1. What is Total Lung Capacity?

Total Lung Capacity (TLC) is the maximum volume of air the lungs can hold. It is the sum of vital capacity (VC) and residual volume (RV). TLC is an important measurement in pulmonary function testing.

2. How Does the Calculator Work?

The calculator uses the simple formula:

Where:

• \( TLC \) — Total Lung Capacity (L)
• \( VC \) — Vital Capacity (L)
• \( RV \) — Residual Volume (L)

Explanation: Vital capacity is the maximum amount of air a person can expel from the lungs after maximum inhalation, while residual volume is the amount of air remaining in the lungs after maximal exhalation.

3. Importance of TLC Measurement

Details: TLC measurement helps diagnose and monitor restrictive and obstructive lung diseases. Abnormal TLC values may indicate conditions like pulmonary fibrosis, COPD, or emphysema.

4. Using the Calculator

Tips: Enter vital capacity and residual volume in liters. Both values must be positive numbers. Typical adult values are VC: 3-5L, RV: 1-1.5L, resulting in TLC of 4-6.5L.

5. Frequently Asked Questions (FAQ)

Q1: How is TLC typically measured?
A: TLC is most accurately measured by body plethysmography or gas dilution techniques, though it can be estimated from VC and RV measurements.

Q2: What affects TLC values?
A: TLC varies with age, sex, height, and ethnicity. It decreases with age and is generally higher in males and taller individuals.

Q3: What's the difference between TLC and VC?
A: VC is the amount of air that can be forcibly exhaled after maximal inhalation, while TLC includes both VC and the residual volume that always remains in the lungs.

Q4: When is TLC increased or decreased?
A: TLC is increased in obstructive diseases like emphysema and decreased in restrictive diseases like pulmonary fibrosis.

Q5: Can this calculator be used for children?
A: Yes, but normal values are much smaller for children and must be interpreted using pediatric reference ranges.