FEV1/FVC ratio

(noun)

The ratio between forced expiratory volume and forced vital capacity, which is used to measure the level of obstruction in the lungs.

Related Terms

Examples of FEV1/FVC ratio in the following topics:

  • Lung Capacity and Volume

    • An FEV1/FVC ratio of >80% indicates a restrictive lung disease like pulmonary fibrosis or infant respiratory distress syndrome.
    • The most widely used diagnostic application for lung capacities is the ratio between forced expiratory volume (FEV1) and forced vital capacity (FVC).
    • An FEV1/FVC ratio that is greater than .8 indicates a normal lung with generally healthy function, however a ratio below .8 indicates a significant degree of airway obstruction to suggest COPD.
    • The FEV1/FVC ratio naturally falls as humans age, however smoking (the cause of COPD) will cause much larger decreases in FEV1/FVC ratio than what is normal.
    • Those that quit smoking will not experience a regain the FEV1/FVC ratio lost from smoking, however their rate of FEV1/FVC ratio decline will slow to normal, and their life expectancy will be less impacted.

  • Lung Volumes and Capacities

    • An important measurement taken during spirometry is the forced expiratory volume (FEV), which measures how much air can be forced out of the lung over a specific period, usually one second (FEV1).
    • In addition, the forced vital capacity (FVC), which is the total amount of air that can be forcibly exhaled, is measured.
    • The ratio of these values (FEV1/FVC ratio) is used to diagnose lung diseases including asthma, emphysema, and fibrosis.
    • If the FEV1/FVC ratio is high, the lungs are not compliant (meaning they are stiff and unable to bend properly); the patient probably has lung fibrosis.
    • Conversely, when the FEV1/FVC ratio is low, there is resistance in the lung that is characteristic of asthma.

  • The Work of Breathing

    • Forced or functional vital capacity (FVC), which is the amount of air that can be forcibly exhaled after taking the deepest breath possible, is much lower than in normal patients; the time it takes to exhale most of the air is greatly prolonged .
    • The ratio of FEV1 (the amount of air that can be forcibly exhaled in one second after taking a deep breath) to FVC (the total amount of air that can be forcibly exhaled) can be used to diagnose whether a person has restrictive or obstructive lung disease.

  • Chronic Obstructive Pulmonary Disease (COPD)

    • The diagnosis of COPD is confirmed by spirometry, a test that measures the forced expiratory volume in one second (FEV1), which is the greatest volume of air that can be breathed out in the first second of a large breath.
    • Spirometry also measures the forced vital capacity (FVC), which is the greatest volume of air that can be breathed out in a whole, large breath.