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Last Updated: Aug 29, 2019
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Dr. Balachandar MPulmonologist • 19 Years Exp.DNB(Respireatory diseases), M.D
Pulmonary Function Tests
Pulmonary function tests (PFT’s) are breathing
tests to find out how well you move air in and
out of your lungs

Lung function tests can be used to:
■ Compare your lung function with known
standards that show how well your lungs should
be working.
■ Measure the effect of chronic diseases like
asthma, chronic obstructive lung disease
(COPD), or cystic fibrosis on lung function.
■ Identify early changes in lung function that
might show a need for a change in treatment.
■ Detect narrowing in the airways.
■ Decide if a medicine (such as a bronchodilator)
could be helpful to use.
■ Show whether exposure to substances in your
home or workplace have harmed your lungs.
■ Determine your ability to tolerate surgery and
medical procedures

What is spirometry?
Spirometry is one of the most commonly ordered
lung function tests. The spirometer measures
how much air you can breathe into your lungs
and how much air you can quickly blow out of
your lungs. This test is done by having you take
in a deep breath and then, as fast as you can,
blow out all of the air. You will be blowing into a
tube connected to a machine (spirometer).
The spirometry test is often repeated after
giving you a breathing medicine (bronchodilator)
to find out how much better you might breathe
with this type of medicine. You will be asked
to repeat this test two or three times to get an
accurate measure of your lung function. It can
take practice to be able to do spirometry well.
The staff person will work with you to learn how
to do the test correctly.
It usually takes 30 minutes to complete this test

What should I know before taking
this test?
■ You may be asked not to take your breathing
medicines before this test.
■ Instructions will be given on how to do this
test. If you do not understand them, ask the
technician to repeat them.
■ It takes effort to do this test and you may
become tired. This is expected.
■ If you become light-headed or dizzy during
this test, immediately stop blowing and let the
technician know