-radius: var(–border-radius);
background-color: #fff;
}
.article-content {
margin-top: 40px;
padding-top: 30px;
border-top: 1px solid #eee;
}
.article-content p {
margin-bottom: 1.2em;
}
.article-content ul, .article-content ol {
margin-left: 20px;
margin-bottom: 1.2em;
}
.article-content li {
margin-bottom: 0.6em;
}
.faq-item {
margin-bottom: 15px;
}
.faq-item h3 {
cursor: pointer;
color: var(–primary-color);
margin-bottom: 5px;
font-size: 1.1em;
}
.faq-item p {
display: none; /* Hidden by default */
margin-top: 5px;
font-size: 0.95em;
color: #555;
}
.related-links ul {
list-style: none;
padding: 0;
}
.related-links li {
margin-bottom: 10px;
}
.related-links a {
color: var(–primary-color);
text-decoration: none;
font-weight: bold;
}
.related-links a:hover {
text-decoration: underline;
}
@media (max-width: 600px) {
.container {
padding: 20px;
}
h1 {
font-size: 2em;
}
.result-section {
padding: 20px;
}
.main-result {
font-size: 1.8em;
}
.intermediate-results {
flex-direction: column;
align-items: center;
}
.button-group {
flex-direction: column;
}
button {
width: 100%;
}
}

Accurately determine the appropriate tidal volume for mechanical ventilation based on patient weight using our expert guide and calculator.

Tidal Volume Calculator

Enter the patient’s weight to calculate the recommended tidal volume. This calculator uses a standard guideline of 6-8 mL/kg of ideal body weight.

Tidal Volume Calculation Explained

Tidal volume (Vt) is the amount of air that moves in or out of the lungs with each relaxed breath. In mechanical ventilation, it’s a crucial parameter set by healthcare professionals to ensure adequate gas exchange while minimizing lung injury. The calculation of tidal volume by weight is a standard practice to personalize ventilation settings based on patient size.

Who Uses Tidal Volume Calculations?

This calculation is primarily used by anesthesiologists, critical care physicians, respiratory therapists, and nurses managing patients requiring mechanical ventilation. It’s essential in intensive care units (ICUs), operating rooms (ORs), and emergency settings.

Common Misconceptions

A common misconception is that any tidal volume calculation is universally applicable. However, patient-specific factors, lung mechanics, and the goal of ventilation (e.g., lung protection vs. adequate CO2 removal) heavily influence the final settings. Another mistake is solely relying on total body weight without considering ideal body weight for significantly overweight or underweight patients.

Tidal Volume by Weight Formula and Mathematical Explanation

The fundamental principle behind calculating tidal volume by weight is to provide a volume of air that is proportional to the patient’s lung capacity, which generally correlates with body size. The most common guideline uses a range of 6 to 8 milliliters (mL) of tidal volume per kilogram (kg) of ideal body weight (IBW) or sometimes, for simplicity in non-obese patients, total body weight.

Step-by-Step Derivation

1. Determine Patient Weight: Obtain the patient’s accurate weight, preferably in kilograms. If the weight is in pounds, convert it to kilograms by dividing by 2.20462.
2. Calculate Ideal Body Weight (IBW) (Optional but Recommended): For a more precise calculation, especially in cases of obesity or malnutrition, ideal body weight is often preferred. Standard formulas exist for calculating IBW based on sex and height. For this calculator’s simplification, we’ll use total body weight if the user doesn’t specify IBW calculations separately, but acknowledge its importance.
3. Select Tidal Volume Factor: Choose a factor within the recommended range of 6-8 mL/kg. The lower end (6 mL/kg) is often used for lung protective ventilation strategies, especially in patients with Acute Respiratory Distress Syndrome (ARDS), to minimize barotrauma and volutrauma. The higher end (8 mL/kg) might be used when adequate ventilation (CO2 removal) is a priority and lung injury risk is lower.
4. Calculate Minimum Tidal Volume: Multiply the patient’s weight (in kg) by the minimum factor (6 mL/kg).
   Minimum Vt = Weight (kg) × 6 mL/kg
5. Calculate Maximum Tidal Volume: Multiply the patient’s weight (in kg) by the maximum factor (8 mL/kg).
   Maximum Vt = Weight (kg) × 8 mL/kg
6. Determine Final Tidal Volume: The final chosen tidal volume will be a value within the calculated minimum and maximum range, determined by clinical judgment.

