Pulmonary function tests are carried out when there's concern your lungs may not be functioning well or coping well under certain circumstances, such as when you're engaged in strenuous activity. Your doctor might also call for a test when they think you could have a lung-related health condition, such as lung fibrosis, bronchiectasis, lung cancer, or a pulmonary tumor. The tests measure your breathing capacity and how well your lungs fulfill the role of delivering oxygen to the rest of your body.
Preparing For Your Tests
There are certain steps your doctor may ask you to take in preparation for your pulmonary function testing appointment. You may be asked to temporarily stop taking certain medications, such as those used to treat asthma or chronic pain, as they may skew the results of the tests. You may also be asked to fast before your tests or consume only a light diet, as a full stomach can limit how much air your lungs can inhale per breath. Additionally, you may be asked to cut out caffeine, as caffeine can dilate your airways. You should wear loose fitting clothes that do not restrict your breathing, and you should inform the person carrying out the test of any changes to your health that have occurred since your last medical appointment.
3 Commonly Used Tests
Your doctor may suggest you have one or several types of pulmonary function tests depending on the exact reason you require the tests, because each test measures a different aspect of your overall lung function.
Spirometry is a commonly used test that measures the amount of air taken into your lungs and released during each breath and can help determine lung size. You'll have a mouthpiece fitted for this test, and your nose will be fitted with a clip to ensure you only breathe through your mouth.
Another commonly used test is the plethysmography test, which involves breathing into a mouthpiece in a sealed booth. This test can help your doctor establish the volume of gas in your lungs by measuring air pressure in the sealed booth.
Lastly, a diffusion capacity test is a useful indicator of how well the alveoli work. These are small air sacs in your lungs that facilitate the transfer of oxygen from your lungs into your bloodstream. For this test you will be asked to breathe in a range of different gases, and your doctor will measure how well your lungs cope with processing oxygen and filtering out byproducts.
Pulmonary function tests are considered low-risk, but some people may feel a little lightheaded during or after these tests. If you're preparing to undergo pulmonary functioning testing, discuss any concerns you have with your doctor beforehand to ensure you're as prepared as possible for your tests.