What are the types of pulmonary function tests?
Pulmonary function tests include:
- Spirometry sitting/supine
- Body plethysmography
- Methacholine inhalation challenge
- Six-minute walk test
- Exhaled nitric oxide test
- Arterial blood gas test
- Lung volume test
- Lung diffusion capacity
- Cardiopulmonary exercise test
- Oximetry with ambulation
- Respiratory muscle strength test
- Altitude simulation tests
- Exercise challenge (spirometry before and after)
- Shunt study (100% O₂)
- Maximal voluntary volume (MVV)
Spirometry is one of the most common lung function tests. During this test, you forcefully exhale and then inhale into a tube connected to a machine called a spirometer. The spirometer measures the amount of air you blew out of your lungs and then inhaled back into your lungs. You will be asked to repeat this test two or three times to get an accurate measure of your lung function. It takes approximately 30 minutes to complete this test.
Sometimes you may be given a breathing medication then asked to repeat the spirometry. This allows your doctor to assess improvement in your breathing caused by this medication.
Diffusion tests determine how well the oxygen you breathe in moves from your lungs to your blood. Like spirometry, this test is done by having you breathe into a mouthpiece connected to a machine. You will be asked to empty your lungs by gently breathing out as much air as you can. Then you will breathe in a quick but deep breath, hold your breath for 10 seconds, and then breathe out. It takes 15 minutes to complete this test.
Body plethysmography is used to determine how much air is in your lungs after you take in a deep breath, and how much air is left in your lungs after exhaling. Measuring the total amount of air your lungs can hold and the amount of air left in your lungs after you breathe out gives your healthcare provider information about how well your lungs are working.
This test requires that you sit in an enclosed plastic box that you can see through. You will be asked to wear a nose clip and you will be given instruction on how to breathe through a mouthpiece. The test takes about 15 minutes.