Spirometry, which is also known as pulmonary function testing, is a tool for measuring lung function. Specifically, the test measures the volume (amount) and/or flow (speed) of air that can be inhaled or exhaled. Spirometry testing is a vital component for diagnosing occupational lung diseases and for assessing and monitoring such conditions as asthma and chronic obstructive pulmonary disease.
The lung diseases detected by spirometry are mostly caused by smoking, respiratory infections, and breathing in hazardous dusts, fumes, or vapors. For DOE workers, the spirometry test is used to measure lung function in individuals who have symptoms such as chronic cough, shortness of breath, and/or wheezing to help determine whether they have lung diseases that may have resulted from occupational exposures during work at DOE facilities. Workers with abnormal spirometry results are referred to their primary care physicians for further evaluation.
The test is performed by deeply inhaling and then forcefully exhaling into a spirometer (the machine that records the measurements). There are two measurements that are crucial in the interpretation of spirometry results.
The first measurement is the forced vital capacity (FVC). FVC is the total amount of air that can forcibly be blown out after a deep breath. The second measurement is the forced expiratory volume-one second (FEV1). FEV1 is the amount of air that an individual can forcibly blow out in one second. Another common value reported in a spirometry test is the ratio of FEV1 to FVC. In healthy middle-aged adults, the ratio should be above 70%; the normal value decreases with age. The table below shows normal and abnormal spirometry readings.
A reduction in FVC can be caused by restrictive lung disease (such as asbestosis). Abnormalities in the FEV1 and the FEV1/FVC result from a decrease in the air flow out of the lung. This decrease may be caused by obstructive lung diseases, such as silicosis, emphysema, and asthma. The table below provides an interpretation of spirometry results.
Spirometry Test | Normal | Abnormal |
FVC and FEV1 | Equal to or greater than 80%, or above the lower limit of normal using statistical testing | Mild 70-79% Moderate 60-69% Severe less than 50% |
FEV1/FVC | Equal to or greater than 70%, or above the lower limit of normal using statistical testing | Mild 60-69% Moderate 50-59% Severe less than 50% |
FOR ADDITIONAL INFORMATION:
Mary Fields, Program Manager