Variable Explanations

Variable	Meaning	Unit	Typical Range
Patient Weight	The measured weight of the patient.	Kilograms (kg) or Pounds (lbs)	Varies widely
Ideal Body Weight (IBW)	Estimated weight a person would be at a given height if they were at a healthy weight. Crucial for obese or underweight patients.	Kilograms (kg)	Calculated based on height and sex (e.g., ~76.2 kg for a 5’10” male using Devine formula)
Tidal Volume (Vt)	The volume of air inhaled or exhaled in a single breath during normal breathing or mechanical ventilation.	Milliliters (mL)	Calculated range, typically 300-700 mL for adults
Tidal Volume Factor	A multiplier used to calculate Vt based on weight.	mL/kg	6-8 mL/kg (standard)

Practical Examples (Real-World Use Cases)

Example 1: Standard Adult Male Patient

Scenario: A 75 kg adult male patient is admitted to the ICU with pneumonia and requires mechanical ventilation. The clinical team decides to implement lung protective ventilation.

• Patient Weight: 75 kg
• Chosen Tidal Volume Factor: 6 mL/kg (for lung protection)

Calculation:

• Minimum Recommended Vt = 75 kg × 6 mL/kg = 450 mL
• Maximum Recommended Vt = 75 kg × 8 mL/kg = 600 mL

Result Interpretation: The recommended tidal volume range is 450-600 mL. For lung protective ventilation, the team would likely set the initial tidal volume at 450 mL. They would monitor the patient’s respiratory rate, blood gases (PaCO2), and airway pressures to ensure adequate ventilation and avoid lung injury. If PaCO2 is too high, they might increase Vt towards the upper end of the range or increase the respiratory rate.

Example 2: Obese Patient

Scenario: A 130 kg patient with obstructive sleep apnea develops respiratory failure and needs mechanical ventilation. Using total body weight might lead to excessive lung volumes.

• Patient Total Body Weight: 130 kg
• Estimated Ideal Body Weight (IBW): Let’s assume a calculated IBW for this patient (based on height/sex) is 70 kg.
• Chosen Tidal Volume Factor: 7 mL/kg (balanced approach)

Calculation (using IBW):

• Minimum Recommended Vt = 70 kg × 6 mL/kg = 420 mL
• Maximum Recommended Vt = 70 kg × 8 mL/kg = 560 mL

Result Interpretation: By using the Ideal Body Weight, the calculated tidal volume range (420-560 mL) is significantly lower than what would be calculated using total body weight (130 kg * 6-8 mL/kg = 780-1040 mL). This prevents overdistending the patient’s lungs, which are more vulnerable in obese individuals. The initial Vt setting would likely be around 420-560 mL, with close monitoring.

How to Use This Tidal Volume Calculator

Our Tidal Volume Calculator simplifies the process of determining appropriate ventilation settings based on patient weight. Follow these steps for accurate results:

Step-by-Step Instructions

1. Enter Patient Weight: Input the patient’s weight in the “Patient Weight” field.
2. Select Weight Unit: Choose “Kilograms (kg)” or “Pounds (lbs)” from the dropdown menu. If you select pounds, the calculator will automatically convert it to kilograms for the calculation.
3. Adjust Tidal Volume Factors (Optional): The default factors are set to 6 mL/kg (minimum) and 8 mL/kg (maximum), representing the standard guideline for lung protective ventilation. You can adjust these if your clinical protocol or patient’s condition requires different parameters (e.g., using 5-7 mL/kg for severe ARDS). Ensure you enter valid numbers greater than zero.
4. Click “Calculate Tidal Volume”: The calculator will instantly display the results.

