It’s measured byspirometry, which is a common breathing test to check lung function.
This test may help distinguishobstructive and restrictive lung diseases.
Restrictive lung diseases, such as pulmonary fibrosis andsarcoidosis, cause problems with inhaling air to fill your lungs.
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FVC can also help healthcare providers assess the progression of lung disease and evaluate the effectiveness of treatment.
This article discusses the purpose of the FVC test.
It covers what to expect during the test and how results are interpreted.
Purpose of FVC
FVC is used to evaluate your lung function.
It measures the effect that your lung disease has on your ability to inhale and exhale.
It can be usedalong with other studiesto help determine which lung disease you have.
These include yourvital capacity (VC)andforced expiratory volume over one second (FEV1).
FVC and VC record similar information.
They both measure the amount of air you’re free to exhale after maximally inhaling.
But FVC refers to the amount of air you’re able to exhale forcefully.
VC records the maximum amount of air exhaled when breathing normally.
FEV1 differs in that it measures the amount of air you’re able to exhale in one second.
Your FVC and otherpulmonary function tests (PFTs)are used to establish the status of your lung function.
They compare your measurements to standards based on your age, gender, race, height, and weight.
Risks and Contraindications
FVC requires your cooperation and effort, but it is safe.
You could potentially use a spirometer the wrong way, exhausting yourself.
Afterward, you may be instructed on how to use it athome on your own.
You should be sure the spirometer you use has been adequately cleaned before each use.
That way you won’t be exposed to anything that can cause an infection.
A lung infection or exposure to cigarette smoke can affect your results, too.
It’s important that you discuss these issues with your healthcare provider before having your test.
If needed, your FVC may be rescheduled.
Timing
The FVC test itself should only take a few minutes.
Be sure to ask your medical team how long you should expect to spend at the testing site.
Your whole battery of tests could take an hour or longer.
It is important that you could inhale and exhale as deeply as you could during the test.
Cost and Health Insurance
The price of this test can range between $40 and $80.
If you have health insurance, your carrier may cover all or part of that cost.
Keep in mind that if you are having other pulmonary tests, your total cost will be higher.
You may be asked to use your inhalerduringyour test.
Your healthcare provider will let you know if you should use your inhaler or other medicine before the test.
The FVC test will likely take just a few minutes.
It’s usually done in your healthcare provider’s office or a pulmonary testing laboratory.
You will meet a medical team, which may include a technician, nurse, and/or doctor.
Throughout the Test
Spirometry is non-invasive and only takes a few minutes.
Other pulmonary function tests will likely be performed at this same appointment.
Post-Test
You will most likely not need any recovery time after you have completed your FVC test.
You will typically need the same care and support after the test that you usually need.
If you feel dizzy or short of breath, be sure to tell your medical team.
You may be asked to sit for a few minutes as you recover.
If it is low, you will be given supplemental oxygen.
You’ll probably have to repeat it three times so they can get an average measurement.
Your FVC can also be compared with your own previous FVC values.
This can determine whether your pulmonary condition is progressing or if your lung function is improving under treatment.
Forced vital capacity will be reported in two ways:
What Is the FVC Normal Range?
FVC also may be expressed as a percentage of the predicted FVC.
What Does a Low FVC Mean?
Forced vital capacity can be decreased temporarily or permanently.
While restrictive diseases limit air intake, they do not inherently affect the force of your exhalations.
FEV1 and FVC will both be decreased proportionally, so that the ratio of FEV1/FVC is equivalent.
The FEV1/FVC ratio will be less than 70%.
You may need to have further testing after your FVC is done or after your FVC/FEV1 ratio is calculated.
For example, respiratory symptoms with a normal FEV1/FVC ratio suggest a restrictive pattern.
If the FEV1/FVC ratio is low, it suggests obstructive lung disease.
Your healthcare provider may repeat the test with abronchodilatorto see if the obstruction is reversible.
An obstructive condition such as asthma tends to be reversible, whereas a condition like COPD is not.
Once you are diagnosed with a lung disease that affects FVC, you may need this test repeated periodically.
That way your medical team can continue to monitor your condition.
Summary
An FVC test helps evaluate your lung function.
It measures how much air you’re free to forcibly exhale after taking a deep breath.
When you take the test, your doctor will ask you to breathe into a tube.
You’ll take a deep breath and then blow out as forcefully as you might.
You may be asked to bring your inhaler to your appointment to see how it affects your lung function.
Afterward, your healthcare provider may request follow-up tests, such as imaging, to help diagnose your condition.
It can provide a useful baseline for comparison should lung problems develop in the future.
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