Spirometry is the best test to assess lung function. It
often is used to evaluate a person who has a chronic cough and sputum (
mucus) production and a history of risk factors for
chronic obstructive pulmonary disease (COPD), even if
shortness of breath is not present. It is also used to find out whether a
specific therapy has improved lung function or whether your lung disease is
Spirometry testing may be done in your doctor's
office or in a hospital. During the test:
A tube is connected to the
You place your mouth on the tube and take the deepest
You then blow out as hard and as fast as
This should be repeated several times during the visit to
ensure accurate results.
This test measures the flow and amount of
air when you breathe in and out as deeply and forcefully as you can. For people
with COPD, the test is divided into:
Forced expiratory volume in 1 second (FEV1), the
amount of air breathed out as forcefully as possible in 1 second. The FEV1
value can help your doctor estimate the severity of COPD.
vital capacity (FVC), the amount of air that can be forcibly breathed out after
taking a deep breath.
The normal values for each of the measurements depend on your
age, height, gender, and race. This is known as the predicted value. People
with COPD typically have a reduction in FEV1 and may also have a reduction in
FVC. A reduction in the ratio of FEV1 to the FVC points to airway obstruction,
including COPD and
These measurements help your
doctor diagnose COPD and find out the severity of the
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