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Lung function means how well your lungs work. When you have
COPD, your lungs can't move as much air in and out as they should. And the more
serious your COPD is, the less air your lungs are able to move.
Spirometry tests are used to measure lung function.
They measure how much air you breathe out when you take long, deep breaths and
push the air out of your lungs. For people with COPD, the test measures how
well the lungs do two important jobs:
Your FEV1 and FVC numbers are lower than normal when you have COPD, and they get lower as the disease gets worse. These
numbers are usually stated in the form of a percentage.
glass of water. If the glass is full to the brim, it is 100% full. If it is
only half full, it is 50% full. And 33% means it is only one-third full, and so
on. Likewise, if your FEV1 is 50%, your lungs are able to handle only half as
much air as they should. If your FEV1 is 33%, your lungs are able to handle
even less—only a third as much. The lower your FEV1 percentage, the less air
your lungs are able to handle.
the FEV1 numbers for the various grades of COPD, according to the Global
Initiative for Chronic Obstructive Lung Disease (GOLD).1 The symptoms you have may vary from the symptoms listed below.
If you don't understand your lung
function numbers, ask your doctor to explain them for you. To help make the best treatment plan for you, your doctor will look at your FEV1, your symptoms, and what other health problems you have.
Global Initiative for Chronic Obstructive Lung Disease (2013). Global Strategy for the Diagnosis, Management, and Prevention of COPD. Available online: http://www.goldcopd.org/guidelines-global-strategy-for-diagnosis-management.html.
Current as of:
November 14, 2013
E. Gregory Thompson, MD - Internal Medicine & Ken Y. Yoneda, MD - Pulmonology
How this information was developed to help you make better health decisions.
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