1. What is FEV1/FVC Ratio?

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

2. How Does the Calculator Work?

The calculator uses the FEV1/FVC ratio formula:

Where:

• \( \text{FEV1} \) — Forced Expiratory Volume in 1 second (L)
• \( \text{FVC} \) — Forced Vital Capacity (L)

Explanation: The ratio compares the amount of air exhaled in the first second to the total amount of air that can be forcibly exhaled.

3. Importance of FEV1/FVC Ratio

Details: This ratio is crucial for diagnosing obstructive lung diseases like asthma and COPD. 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 (L). Both values must be positive numbers greater than zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is a normal FEV1/FVC ratio?
A: A normal FEV1/FVC ratio is typically above 0.70-0.75 (70-75%), though this can vary slightly with age, gender, and ethnicity.

Q2: What does a low FEV1/FVC ratio indicate?
A: A ratio below 0.70 typically indicates obstructive lung disease, where airflow is limited during exhalation.

Q3: What does a normal or high FEV1/FVC ratio with low FVC indicate?
A: This pattern may suggest restrictive lung disease, where lung expansion is limited.

Q4: How are FEV1 and FVC measured?
A: Both are measured using spirometry, where the patient takes a deep breath and exhales as forcefully and completely as possible into a spirometer.

Q5: Can the ratio be affected by other factors?
A: Yes, factors like patient effort, technique, age, height, and gender can influence the results. Proper testing technique is essential for accurate measurements.