Forced Expiratory Volume in One Second or FEV1

Doctor explaining lung function test to young boy in clinic
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Do you know how strong your lungs are? Forced expiratory volume in one second, or FEV1, is a marker used to measure lung function and can help you monitor your chronic obstructive pulmonary disease (COPD) or other lung diseases over time. Here's what to know about FEV1, how's it's measured, and what it means for your COPD.

What Is FEV1?

FEV1 is the amount of air that can be forcibly exhaled from the lungs in the first second of a forced exhalation. It is one of the measures doctors use to determine your lung function. Because COPD causes the air in your lungs to be exhaled at a slower rate and in smaller amounts compared to a healthy person without COPD, measuring how well you can forcibly exhale air can help determine whether you have COPD or other lung diseases and also the severity of the disease.

FEV1 is but one of the pulmonary function tests which are done to evaluate lung function.

Measuring FEV1

In order to determine your FEV1, your doctor will conduct a spirometry test. During a spirometry test, you will be asked to blow into a tube. Measurements are then taken including that of how much air you can exhale forcefully in the first second of exhalation—your FEV1. Other tests are discussed below.

The result of your measurements will then be compared against "predicted" values—what normal readings would be expected in a person of similar age, gender, body size, and ethnicity, who do not have lung disease. This is done to standardize your reading and allows doctors to compare your test results to similar people with normal lung function.

Measurements are usually taken and then repeated after administration of a bronchodilator. A bronchodilator is a medication designed to open your airways. Looking at the difference in your lung function both with and without a bronchodilator allows your physician to evaluate how your treatment is working and if your COPD symptoms have improved.

Other Tests Measured Along With FEV1

As physicians generally look at a combination of different pulmonary function tests, it can be helpful to have a brief understanding of some of the other tests done along with an FEV1. These often include:

  • Vital capacity - Vital capacity is the maximum amount of air which can be inhaled or exhaled from the lungs.
  • Forced vital capacity (FVC) - Forced vital capacity is the maximum amount of air which can be exhaled from the lungs after taking the deepest breath possible.
  • Peak expiratory flow rate
  • Forced expiratory flow rate

What Do the Numbers Mean?

Your doctor will let you know the number of your FEV1 which is recorded as the percent of that predicted in someone with healthy lungs.

  • FEV1 from 80 to 100 percent is usually considered normal
  • FEV1 between 60 and 79 percent of predicted indicates a mild obstruction
  • FEV1 between 40 and 59 percent indicates a moderate obstruction
  • FEV 40 percent or less than predicted is considered severe obstruction

How to Improve FEV1

If your FEV1 is abnormal, your doctor will likely recommend a combination of therapies including both medications and lifestyle changes.

Medications to Increase FEV1

If your FEV1 is reduced, medications are often prescribed to improve your breathing. Both short-acting and long-acting bronchodilators are the mainstay of treatment. Medications include:

  • Beta-agonists can be used orally or by inhalation and include both short-acting and long-acting preparations.
  • Anticholinergics such as Spiriva are given by inhalation.
  • Methylxanthines such as theophylline are occasionally used.

There are also combination drugs which include a combination of these medications in order to reduce the number of medications you are required to take daily. Your doctor can help determine which of these drugs will work best for your particular symptoms and lung dysfunction.

Lifestyle Changes to Increase FEV1

Lifestyle factors, though often pushed to the back burner as we concentrate on medications, are extremely important in both managing the symptoms of COPD and slowing the progression of the disease.

  • Smoking cessation is by far the most important factor in improving FEV1 and slowing the progression of COPD.
  • Exercise is also beneficial for improving FEV1 and improving the symptoms of COPD. To get started, you can learn the best exercises for people with COPD.

Bottom Line on FEV1 in the Management of COPD

FEV1 and other pulmonary function tests can play an important role in the management of COPD. It's important to note, however, that it is more important to treat people than numbers. Some people tolerate a very low FEV1 whereas other people may be very symptomatic with only a mild reduction in FEV1.

One of the most important things you can do (other than quitting smoking if you smoke, of course) is to learn about your disease. Learn about the tests used to diagnose your disease and some of the factors which may influence the results. Take time to learn about your medications as well, both how they work and what the common side effects may be.

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