Lung Function Test (Spirometry)
Spirometry is a common lung function test that measures how much air you can breathe in and out and how quickly you can empty your lungs. You blow into a mouthpiece connected to a machine called a spirometer. The test is quick, painless, and uses no radiation, helping doctors assess and monitor breathing conditions.
Overview
What is a lung function test (spirometry)?
Spirometry is a breathing test that checks how well your lungs are working. You take a deep breath and blow out as hard and as long as you can into a tube attached to a spirometer. The machine measures the total amount of air you breathe out and how fast it comes out, giving doctors useful information about your airways.
Why is a lung function test (spirometry) done?
Spirometry helps diagnose and monitor breathing conditions such as asthma and chronic obstructive pulmonary disease (COPD). It is used to investigate symptoms like a long-lasting cough, breathlessness, or wheezing, to see how severe a known lung condition is, to check how well treatment is working, and sometimes to assess your lungs before surgery.
Test Details
How do I prepare for a lung function test (spirometry)?
Wear loose clothing that does not restrict your breathing, and avoid a heavy meal just beforehand. You may be asked to avoid smoking and strenuous exercise for a period before the test, and sometimes to pause certain inhalers so they do not affect the readings. Ask your care team which medicines to hold, and bring your inhalers with you.
What happens during a lung function test (spirometry)?
You sit comfortably and a soft clip is placed on your nose so all the air goes through your mouth. You seal your lips around the mouthpiece, breathe in fully, then blow out as hard and as long as you can. The test is repeated a few times for accuracy. Sometimes it is done again after an inhaler to see how your airways respond.
Results and Follow-Up
What happens after the test, and what do the results show?
You can return to your normal activities straight away; some people feel briefly light-headed from the deep breathing, which soon passes. Your measurements are compared with values expected for someone of your age, height, sex, and background. The results show whether your airways are narrowed or your lung capacity is reduced, and your doctor will explain what they mean and any next steps.
Additional Common Questions
Is spirometry uncomfortable?
The test is painless, though blowing out as hard as you can takes effort and may leave you briefly breathless or light-headed. Any such feeling settles within a few moments of finishing.
Why do I have to repeat the breathing several times?
Repeating the blow a few times helps ensure the results are accurate and consistent. Your care team uses the best efforts to get a reliable picture of how your lungs are working.
What is the inhaler sometimes used during the test for?
An inhaler may be given partway through to see whether your airways open up in response. Comparing the readings before and after helps doctors understand conditions such as asthma.
Sources
This health topic is for general information and is not a substitute for professional medical advice. Always consult a qualified clinician about your individual situation. See our medical disclaimer.