How to Read Results

• Ideal Body Weight: Shows the estimated ideal body weight in kg, which is a critical reference, especially for non-standard body types.
• Minimum Recommended Vt: Displays the lower end of the tidal volume range (calculated using the minimum factor). This is often the starting point for lung protective strategies.
• Maximum Recommended Vt: Displays the upper end of the tidal volume range (calculated using the maximum factor).
• Primary Result (Recommended Tidal Volume): While the calculator shows a range, the system provides a suggested value within that range or highlights the range itself. The final decision on the exact tidal volume rests with the clinician.

Decision-Making Guidance

The calculated range serves as a guideline. Clinicians must consider:

• Lung Protective Ventilation (LPV): For conditions like ARDS, start at the lower end (6 mL/kg IBW).
• CO2 Elimination: If the patient has hypercapnia (high CO2) and no contraindications, you might titrate towards the higher end (up to 8 mL/kg IBW) or increase respiratory rate.
• Airway Pressures: Monitor Plateau Pressure (Pplat) and Peak Inspiratory Pressure (PIP). If pressures are too high (>30 cmH2O), reduce Vt or adjust other ventilator settings.
• Patient Condition: Underlying lung disease, patient comfort, and synchrony with the ventilator are vital.

The “Copy Results” button allows you to easily transfer these calculations and assumptions for documentation. Use the “Reset” button to start fresh with default values.

Key Factors That Affect Tidal Volume Results

While weight is the primary determinant for calculating tidal volume, several other clinical factors critically influence the final ventilator settings and patient outcomes. These factors necessitate a clinician’s judgment beyond the raw calculation:

1. Acute Respiratory Distress Syndrome (ARDS): Patients with ARDS often have stiff, non-compliant lungs (low lung volumes). Lung protective ventilation strategies recommend using lower tidal volumes (e.g., 4-6 mL/kg IBW) and potentially lower PEEP (Positive End-Expiratory Pressure) to avoid further lung injury (barotrauma and volutrauma).
2. Obesity: As highlighted in the examples, total body weight is a poor predictor of lung size in obese patients. Using Ideal Body Weight (IBW) or even Adjusted Body Weight (ABW) is crucial to avoid over-inflation and ventilator-induced lung injury (VILI).
3. Underweight or Cachexia: Conversely, severely underweight patients may have smaller lung volumes than predicted by standard IBW formulas, requiring careful titration.
4. Bronchospasm and Airway Obstruction: Conditions like asthma or COPD can lead to dynamic hyperinflation and air trapping. While Vt might be calculated based on weight, clinicians must closely watch for auto-PEEP and prolonged expiratory times, sometimes adjusting inspiratory flow patterns or sedation.
5. Pulmonary Compliance: Reduced lung compliance (stiffness) from conditions like pulmonary fibrosis or pneumonia requires lower tidal volumes to keep pressures within safe limits. High compliance might allow for slightly larger tidal volumes if needed for CO2 removal.
6. Neuromuscular Diseases: Conditions affecting respiratory muscles (e.g., Guillain-Barré syndrome, myasthenia gravis) can lead to respiratory muscle weakness and reduced ability to clear secretions, potentially influencing the goal of ventilation and the choice of Vt.
7. Hemodynamic Stability: High PEEP and large tidal volumes can sometimes impede venous return, affecting cardiac output. Ventilator settings must be balanced against the patient’s hemodynamic status.
8. Intracranial Pressure (ICP): In patients with elevated ICP, managing CO2 levels is critical. Hyperventilation (lowering PaCO2) can temporarily reduce ICP, but this is often done cautiously and may influence the target ventilation strategy, potentially leading to higher respiratory rates rather than simply higher tidal volumes.

Frequently Asked Questions (FAQ)

What is the difference between Ideal Body Weight (IBW) and Total Body Weight (TBW) for Vt calculation?

Ideal Body Weight (IBW) is an estimate of a healthy weight for a person of a specific height and sex. Total Body Weight (TBW) is the actual weight measured. IBW is preferred for Vt calculation, especially in obese or underweight patients, because it better reflects lung capacity and helps prevent lung over-distension or under-ventilation.

