Lung function tests (also called pulmonary function tests) are done
to check how well your lungs are working. The test may be done to find the
cause of breathing problems, diagnose lung diseases, or find out how well
treatment for a lung problem is working.
There are many types of lung function tests.
Spirometry measures how much and how quickly you
can move air out of your lungs. A spirometry test can measure:
Forced expiratory volume (FEV), which is the amount of
air you can exhale with force in one breath.
Peak expiratory flow
(PEF), which is how much air you can breathe out when you try your hardest.
Total lung capacity
(TLC), which is the amount of air in your lungs after you inhale as deeply as
Gas diffusion tests measure the
amount of oxygen and other gases that cross the lungs' air sacs (alveoli) per
minute. The results help determine how well gases are being absorbed into your
blood from your lungs.
Inhalation challenge tests help
identify substances that may be causing severe respiratory
allergies or asthma. These tests are also called provocation studies.