What Are Pulmonary Function Test ?
Lung function tests, also called pulmonary (PULL-mun-ary) function tests, measure how well your lungs work. These tests are used to look for the cause of breathing problems, such as shortness of breath.
Pulmonary Function Test measure:
Doctors use pulmonary function tests to help diagnose conditions such as asthma, pulmonary fibrosis (scarring of the lung tissue), and COPD (chronic obstructive pulmonary disease).
Pulmonary function tests also are used to check the extent of damage caused by conditions such as pulmonary fibrosis and sarcoidosis (sar-koy-DOE-sis). Also, these tests may be used to check how well treatments, such as asthma medicines, are working.
Pulmonary function tests include breathing tests and tests that measure the oxygen level in your blood. The breathing tests most often used are:
These tests may not show what’s causing breathing problems. So, you may have other tests as well, such as a cardiopulmonary exercise test. This test measures how well your lungs and heart work while you exercise on a treadmill or bicycle.
Two tests that measure the oxygen level in your blood are pulse oximetry and arterial blood gas tests. These tests also are called blood oxygen tests.
Pulse oximetry measures the blood oxygen level using a special light. For an arterial blood gas test, your doctor inserts a needle into an artery, usually in your wrist, and takes a sample of blood. The oxygen level of the blood sample is measured.
Types of Pulmonary Function Test
Other Names for a Pulmonary Function Test
Who Requires a Pulmonary Function Test?
People who have breathing problems, such as shortness of breath, may need a pulmonary function test. These tests help find the cause of breathing problems.
Doctors use pulmonary function test to help diagnose conditions such as asthma, pulmonary fibrosis (scarring of the lung tissue), and COPD (chronic obstructive pulmonary disease).
Pulmonary function test also are used to check the extent of damage caused by conditions such as pulmonary fibrosis and sarcoidosis. Also, these tests may be used to check how well treatments, such as asthma medicines, are working.
Diagnosing Lung Conditions
Your doctor will diagnose a lung condition based on your medical and family histories, a physical exam, and test results.
What To Expect Before Pulmonary Function Test
If you take breathing medicines, your doctor may ask you to stop them for a short time before spirometry, lung volume measurement, or lung diffusion capacity tests.
What To Expect During Pulmonary Function Test
Spirometry may be done in your doctor’s office or in a special lung function laboratory (lab). Lung volume measurement and lung diffusion capacity tests are done in a special lab or clinic. For these tests, you sit in a chair next to a machine that measures your breathing. For spirometry, you sit or stand next to the machine.
Before the tests, a technician places soft clips on your nose. This allows you to breathe only through a tube that’s attached to the testing machine. The technician will tell you how to breathe into the tube. For example, you may be asked to breathe normally, slowly, or rapidly.
The deep breathing done in some of the tests may make you feel short of breath, dizzy, or light-headed, or it may make you cough.
For this test, you take a deep breath and then exhale as fast and as hard as you can into the tube. With spirometry, your doctor may give you a medicine that helps open your airways. Your doctor will want to see whether the medicine changes or improves the test results.
Lung Volume Measurement.
For this test, you sit in a clear glass booth and breathe through the tube attached to the testing machine. The changes in pressure inside the booth are measured to show how much air you can breathe into your lungs.
Sometimes you breathe in nitrogen or helium gas and then exhale. The gas that you breathe out is measured.
Lung Diffusion Capacity
During this test, you breathe in gas through the tube, hold your breath for 10 seconds, and then rapidly blow it out. The gas contains a small amount of carbon monoxide, which won’t harm you.
Tests To Measure Oxygen Level
Pulse oximetry is done in a doctor’s office or hospital. An arterial blood gas test is done in a lab or hospital.
For this test, a small sensor is attached to your finger or ear using a clip or flexible tape. The sensor is then attached to a cable that leads to a small machine called an oximeter. The oximeter shows the amount of oxygen in your blood. This test is painless and no needles are used.
What Does a Pulmonary Function Test Show?
Spirometry can show whether you have:
Lung Volume Measurement
This test shows the size of your lungs. Abnormal test results may show that you have pulmonary fibrosis or a stiff and/or weak chest wall.
Lung Diffusion Capacity
This test can show a problem with oxygen moving from your lungs into your bloodstream. This may be a sign of loss of lung tissue, emphysema (a type of COPD), or problems with blood flow through the body’s arteries.
Tests To Measure Oxygen Level
Pulse oximetry and arterial blood gas tests measure the oxygen level in your blood. These tests show how well your lungs are taking in oxygen and moving it into the bloodstream. A low level of oxygen in the blood may be a sign of a lung or heart disorder.