Forced vital capacity (FVC) is the amount of air that can be forcibly exhaled from your lungs after taking the deepest breath possible. It's measured by spirometry, which is a common breathing test to check lung function.
This test may help distinguish obstructive and restrictive lung diseases. Obstructive diseases, such as asthma and chronic obstructive pulmonary disease (COPD), make it difficult to exhale all the air from your lungs. Restrictive lung diseases, such as pulmonary fibrosis and sarcoidosis, cause problems with inhaling air to fill your lungs.
FVC can also help healthcare providers assess the progression of lung disease and evaluate the effectiveness of treatment. An abnormal FVC value may be chronic, but sometimes the problem is reversible and the FVC can be corrected.
This article discusses the purpose of the FVC test. It covers what to expect during the test and how results are interpreted.
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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.
While FVC cannot identify which specific lung disease you have, the results can help narrow down potential diagnoses. It can be used—along with other studies—to help determine which lung disease you have.
Reasons you may need to have your FVC measured include:
- You have shortness of breath, a persistentcough, or wheezing.
- Your healthcare provider wants to assess your respiratory function when your blood oxygen level is low.
- You’re having surgery. It’s important to know if breathing is stable prior to a procedure, especially if you will be having lung surgery.
- You have heart disease and need an assessment of its effects on your ability to breathe.
- You and your healthcare provider are planning your lung rehabilitation program.
- You’ve reached the endpoint in a clinical trial expected to affect lung function.
Associated Tests
You may have other tests done when you go in to have your FVC measured. These include your vital capacity (VC) and forced expiratory volume over one second (FEV1).
FVC and VC record similar information. They both measure the amount of air you can exhale after maximally inhaling. But FVC refers to the amount of air you can exhale forcefully. VC records the maximum amount of air exhaled when breathing normally.
FEV1 differs in that it measures the amount of air you can exhale in one second.
Your FVC and other pulmonary 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.
Recap
An FVC test measures the amount of air you can exhale forcefully after taking a deep breath. When used with other lung tests, it can help your doctor diagnose what kind of lung condition you have.
Risks and Contraindications
FVC requires your cooperation and effort, but it is safe. However, be sure to have medical supervision the first time you use a spirometer, the device used to measure your FVC. You could potentially use a spirometer the wrong way, exhausting yourself.
Afterward, you may be instructed on how to use it at home 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.
If a friend or family member uses home spirometry, don't use their device to measure your FVC or for other pulmonary function tests.
Before the Test
Before your FVC test, your healthcare provider may give you instructions regarding your medication. You may also be directed to use your inhaler (or another treatment) so your medical team can assess how well it is working.
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.
There are other aspects to pulmonary testing, such as functional residual capacity (FRC), which measures air in your lungs after exhaling. You may need other tests if your pulmonary condition has been difficult to diagnose or if you are not improving as expected.
Your whole battery of tests could take an hour or longer.
Location
You will have your FVC test in your healthcare provider’s office or at a pulmonary testing laboratory.
What to Wear
Be sure to wear loose clothing so that you will not feel restricted when you are breathing. It is important that you can inhale and exhale as deeply as you can during the test.
Food and Drink
You will not have to make any adjustments to your food and drink prior to or after having an FVC 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. Be sure to check with your insurer to ask whether you will have to pay a co-pay or the whole cost of the test.
Keep in mind that if you are having other pulmonary tests, your total cost will be higher.
What to Bring
Bring a list of all of your medications, a form of identification, your health insurance information, and a form of payment.
Also, bring your inhalers with you, even if you have been instructed not to use them prior to your test. You may be asked to use your inhaler during your test.
Recap
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.
During the Test
When you arrive for your test, you will be asked to sign in and provide your paperwork. 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.
FVC spirometry is performed as follows:
- You are seated in a chair and asked to breathe comfortably.
- A clip is placed over your nose.
- You are given a tube to breathe into.
- Sealing your lips tightly over the tube, you are asked to inhale as deeply as possible. You then exhale as forcefully as you can.
The procedure is repeated at least three times to obtain a consistent and average value.
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 have severe lung disease, that support may include supplemental oxygen or caregivers to help you get around.
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.
