Introduction to Spirometers & Lung Diseases
Pulmonary Function Tests Using Spirometry
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 FVC, a subject first inhales as much air as possible.
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 FEV1 is the volume of air that can be forcibly exhaled in one second after a maximal inhalation.
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.