Pulmonary Function Tests Using Spirometry

Author: Scott A. Sheffield MS

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Forced Vital Capacity (FVC or FVC6) and Forced Expiratory Volume in one second (FEV1) are two pulmonary function tests that are routinely used to determine the health of the respiratory airways and lung tissues.

To obtain an  image descriptionFVC, a subject first inhales as much air as possible.

A person blows into a spirometer that is connected to a graph showing the forced expiratory volume (FEV) over time.
A person blows into a spirometer that is connected to a graph showing the forced expiratory volume (FEV) over time.
A person blows into a spirometer that is connected to a graph showing the forced expiratory volume (FEV) over time.
A person blows into a spirometer that is connected to a graph showing the forced expiratory volume (FEV) over time.
A person blows into a spirometer that is connected to a graph showing the forced expiratory volume (FEV) over time.
A person blows into a spirometer that is connected to a graph showing the forced expiratory volume (FEV) over time.
A person blows into a spirometer that is connected to a graph showing the forced expiratory volume (FEV) over time.
A person blows into a spirometer that is connected to a graph showing the forced expiratory volume (FEV) over time.
A person blows into a spirometer that is connected to a graph showing the forced expiratory volume (FEV) over time.
A person blows into a spirometer that is connected to a graph showing the forced expiratory volume (FEV) over time.
A person blows into a spirometer that is connected to a graph showing the forced expiratory volume (FEV) over time.
A person blows into a spirometer that is connected to a graph showing the forced expiratory volume (FEV) over time.
A person blows into a spirometer that is connected to a graph showing the forced expiratory volume (FEV) over time.
Forced Vital Capacity

The subject then exhales forcibly through a spirometer for a period of at least six (6) seconds, which nearly empties the lungs of air.

The image descriptionFEV1 is the volume of air that can be forcibly exhaled in one second after a maximal inhalation.

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A person blows into a spirometer that is connected to a graph showing the forced expiratory volume (FEV) over time.
A person blows into a spirometer that is connected to a graph showing the forced expiratory volume (FEV) over time.
A person blows into a spirometer that is connected to a graph showing the forced expiratory volume (FEV) over time.
A person blows into a spirometer that is connected to a graph showing the forced expiratory volume (FEV) over time.
A person blows into a spirometer that is connected to a graph showing the forced expiratory volume (FEV) over time.
Forced Expiratory Volume

The ratio of FEV1/FVC should be 75% or higher. Reduced values indicate an obstructive lung disease, such asthma, bronchitis, or COPD (chronic obstruc-tive pulmonary disease), which block normal airflow. Reduced values for both the FEV1 and FVC indicates a restrictive lung disease, such as pulmonary fibrosis or emphysema, which prevent the lungs from fully inflating.