Additionally, if you are having persistent or serious symptoms, you might need to have your oxygen level checked. If it is low, you will be given supplemental oxygen.
Recap
During the test, you'll be given a tube to breathe into, inhaling deeply and then exhaling forcefully. You'll probably have to repeat it three times so they can get an average measurement. If you feel dizzy or short of breath, you may be asked to sit for a few minutes to recover.
Interpreting Results
Your total FVC volume can be compared with the standard FVC for your age, sex, height, and weight. 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:
- As an absolute value, reported as a number in liters (L)
- On a linear graph to chart the dynamics of your exhalation
The normal FVC range for an adult is between 3.0 and 5.0 L.
For children, the expected FVC can be predicted using reference tables that incorporate the child’s height, body weight, and other factors. For example, the standard FVC for an average-size preschool boy is 1.16 L, and 1.04 L for an average-size preschool girl.
FVC also may be expressed as a percentage of the predicted FVC.
Diminished FVC
Forced vital capacity can be decreased temporarily or permanently. A diminished FVC value is a sign of several conditions, including:
- Chronic obstructive pulmonary disease (COPD), including chronic bronchitis, emphysema, and bronchiectasis
- Restrictive airway diseases, such as idiopathic pulmonary fibrosis
- Structural restrictive airway diseases, such as those produced by scoliosis and chest scarring
- Diseases such as sarcoidosis
- Inflammatory lung diseases, such as asbestosis and silicosis
- Lung cancer
FEV1/FVC Ratio
Your FVC value may be used to calculate your FEV1/FVC ratio. The ratio of FEV1 to FVC compares the amount of air that can be forcefully expelled in one second to the amount that can be expelled in total. A normal FEV1/FVC ratio is 70% to 80% or higher in adults and 85% or higher in children.
The FEV1/FVC ratio can help identify whether a pulmonary condition is obstructive (such as with COPD) or restrictive (such as with pulmonary fibrosis). Any change in the FEV1/FVC ratio can provide valuable information as to whether lung obstruction and/or lung restriction is occurring.
While restrictive diseases limit air intake, they do not inherently affect the force of your exhalations. By contrast, obstructive diseases can make it difficult to exhale, but they don’t necessarily alter the volume of your airways.
With Restrictive Diseases
FEV1 and FVC will both be decreased proportionally, so that the ratio of FEV1/FVC is equivalent.
With Obstructive Diseases
The FEV1/FVC ratio will be less than 70%.
If both the FEV1/FVC ratio and FVC are low, the individual has a mixed defect with both restriction and obstruction.
Follow-Up
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. You may need to have full pulmonary function tests and imaging tests, such as a chest/lung computerized tomography (CT).
If the FEV1/FVC ratio is low, it suggests obstructive lung disease. Your healthcare provider may repeat the test with a bronchodilator to 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.
Recap
Follow-up tests may include pulmonary function tests, a chest/lung CT scan, or bronchodilator tests. These can help to narrow down what type of obstructive or restrictive lung condition you have.
Summary
An FVC test helps evaluate your lung function. It measures how much air you can forcibly exhale after taking a deep breath. This helps determine whether you have an obstructive lung condition, which makes it hard to exhale, or a restrictive condition, which makes it hard to inhale.
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 can. 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.
A Word From Verywell
While FVC is a valuable measurement in evaluating lung disease, it is important to remember that it is just a number. Your healthcare provider will look at your medical condition, your general health, and other findings. That will help them understand how your FVC measurement fits into the big picture of your health.
FAQs
What is FVC forced vital capacity? ›
Forced vital capacity (FVC) is the total amount of air exhaled during the FEV test. Forced expiratory volume and forced vital capacity are lung function tests that are measured during spirometry. Forced expiratory volume is the most important measurement of lung function.
What FVC value indicates a lung problem? ›The FEV1 is used with the FVC to differentiate between obstructive lung disease (FEV1/FVC < 70%) and restrictive lung disease (reduced FEV1 and FVC but normal FEV1/FVC relationship). An FEV1 of less than 1 L indicates significant lung disease.
How do you check FEV1 FVC? ›FEV1 is the amount of air you can force from your lungs in one second. It's measured during a spirometry test, also known as a pulmonary function test, which involves forcefully breathing out into a mouthpiece connected to a spirometer machine.
