1. What is FEV1/FVC Ratio?

The FEV1/FVC ratio is a measurement used in pulmonary function testing to assess for obstructive lung disease. It represents the proportion of a person's vital capacity that they are able to expire in the first second of forced expiration.

2. How Does the Calculator Work?

The calculator uses the FEV1/FVC ratio formula:

Where:

• \( FEV1 \) — Forced Expiratory Volume in 1 second (liters)
• \( FVC \) — Forced Vital Capacity (liters)

Explanation: The ratio compares the amount of air exhaled in the first second to the total amount exhaled during the forced vital capacity maneuver.

3. Importance of FEV1/FVC Ratio

Details: This ratio is crucial for diagnosing obstructive lung diseases such as asthma, COPD, and emphysema. A reduced FEV1/FVC ratio indicates airflow limitation and is a key criterion for diagnosing obstructive lung disorders.

4. Using the Calculator

Tips: Enter FEV1 and FVC values in liters. Both values must be positive numbers, and FVC should be greater than or equal to FEV1. The calculator will compute the ratio and provide interpretation based on standard clinical thresholds.

5. Frequently Asked Questions (FAQ)

Q1: What is a normal FEV1/FVC ratio?
A: A normal ratio is typically ≥70% in adults, though it may vary slightly by age, gender, and ethnicity.

Q2: What does a low FEV1/FVC ratio indicate?
A: A ratio below 70% suggests obstructive lung disease, where airflow is limited during expiration.

Q3: Can the ratio be greater than 100%?
A: No, since FEV1 cannot exceed FVC, the ratio should always be ≤100%.

Q4: How does age affect the FEV1/FVC ratio?
A: The ratio naturally decreases with age, so age-specific reference values are often used in clinical practice.

Q5: What's the difference between obstructive and restrictive patterns?
A: Obstructive pattern shows reduced FEV1/FVC ratio, while restrictive pattern shows normal ratio but reduced FVC and FEV1.