1. What is Total Lung Capacity?

Total Lung Capacity (TLC) is the maximum volume of air the lungs can hold after a maximum inhalation. It represents the sum of all lung volumes and is an important measurement in pulmonary function testing.

2. How Does the Calculator Work?

The calculator uses the TLC formula:

Where:

• \( IRV \) — Inspiratory Reserve Volume (additional air that can be inhaled after normal inspiration)
• \( TV \) — Tidal Volume (normal breathing volume)
• \( ERV \) — Expiratory Reserve Volume (additional air that can be exhaled after normal expiration)
• \( RV \) — Residual Volume (air remaining in lungs after maximum exhalation)

Explanation: The equation sums all lung volume components to determine the total capacity of the lungs.

3. Importance of Lung Capacity Measurement

Details: Measuring TLC is crucial for diagnosing restrictive lung diseases, monitoring lung function in various conditions, and assessing overall respiratory health.

4. Using the Calculator

Tips: Enter all four lung volume measurements in milliliters (mL). Values must be non-negative numbers obtained from pulmonary function tests.

5. Frequently Asked Questions (FAQ)

Q1: What is a normal TLC value?
A: Normal TLC values vary by age, gender, and body size but typically range from 4,000-6,000 mL in healthy adults.

Q2: How is TLC measured clinically?
A: TLC is typically measured using body plethysmography, helium dilution, or nitrogen washout techniques in pulmonary function laboratories.

Q3: What conditions affect TLC?
A: Restrictive lung diseases decrease TLC, while obstructive diseases may increase TLC due to air trapping.

Q4: Can TLC change over time?
A: Yes, TLC can change with age, lung diseases, surgical procedures, and certain medical treatments.

Q5: Is this calculator suitable for clinical diagnosis?
A: This calculator provides estimates only. Clinical diagnosis should be based on comprehensive pulmonary function testing under medical supervision.