What is FVC and how is it measured? ›What Is Forced Vital Capacity (FVC)? Spirometry tests / pulmonary function tests can be used to measure a patient's forced vital capacity or FVC, which is the amount of air that an individual is able to forcibly exhale from his / her lungs after taking the deepest breath they can.
What happens if FVC is low? ›A normal FEV1/FVC ratio with a decreased FVC indicates a restrictive lung condition. These can include pulmonary fibrosis and infections like pneumonia. A decreased FEV1/FVC ratio indicates an obstructive condition, such as asthma or COPD.
What should my forced vital capacity be? ›Forced vital capacity: the maximum amount of air you can forcibly exhale from your lungs after fully inhaling. It is about 80 percent of total capacity, or 4.8 liters, because some air remains in your lungs after you exhale.
How do you fail a pulmonary function test? ›There's no such thing as failing a PFT. If it's abnormal, your provider will discuss additional work you may need to obtain a diagnosis and a treatment plan.
What is an abnormal FVC? ›A diminished FVC value is a sign of several conditions, including: Chronic obstructive pulmonary disease (COPD), including chronic bronchitis, emphysema, and bronchiectasis. Restrictive airway diseases, such as idiopathic pulmonary fibrosis.
How do you fail a spirometry test? ›Spirometry is a test of maximal effort, therefore, a slight hesitation or a delayed start can affect results, and so is one of the common mistakes when performing Spirometry. A hesitation in blowing out before the initial blast affects most spirometry test results early in the manoeuvre.
Does Medicare cover pulmonary function test? ›Medicare does not cover screening tests.
Medicare coverage excludes routine (screening) tests for asymptomatic patients with or without high risk of lung disease (e.g., prolonged smoking history).
How much does spirometry test cost? ›
PFT or Spirometry test cost ranges from Rs 750 to Rs 1000 in India.
What FEV1 FVC indicates asthma? ›The Global Initiative for Asthma (GINA) defines asthma by combining variable respiratory symptoms with variable expiratory airflow limitation, expressed as an FEV1/FVC ratio less than 75-80% (7).
What not to do before a pulmonary function test? ›Do not eat, smoke, or exercise 4-8 hours before testing. Wear loose-fitting clothing.
When is a pulmonary function test required? ›Testing may be performed on workers who perform jobs that may cause exposure to possible lung hazards, are physically demanding, or require wearing a respirator. The test shows how well you can move air in and out of your lungs. Spirometry testing is required for some workers by OSHA standards.
Is FVC the same as lung capacity? ›Vital capacity, simply measured by spirometry, is a lung volume measurement that can be measured as slow vital capacity (VC) or forced vital capacity (FVC). There is little or no difference between VC and FVC (VC-FVC) in normal subjects [11].
Does weight Affect FVC? ›The effect of weight gain on pulmonary function was greater in men than in women. Multiple regression analysis showed that each kilogram of weight gain was associated with an excess loss of 26 ml in FVC and 23 ml in FEV1 in men, and 14 ml and 9 ml respectively in women.
Does FVC decrease with age? ›All included studies demonstrated decline in lung function—forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and peak expiratory flow rate (PEFR) with age.
What is the most common cause of a falsely low FVC? ›Significant coughing may cause a falsely reduced FVC. In any case, because the FEV1/FVC ratio may be inaccurate, the maneuver is unacceptable.
Does body size affect FVC? ›In contrast to weight gain, obese (but not overweight or normal BMI) adults at baseline who lost weight during follow-up exhibited an attenuation of FVC decline (panel C in figure 1). We estimated that, at age 25 years, obese participants had lower FVC levels than normal BMI participants.
Is an FVC of 1.78 normal? ›Forced Vital Capacity (FVC)
The volume is measured in liters. Average normal values for healthy males age 20-60 range from 4.75 to 5.5 liters. For females age 20-60, the normal range is from 3.25 to 3.75 liters.
Can lung function be restored? ›
The lungs' large surface area exposes the organ to a continual risk of damage from pathogens, toxins or irritants; however, lung damage can be rapidly healed via regenerative processes that restore its structure and function.
