WHAT IS SPIROMETRY
Spirometry is the most basic and frequently performed test of pulmonary (lung) function. A device called a
spirometer is used to measure how much air the lungs can hold and how well the respiratory system is able to
move air into and out of the lungs. Because spirometry is based on a maximal forced exhalation, the accuracy of its results are highly
dependent on the patient's understanding, cooperation, and best efforts.
Spirometry differs from peak flow readings in that spirometry records the entire forced breathing capacity against time, and peak flow
records the largest breathing flow that can be sustained for 10 milliseconds. Both are often used in asthma care.
WHY WOULD I NEED A SPIROMETRY TEST?
This test is used to determine the cause of shortness of breath, to rule out any kind of obstructive disease that blocks breathing, or
restrictive disease that limits the expansion and capacity of the lungs. Spirometry is most often used to diagnose and monitor lung
problems, such as chronic bronchitis, emphysema, pulmonary fibrosis, chronic obstructive pulmonary disease (COPD), or asthma.
Spirometry is also used to monitor how well medications for respiratory problems are working and to evaluate breathing capability prior
HOW IS SPIROMETRY PERFORMED?
A spirometry test is done with a spirometer, which consists of a mouthpiece with an air filter attached to a sensor and connected to a
computer. The system records the results, displays them on a graph and prints a summary report.
To perform spirometry, a person places the mouthpiece in their mouth, inhales deeply through their mouthpiece and then exhales
completely through the same mouthpiece. The air flowing through the sensor is measured and recorded. Some test measurements are
obtained by normal breathing, and other tests require rapid and forceful inhalation and/or exhalation. The volume of air inhaled or exhaled,
and the length of time each breath takes are recorded and analyzed.
Nose clips are usually used to make sure air is only coming out of the mouth. The test will be repeated to get the best and maximum
effort, usually requiring several attempts to attain two comparable quality recordings. Often, the tests are repeated again after a person
takes a medication that opens the airways of the lungs (a bronchodilator). A spirometry test can take anywhere from five to forty five
minutes, depending on the different types of breathing tests being measured and the variability of each effort.
Common parameters that spirometry measures are:
- Forced vital capacity (FVC) - The maximum volume of air, measured in liters that can be forcibly and rapidly exhaled.
- Forced expiratory volume (FEV1) - The volume of air expelled in the first second of a forced expiration.
ARE THERE RISKS ASSOCIATED WITH SPIROMETRY?
The risks are minimal for most people. Because the test involves forced and rapid breathing, some people may
experience temporary shortness of breath. Spirometry should not be done if a person suffers from chest pains, has
had a recent heart attack, or has serious heart disease.
Dizzyness may occur during the forced exhalation. Tell the person doing your test if you have low blood pressure or
easily become dizzy.
HOW SHOULD I PREPARE FOR SPIROMETRY?
- Do not eat a heavy meal before spirometry testing.
- Refrain from smoking for four to six hours before the test.
- Empty your bladder right before testing.
- Specific instructions are given if medications such as bronchodilators or inhalers need to be withheld before
- Sometimes, medication may be inhaled prior to the test, to test how well an individual responds to medication.