FEV1 / FVC ratio in spirometry: use, procedure, results


FEV1 / FVC is a ratio that reflects the amount of air you can forcefully exhale from your lungs. This relationship is often used in the diagnosis and follow-up of the treatment of lung diseases such as chronic obstructive pulmonary disease (COPD).

  • FEV1 , or forced expiratory volume in one second, is the forced expiratory volume during that period of time.
  • FVC, the forced vital capacity of the lungs, is the total amount of air that can be forcefully exhaled in one full inhalation.

Attitude is a more useful diagnostic tool than any measure taken separately.

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Purpose of the pulmonary function test

Once your healthcare provider determines that you have lung disease, they will often assess your FEV1 / FVC ratio to help determine the underlying type of disease you may have and, in particular, whether it is restrictive or obstructive in nature.

  • Restrictive lung diseases (such as pulmonary fibrosis) affect your ability to breathe.
  • Obstructive conditions (such as asthma and COPD) affect the ability to breathe out.

This test is often used to monitor lung disease, especially if you have an obstructive disease such as asthma. Regular measurement of the FEV1 / FVC ratio can help assess how well a treatment is working or how your condition is progressing.

FEV1 / FVC is just one of several measurements taken with a spirometer. The test can be done in your healthcare provider's office and takes about 45 minutes.

Risks and contraindications.

Spirometry is a very safe non-invasive test that involves breathing through a tube connected to a meter that measures airflow and force. Some people may feel dizzy or short of breath when blowing hard, or they may begin to cough.

If you have asthma, there is a small risk of an asthma attack during the test, and there is also a small risk that breathing with heavy effort may cause temporary but serious breathing problems. However, since the test is done under medical supervision, your doctor will be able to help you deal with any situation that may arise.


If you have one of the following conditions, a spirometry test is not recommended :

  • Recent chest pain, stroke, or heart attack
  • Lung collapse (pneumothorax)
  • Recent eye surgery or surgery to the chest or abdomen, as deep breathing can affect pressure in these areas.
  • An aneurysm (inflammation of a blood vessel) in the brain, chest, or abdomen.
  • Current or recent respiratory infection or tuberculosis

Interpretation of FEV1 / FVC results

Healthcare professionals can use a variety of tests to determine the severity of your condition. Spirometry is a test that helps assess lung function by measuring the force of your breathing.

By measuring FEV1 / FVC, spirometry records the amount of air you breathe out in one second, as well as the total amount of air you can breathe out. The ratio of these two values is expressed as a percentage. This is the percentage of FVC that has expired in one second.

Your test result is compared to a predicted value, which is a normal result based on your age, height, and gender. The normal ratio is 70 to 80% in adults and 85% in children.

FVC decreased with a proportional ratio of FEV1 / FVC

If your FVC is low, but your FEV1 / FVC ratio is normal, this indicates a restrictive nature.

Restrictive lung problems occur when a person cannot breathe as deeply as normal and are associated with damage to lung tissue.

Here are some examples:

  • Pulmonary fibrosis such as idiopathic pulmonary fibrosis , scarring of the lungs of unknown cause
  • Chest deformities such as scoliosis or scars on the chest.
  • Results of surgery for lung cancer , such as lobectomy or pneumonectomy.
  • Infections and inflammatory diseases such as pneumonia , tuberculosis , sarcoidosis , silicosis, and asbestosis.
  • Neurological disorders such as amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease)
  • Pleural effusion , in which fluid builds up in the area between the lungs and the chest wall.
  • Ascites, the accumulation of fluid in the abdomen due to liver disease or cancer, can cause a restrictive pattern, limiting the ability to breathe deeply.

Decreased FEV1 / FVC ratio

If you have a reduced FEV1 / FVC ratio, this is consistent with the pattern of obstruction.

This diagnosis is usually made if the FEV1 / FVC is less than or equal to 70% in adults and less than 85% in children.

Injury and / or narrowing of the airways indicates conditions such as:

  • Asthma
  • COPD, which includes chronic bronchitis, emphysema, and bronchiectasis.
  • Bronchiolitis

Severity assessment

If the FEV1 / FVC ratio deviates from the norm, the next step is to assess the deviation to determine the severity of the condition. The American Thoracic Society has developed specific guidelines for this purpose:

Abnormal FEV1 and FVC results
FEV1 / FVC ratio The severity of the condition
> 70% Less
60 to 69% Moderate
50 to 59% Moderately severe
35 to 49% Severe form
<34% Very heavy

Follow up

Your follow-up is determined by the test results, as well as your symptoms, medical history, and other diagnostic tests.

  • If a restrictive pattern is observed, healthcare professionals generally recommend more extensive lung function tests to further characterize your lung disease.
  • When an obstructive pattern is found, the next step is usually to recommend treatment with a bronchodilator , a drug that helps reduce the narrowing of the airways.

If you are being treated for obstructive pulmonary disease, your healthcare provider will likely monitor your progress by retesting your FEV1 / FVC ratio. If the ratio improves with a bronchodilator, this means that the obstruction is at least partially reversible. This is commonly seen in conditions like asthma. If the ratio does not improve with the use of bronchodilators, it may be irreversible, as is often the case in COPD.

Frequently asked questions

What percentage of FEV1 and FVC are normal in spirometric test results?

A ratio of 70% to 80% in adults and 85% in children is considered normal. Remember that your age, height, and gender are taken into account when determining what is normal for you.

Will exercise affect FEV1 and FVC levels?

Yes, exercise should have a positive effect. Research has shown that high intensity aerobic exercise performed regularly for weeks or months can improve lung function as measured by FEV1 and FVC levels. However, if you have a lung condition, always check with your doctor before starting an exercise program.

Will smoking affect my FEV1 and FVC levels?

Yes. Studies have shown that FEV1 and FVC levels worsen due to smoking, especially among people who have smoked for a longer period of time and / or smoked more cigarettes overall.

Get the word of drug information

The FEV1 / FVC ratio is just one of several tests that can help diagnose your specific lung condition. It's easy to get bogged down in a "good" or "bad" result, but this is only a small part of the information that is used to assess your condition. Your healthcare provider will also consider your general health, lifestyle, and other factors to carefully assess your condition and develop a treatment plan that is tailored to you.

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