What are 3 diseases that may affect pulmonary function test? ›Respiratory infections. Trouble breathing from injury to the chest or a recent surgery. Chronic lung conditions, such as asthma, bronchiectasis, emphysema, or chronic bronchitis. Asbestosis, a lung disease caused by inhaling asbestos fibers.
Why can't I drink coffee before a pulmonary function test? ›Avoid food or drinks with caffeine. Caffeine can cause your airways to relax and allow more air than usual to pass through. If you have dentures, wear them during the test, if they fit comfortably. They help you form a tight seal around the mouthpiece of the machine.
How does caffeine affect a pulmonary function test? ›Caffeine can also affect the pulmonary function test by causing the airways to be more open than they would normally. Patients should avoid caffeine as well as smoking for several hours before their appointment.
What are the 4 factors that affect lung capacity? ›Age, gender, body composition, and ethnicity are factors affecting the different ranges of lung capacity among individuals. TLC rapid increases from birth to adolescence and plateaus at around 25 years old.
Is FVC normal in restrictive lung disease? ›In the restricted lung, the FVC is again smaller than normal, but the FEV1 is relatively large in comparison. i.e. the FEV1/FVC ratio can be higher than normal, for example 90% as opposed to 80%.
What are 5 factors that affect lung capacity? ›Physiological factors that influence lung volumes/capacities include age, gender, weight, height and ethnicity, physical activity, altitude and others, which should be considered while interpreting results of spirometry.
Who shouldn't take a spirometry test? ›Other contraindications for spirometry include coughing up blood (hemoptysis) without a known cause, active tuberculosis, and a history of syncope associated with forced exhalation. Individuals with a history or increased risk of pneumothorax should also avoid spirometry testing.
How can I improve my lung spirometry? ›Regular exercise, eating a healthy diet, and avoiding tobacco smoke can all help keep your lungs functioning at their best. If you're experiencing symptoms of low lung capacity, such as shortness of breath, it's important to see a doctor to find out if an underlying condition is causing them.
How can I strengthen my lungs? ›Both aerobic activities and muscle-strengthening activities can benefit your lungs. Aerobic activities like walking, running or jumping rope give your heart and lungs the kind of workout they need to function efficiently.
What does FEV1 FVC 70% mean? ›
This is a measure of how quickly the lungs can be emptied. • FEV1/FVC: FEV1 expressed as a percentage of the FVC, gives a clinically. useful index of airflow limitation. The ratio FEV1/FVC is between 70% and 80% in normal adults; a value less than 70% indicates airflow limitation and the possibility of COPD.
What is FEV1 vs FEV1 FVC? ›Forced expiratory volume (FEV) measures how much air a person can exhale during a forced breath. The amount of air exhaled may be measured during the first (FEV1), second (FEV2), and/or third seconds (FEV3) of the forced breath. Forced vital capacity (FVC) is the total amount of air exhaled during the FEV test.
Is vital capacity the same as FVC? ›Vital capacity, simply measured by spirometry, is a lung volume measurement that can be measured as slow vital capacity (VC) or forced vital capacity (FVC). There is little or no difference between VC and FVC (VC-FVC) in normal subjects [11].
What is the GOLD criteria for COPD? ›Using GOLD criteria
The main criterion for COPD is a FEV1/FVC ratio <70%. Subclassification into mild, moderate, severe and very severe disease is achieved by including various levels of FEV1 as percentage of predicted value 2.
Abnormal results usually mean that you may have chest or lung disease. Some lung diseases (such as emphysema, asthma, chronic bronchitis, and infections) can make the lungs contain too much air and take longer to empty.
What are examples of restrictive lung disease? ›Examples of restrictive lung diseases include asbestosis, sarcoidosis and pulmonary fibrosis.
How can you tell the difference between asthma and COPD on spirometry? ›Commonly used spirometry measurements of relevance for the differentiation of asthma from COPD include the volume of air that can be forcibly exhaled in a single breath after a maximum inspiration (forced vital capacity [FVC]), the FEV1 of this maneuver, and the ratio of these measurements (FEV1/FVC).
Does spirometry measure forced vital capacity? ›Results. Key spirometry measurements include the following: Forced vital capacity (FVC). This is the largest amount of air that you can forcefully exhale after breathing in as deeply as you can.