What are pulmonary function tests?
Pulmonary function tests (PFTs), also known as lung function tests, check how well your lungs are working. They can measure how quickly air moves in and out of your lungs and how much air your lungs can hold. Your doctor might also order these tests to learn how well your lungs move oxygen into your blood and how exercise affects your lungs. There are several types of pulmonary function tests, including spirometry, lung volumes, and others.
At Penn Pulmonology and Respiratory Care, these specialized, noninvasive tests are performed by pulmonary function therapists who are skilled at guiding you through each step of the process. Our therapists also work closely with your doctor throughout your diagnosis and treatment, so you get the therapies that help you breathe more comfortably.
When is a pulmonary function test required?
You might need pulmonary function testing if you have signs or symptoms of asthma, chronic obstructive pulmonary disease (COPD), pulmonary fibrosis, or other lung conditions. These may include:
- Shortness of breath
- Coughing
- Low oxygen levels
- Wheezing
- Repeated bronchitis
If you’re already receiving treatment for a lung disease, PFTs can determine how well your therapy is working or whether your lung disease is progressing. You might also need pulmonary function testing to check your lung function before surgery or if you have risk factors of lung disease. Let your doctor know if you’ve had recent surgeries or health conditions before you have a PFT.
What to expect during pulmonary function tests
Follow your health care provider’s instructions about how to prepare for your test, including whether you need to stop any of your medications. Generally, avoid exercise, a heavy meal, and tobacco use before your test. What to expect on the day of the test depends on the type of PFT you’re having. For some of these tests, you’ll wear a soft nose clip.
You’ll take a deep breath and exhale forcefully into a tube connected to a machine called a spirometer, which records how much air you breathe in and out. This is repeated a few times, sometimes after taking a bronchodilator or bronchoconstrictor medication. Spirometry is also used to create a flow-volume loop, which charts flow rates of the air you breathe out against your lung volumes.
For this test, you’ll sit in an enclosed space with clear walls while you take small panting breaths to measure how much air your lungs can hold.
This test uses sound waves to look at how air moves in and out of your lungs while you breathe into a mouthpiece. It’s often given to children and adults who can’t exhale strongly.
You’ll take a deep breath of a harmless gas with a tracing agent and hold it for a few seconds before breathing out. As you exhale, the tracer is measured to see how easily gases like oxygen move from your lungs to your blood.
As you inhale or exhale sharply into a mouthpiece, this test evaluates the force of air coming in and out of your lungs and identifies any respiratory muscular weakness.
A small device called a pulse oximeter is positioned on your fingertip and uses a light source to monitor the percentage of oxygen in your red blood cells and your resting heart rate. Sometimes this test is also done during a six-minute walk to compare your oxygen levels during exercise and at rest.
This blood test measures your oxygen and carbon dioxide levels, which show how well your lungs move oxygen into your bloodstream and carbon dioxide out.
You’ll walk on a treadmill or ride a stationary bike for 10 to 20 minutes as your heart rate, blood pressure, and blood oxygen levels are recorded. The test can let your doctor know if a problem with your lungs or heart is limiting your exercise ability.
Recovering from pulmonary function tests
Some people may feel lightheaded or dizzy after the test. If this happens, your health care provider will monitor you until the symptoms go away. Otherwise, you can go back to your usual activities.
Testing by expert respiratory therapists
At Penn Medicine, therapists certified in respiratory therapy and pulmonary function perform your PFT using the latest techniques. Interpretation of your pulmonary function test is done by one of our pulmonary physicians, who works with your therapists and other providers to give you an accurate diagnosis and specialized care for your condition. Our respiratory therapists also teach you about your condition and give you training that can improve your breathing, including how to use an inhaler, manage medications, and perform breathing exercises. We also offer smoking cessation programs to help you quit smoking.
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