Why is a range (6-8 mL/kg) used for tidal volume?

The range allows for clinical flexibility. The lower end (6 mL/kg) is emphasized for lung protective ventilation (LPV) in conditions like ARDS to minimize ventilator-induced lung injury (VILI). The higher end (8 mL/kg) may be used when adequate CO2 removal is critical and the risk of VILI is deemed lower, based on patient’s lung mechanics and clinical status.

Can I use this calculator for pediatric patients?

This calculator is primarily designed for adults. Pediatric patients, especially neonates and infants, have different physiological parameters and require specialized ventilation calculations (often based on specific weight-based formulas or even flow-by ventilation techniques) determined by pediatric critical care specialists.

What happens if the tidal volume is set too high or too low?

Setting tidal volume too high can lead to volutrauma (overstretching the lungs) and barotrauma (lung injury due to high pressure), potentially causing Ventilator-Induced Lung Injury (VILI). Setting it too low may result in inadequate ventilation (hypoventilation), leading to CO2 retention (hypercapnia) and respiratory acidosis.

How often should tidal volume settings be reassessed?

Tidal volume settings should be reassessed regularly, at least every 4-8 hours, or whenever there is a significant change in the patient’s condition, lung mechanics (compliance, resistance), or gas exchange requirements. Continuous monitoring of airway pressures and blood gases is essential.

Does height affect tidal volume calculations?

Height is primarily used to calculate Ideal Body Weight (IBW). While the Vt calculation itself uses weight (preferably IBW), height is an indirect but important factor in determining the appropriate target weight for ventilation, especially for patients with non-standard body compositions.

What is lung protective ventilation?

Lung protective ventilation (LPV) is a strategy used in mechanical ventilation to minimize ventilator-induced lung injury (VILI). Key components include using low tidal volumes (typically 4-6 mL/kg IBW), appropriate PEEP levels, and limiting peak airway pressures and driving pressures.

What should I do if my patient’s CO2 levels remain high despite using the maximum recommended tidal volume?

If CO2 levels (PaCO2) are still high after setting Vt at the upper limit (e.g., 8 mL/kg IBW), consider increasing the respiratory rate, optimizing PEEP, ensuring adequate sedation (to prevent patient-ventilator asynchrony), or evaluating for other causes of hypoventilation. In some cases, permissive hypercapnia may be accepted if pressures are too high to increase Vt further.

var ctx = document.getElementById(‘tidalVolumeChart’).getContext(‘2d’);
var tidalVolumeChart = new Chart(ctx, {
type: ‘line’,
data: {
labels: [], // Will be populated by updateChart
datasets: [{
label: ‘Minimum Vt (mL)’,
borderColor: ‘rgba(255, 99, 132, 1)’,
backgroundColor: ‘rgba(255, 99, 132, 0.1)’,
fill: false,
data: [], // Will be populated by updateChart
tension: 0.1
}, {
label: ‘Maximum Vt (mL)’,
borderColor: ‘rgba(54, 162, 235, 1)’,
backgroundColor: ‘rgba(54, 162, 235, 0.1)’,
fill: false,
data: [], // Will be populated by updateChart
tension: 0.1
}]
},
options: {
responsive: true,
maintainAspectRatio: false,
scales: {
x: {
title: {
display: true,
text: ‘Patient Weight (kg)’
}
},
y: {
title: {
display: true,
text: ‘Tidal Volume (mL)’
},
beginAtZero: true
}
},
plugins: {
title: {
display: true,
text: ‘Tidal Volume Range vs. Patient Weight’
}
}
}
});

function updateChart() {
var weightInput = document.getElementById(‘patientWeight’);
var weightUnitSelect = document.getElementById(‘weightUnit’);
var tvMinFactorInput = document.getElementById(‘tvMinFactor’);
var tvMaxFactorInput = document.getElementById(‘tvMaxFactor’);

var weight = parseFloat(weightInput.value);
var unit = weightUnitSelect.value;
var minFactor = parseFloat(tvMinFactorInput.value);
var maxFactor = parseFloat(tvMaxFactorInput.value);

