FEV1/FVC ratio

Definition

The FEV1/FVC ratio is a calculated ratio used in pulmonary function tests to assess the presence of obstructive and restrictive respiratory conditions. It represents the proportion of a person's vital capacity that they can exhale in the first second of forced expiration (FEV1) compared to their total forced vital capacity (FVC).

5 Must Know Facts For Your Next Test

1. A normal FEV1/FVC ratio is typically around 70-80% in healthy adults.
2. A decreased FEV1/FVC ratio indicates obstructive lung diseases such as asthma or chronic obstructive pulmonary disease (COPD).
3. An increased or normal FEV1/FVC ratio coupled with a reduced FVC suggests restrictive lung diseases like pulmonary fibrosis.
4. The test involves taking a deep breath and exhaling forcefully into a spirometer to measure both FEV1 and FVC.
5. The FEV1/FVC ratio helps differentiate between different types of respiratory disorders based on patterns of airflow limitation.

Review Questions

• What does a decreased FEV1/FVC ratio indicate about lung function?
• How is the FEV1/FVC ratio measured during a pulmonary function test?
• Why might an increased or normal FEV1/FVC ratio be seen in restrictive lung diseases?

Related terms

FEV1: Forced expiratory volume in one second, measuring how much air a person can forcefully exhale in one second.

FVC: Forced vital capacity, measuring the total amount of air exhaled during the entire forced expiratory maneuver.

Spirometer: A device used to measure lung function, specifically volumes and flow rates during breathing.