What is spirometry?
Spirometry is a type of pulmonary function test, or a lung function test, that measures the flow of air through your lungs. It also estimates the amount of air in your lungs. The test is performed using a machine called a spirometer. It measures the amount of air you breathe and how fast you can blow air out of your lungs. Spirometry is a safe and commonly ordered test.
Why is spirometry done?
Spirometry tests determine if lungs are functioning at expected levels. It helps to diagnose lung and airway diseases. For example, the test can detect chronic obstructive pulmonary disease (COPD) before symptoms develop. The test can also check for pulmonary fibrosis, or scarring of the lung tissue.
Other reasons why spirometry is done:
- To determine lung capacity
- To measure the changes over time of chronic diseases on lung function
- To identify early changes in lung function and in some cases to help guide treatment
- To detect narrowing in the airways
- To decide how likely it is that inhaled medicines may help with symptoms
- To show whether exposure to substances has altered lung function
- To estimate your risk of respiratory complications before undergoing surgery
How do I prepare for spirometry?
Before you take the test, the doctor may ask you to:
- Not take your breathing medicines for a short time
- Wear loose-fitting clothing for the test
- Not eat a large meal 2 hours before
- Not do any heavy exercising 30 minutes before the test.
These will help you breathe into the tube more comfortably and make your results more accurate.
What should I expect during spirometry?
Spirometry can be done in the doctor’s office or a special lung function laboratory. You can expect to go through the following during spirometry:
- Soft clips will be placed on your nose. This helps you breathe out only through the tube attached to the spirometer.
- You will be asked to take a deep breath in.
- Then, you will blow into a tube connected to the spirometer. You will be asked to blow as hard and fast as you can.
- You may also be asked to breathe in a medicine that helps to open your airways followed by blowing out into the tube again.
- The doctor will see the test results before and after you inhaled the medicine and determine whether you may benefit from treatment with it.
You feel no pain during the test. The test is repeated three times to make sure the results are reproducible and accurate. It usually takes up to 30 minutes to complete the test. You might feel lightheaded or tired due to the effort of breathing in and out so deeply. You may also cough as a result of blowing into the tube. Those symptoms should quickly resolve after completing the test.
Results and Follow-Up
What should I expect after spirometry?
After the test, you can restart any medicines that your doctor told you to stop taking. You can also return to normal activities. Your doctor will advise you as to when the results will be ready to discuss.
What do the test results mean?
Spirometry can help doctors determine:
- If the patient’s symptoms are caused by asthma or another process
- If there is a blockage or narrowing in the airways
- If treatment is working
- If a disease is stable or getting worse
- Level of severity of the disease
- If lungs are lower in volume than normal which may warrant additional testing
What follow-up is necessary?
The doctor will review the test results with you. At that time, the doctor will set treatment goals and a long-term plan based on the results of the spirometer.