Lung Compliance Calculator

Calculate lung compliance by measuring the change in lung volume relative to the change in transpulmonary pressure. This helps assess lung elasticity and respiratory function.

How to Use This Calculator

Enter the change in lung volume (ΔV) in milliliters
Enter the corresponding change in transpulmonary pressure (ΔP) in cm H₂O
Select whether you're calculating static or dynamic compliance
Click Calculate to see your lung compliance result and interpretation

Formula Used

Compliance = ΔV / ΔP

Where:

ΔV = Change in lung volume (mL)
ΔP = Change in transpulmonary pressure (cm H₂O)
Compliance = Lung compliance (mL/cm H₂O)

Example Calculation

Real-World Scenario:

A patient undergoing pulmonary function testing shows a volume change of 500 mL when the transpulmonary pressure increases from 5 to 10 cm H₂O. Calculate the lung compliance.

Given:

ΔV = 500 mL
ΔP = 10 - 5 = 5 cm H₂O
Compliance Type = Static

Calculation:

Compliance = 500 mL / 5 cm H₂O = 100 mL/cm H₂O

Result: Lung compliance is 100 mL/cm H₂O, which falls within the normal range (indicating healthy lung elasticity).

Why This Calculation Matters

Practical Applications

Diagnosing restrictive lung diseases (low compliance)
Identifying obstructive lung conditions (variable compliance)
Monitoring treatment effectiveness in respiratory disorders
Assessing lung function in critical care settings

Key Benefits

Quantifies lung elasticity objectively
Helps differentiate between disease types
Guides clinical decision-making
Monitors disease progression over time

Common Mistakes & Tips

Always ensure consistent units. Convert volume to milliliters and pressure to cm H₂O before calculation. Using different units (like liters and mmHg) without proper conversion will yield incorrect results.

Static compliance measures lung elasticity without airflow, while dynamic compliance includes airway resistance effects. Choose the appropriate type based on your measurement conditions for accurate interpretation.

Frequently Asked Questions

Normal static lung compliance ranges from 60-100 mL/cm H₂O. Dynamic compliance is typically 50-80 mL/cm H₂O. Values outside this range may indicate lung disease.

Restrictive diseases (like pulmonary fibrosis) show decreased compliance (stiff lungs), while obstructive diseases (like asthma) may show normal or increased compliance due to air trapping.

While true lung elasticity changes are often permanent, treatments can optimize lung function. Pulmonary rehabilitation, medications, and in some cases, lung volume reduction surgery may help improve effective compliance.

References & Disclaimer

Medical Disclaimer

This calculator is for educational purposes only and should not be used for clinical diagnosis or treatment decisions. Always consult with qualified healthcare professionals for medical advice and diagnosis. Lung compliance calculations should be interpreted by trained medical personnel in conjunction with comprehensive patient evaluation.

References

American Thoracic Society Guidelines - Comprehensive guidelines on pulmonary function testing
Merck Manual - Lung Compliance - Detailed medical information on lung mechanics
NCBI - Pulmonary Function Testing - Scientific basis for lung function measurements

Accuracy Notice

This calculator provides estimates based on the input values. Actual clinical measurements may vary due to patient-specific factors, measurement techniques, and equipment calibration. Results should be verified through professional pulmonary function testing.

About the Author

Kumaravel Madhavan

Web developer and data researcher creating accurate, easy-to-use calculators across health, finance, education, and construction and more. Works with subject-matter experts to ensure formulas meet trusted standards like WHO, NIH, and ISO.

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