// Clear previous data
tidalVolumeChart.data.labels = [];
tidalVolumeChart.data.datasets[0].data = [];
tidalVolumeChart.data.datasets[1].data = [];

if (!isNaN(weight) && weight > 0 && !isNaN(minFactor) && minFactor > 0 && !isNaN(maxFactor) && maxFactor > 0) {
var baseWeightKg = (unit === ‘lbs’) ? weight / 2.20462 : weight;
var weights = [];
var minVts = [];
var maxVts = [];

// Generate data points for a range of weights around the input weight
var startWeight = Math.max(1, baseWeightKg – 30);
var endWeight = baseWeightKg + 30;
var step = (endWeight – startWeight) / 10; // 11 points for the line

for (var w = startWeight; w 0) {
weights.push(parseFloat(w.toFixed(1)));
minVts.push(w * minFactor);
maxVts.push(w * maxFactor);
}
}

tidalVolumeChart.data.labels = weights.map(function(w) { return w.toFixed(0); });
tidalVolumeChart.data.datasets[0].data = minVts;
tidalVolumeChart.data.datasets[1].data = maxVts;
}

tidalVolumeChart.update();
}

function toggleFaq(element) {
var content = element.nextElementSibling;
if (content.style.display === “block”) {
content.style.display = “none”;
} else {
content.style.display = “block”;
}
}

function calculateTidalVolume() {
var weightInput = document.getElementById(‘patientWeight’);
var weightUnitSelect = document.getElementById(‘weightUnit’);
var tvMinFactorInput = document.getElementById(‘tvMinFactor’);
var tvMaxFactorInput = document.getElementById(‘tvMaxFactor’);

var weightError = document.getElementById(‘weightError’);
var tvMinFactorError = document.getElementById(‘tvMinFactorError’);
var tvMaxFactorError = document.getElementById(‘tvMaxFactorError’);

var mainResultDiv = document.getElementById(‘mainResult’);
var idealBodyWeightDiv = document.getElementById(‘idealBodyWeight’);
var minVtDiv = document.getElementById(‘minVt’);
var maxVtDiv = document.getElementById(‘maxVt’);

var weight = parseFloat(weightInput.value);
var unit = weightUnitSelect.value;
var minFactor = parseFloat(tvMinFactorInput.value);
var maxFactor = parseFloat(tvMaxFactorInput.value);

// Reset error messages
weightError.style.display = ‘none’;
tvMinFactorError.style.display = ‘none’;
tvMaxFactorError.style.display = ‘none’;

// Validation
var isValid = true;
if (isNaN(weight) || weight <= 0) {
weightError.style.display = 'block';
isValid = false;
}
if (isNaN(minFactor) || minFactor <= 0) {
tvMinFactorError.style.display = 'block';
isValid = false;
}
if (isNaN(maxFactor) || maxFactor maxFactor) {
tvMinFactorError.style.display = ‘block’;
tvMaxFactorError.style.display = ‘block’;
tvMinFactorError.textContent = ‘Min factor cannot be greater than max factor.’;
tvMaxFactorError.textContent = ‘Max factor cannot be less than min factor.’;
isValid = false;
}

if (!isValid) {
mainResultDiv.innerHTML = ‘– mL’;
idealBodyWeightDiv.innerHTML = ‘– kg’;
minVtDiv.innerHTML = ‘– mL’;
maxVtDiv.innerHTML = ‘– mL’;
return;
}

var weightKg = (unit === ‘lbs’) ? weight / 2.20462 : weight;
var minVt = weightKg * minFactor;
var maxVt = weightKg * maxFactor;

// For simplicity, IBW is presented as the current weight in kg if lbs were used for input,
// or the input weight if kg was used. A true IBW calculation requires height/sex.
idealBodyWeightDiv.innerHTML = weightKg.toFixed(1) + ‘ kg’;
minVtDiv.innerHTML = minVt.toFixed(0) + ‘ mL’;
maxVtDiv.innerHTML = maxVt.toFixed(0) + ‘ mL’;

// Display a representative value or the range
// Let’s display the midpoint as the primary result for simplicity if range is calculated
var avgVt = (minVt + maxVt) / 2;
mainResultDiv.innerHTML = avgVt.toFixed(0) + ‘ mL’;
// Optionally, you could display the range itself:
// mainResultDiv.innerHTML = minVt.toFixed(0) + ‘ – ‘ + maxVt.toFixed(0) + ‘ mL’;

updateChart(); // Update the chart after calculation
}

function resetCalculator() {
document.getElementById(‘patientWeight’).value = ”;
document.getElementById(‘weightUnit’).value = ‘kg’;
document.getElementById(‘tvMinFactor’).value = ‘6’;
document.getElementById(‘tvMaxFactor’).value = ‘8’;

document.getElementById(‘weightError’).style.display = ‘none’;
document.getElementById(‘tvMinFactorError’).style.display = ‘none’;
document.getElementById(‘tvMaxFactorError’).style.display = ‘none’;

document.getElementById(‘mainResult’).innerHTML = ‘– mL’;
document.getElementById(‘idealBodyWeight’).innerHTML = ‘– kg’;
document.getElementById(‘minVt’).innerHTML = ‘– mL’;
document.getElementById(‘maxVt’).innerHTML = ‘– mL’;

updateChart(); // Reset chart
}

function copyResults() {
var mainResult = document.getElementById(‘mainResult’).innerText;
var ibw = document.getElementById(‘idealBodyWeight’).innerText;
var minVt = document.getElementById(‘minVt’).innerText;
var maxVt = document.getElementById(‘maxVt’).innerText;

var formula = “Tidal Volume (Vt) = Weight (kg) × Factor (mL/kg)”;
var assumptions = “Factors Used: Min ” + document.getElementById(‘tvMinFactor’).value + ” mL/kg, Max ” + document.getElementById(‘tvMaxFactor’).value + ” mL/kg.”;

var textToCopy = “Tidal Volume Calculation Results:\n\n”;
textToCopy += “Recommended Tidal Volume (Vt): ” + mainResult + “\n”;
textToCopy += “Ideal Body Weight: ” + ibw + “\n”;
textToCopy += “Minimum Recommended Vt: ” + minVt + “\n”;
textToCopy += “Maximum Recommended Vt: ” + maxVt + “\n\n”;
textToCopy += “Formula: ” + formula + “\n”;
textToCopy += “Assumptions: ” + assumptions + “\n”;

if (navigator.clipboard && window.isSecureContext) {
navigator.clipboard.writeText(textToCopy).then(function() {
alert(‘Results copied to clipboard!’);
}).catch(function(err) {
console.error(‘Failed to copy text: ‘, err);
// Fallback for older browsers or insecure contexts
var textArea = document.createElement(“textarea”);
textArea.value = textToCopy;
textArea.style.position = “fixed”;
textArea.style.left = “-9999px”;
document.body.appendChild(textArea);
textArea.focus();
textArea.select();
try {
document.execCommand(‘copy’);
alert(‘Results copied to clipboard!’);
} catch (err) {
alert(‘Failed to copy. Please copy manually.’);
}
document.body.removeChild(textArea);
});
} else {
// Fallback for browsers that don’t support clipboard API or insecure context
var textArea = document.createElement(“textarea”);
textArea.value = textToCopy;
textArea.style.position = “fixed”;
textArea.style.left = “-9999px”;
document.body.appendChild(textArea);
textArea.focus();
textArea.select();
try {
document.execCommand(‘copy’);
alert(‘Results copied to clipboard!’);
} catch (err) {
alert(‘Failed to copy. Please copy manually.’);
}
document.body.removeChild(textArea);
}
}

// Initial chart update on load
document.addEventListener(‘DOMContentLoaded’, function() {
updateChart();
});