Spirometry – Normal Values and Test Results

What is spirometry?

For a spirometry test, we sit and breathe in a little machine called a spirometer. This medical device measures how much air you inhale or exhale and how quickly you breathe.

Spirometry is a standard lung functional test Doctors use to measure your lungs working properly. This test measures how much air is inhaled and exhaled in your lungs.

Spirometry tests are performed for these conditions:

  • COPD
  • emphysema
  • asthma
  • bronchitis
  • restrictive lung disease (such as interstitial pulmonary fibrosis)
  • other diseases affecting lung function.

They also make it possible for your doctor to examine chronic lung diseases to check that Your present treatment improves your breathing.

Spirometry is typically performed in a group of tests known as lung function tests.

How to prepare for a spirometry test

You’re not supposed to smoke an hour before a spirometry test. You should also prevent alcohol that day. Eating too much food may also affect your capacity to breathe.

Do not wear tightly fitting clothing that may prevent you from breathing. Your doctor may also tell you if you should avoid inhaled respirators or other medications before your test.

Spirometry procedure

A spirometry test often takes approximately 15 minutes and is usually carried out in your doctor’s office. The spirometry test is performed using the following method:

  1. You will sit in a chair in an examination room at the clinic of your doctor. Your doctor or nurse uses pliers to close your nostrils. They also put a teacup-shaped respirator around your mouth.
  2. Your doctor or nurse then tells you to breathe deeply, hold your breath for a couple of seconds, and Then breathe out with great force in the breathing mask.
  3. You will do this test at least three times to ensure the results are stable. Your physician or nurse may ask you to repeat the test several times if there is a large difference in your results. They will take the highest value of three tests together and use it as the end result.

If there’s evidence of a respiratory problem, your doctor could then give you an inhaled medicine called a bronchodilator to open your lungs after the first set of tests. After that, they will ask you to wait 15 minutes before taking another test. Next, your doctor will compare the results of both measures to see if the bronchodilator has helped to increase your airflow.

When used for monitoring breathing problems, a A spirometry test is usually performed once a year every two years to examine changes in respiration in individuals with well-controlled COPD or asthma. It is suggested that people who have more severe breathing problems or breathing problems that are not well managed undergo repeated spirometry tests.

Adverse effects of spirometry.

Not many complications can occur during or after a spirometry test. You may experience little dizziness or shortness of breath (shortness of breath) immediately after completing the test. Very rarely, the test can cause serious respiratory problems.

The test requires some effort, so it is not recommended if you have recently had heart disease or other cardiac complications.

Spirometry normal values and how to read your test results

The normal results of a spirometry test are different between people. It depends on your age, size, race and gender. Your physician will calculate the normal value for you before taking the exam. Once you have finished the test, they will look at your result and compare it to the expected value. Your result is considered normal if your score is equal to or greater than 80 percent of its expected value.

You can obtain a normal estimate of your expected normal value using a spirometry calculator. The Centers for Disease Control and Prevention (CDC) provides a calculator which allows you to enter your personal information. If you know your spirometry results before, you can input them as well, and the calculator will tell you what percentage of the expected values your results are.

Spirometry has two primary factors:

expiratory forced vital capacity (FVC) and forced expiratory volume in one second (FEV1).

Your physician will also look at these as a combined number called the FEV1/FVC ratio. If you have blocked the respiratory tract, the amount of air you are able to exhale rapidly out of your lungs will be reduced. The result is a lower FEV1 and FEV1/FVC ratio.

FVC measurement

A basic measurement of spirometry is FVC, that is the greatest total amount of air you can force out after breathing as deep as you can. If your FVC is below normal, there is something that restricts or restricts your breathing.

Both normal and abnormal outcomes are evaluated differently for adults and children:

For children between the ages of 5 and 18:

If the percentage of the expected FVC value is 80% or higher, the result is normal and if it is below 80%, the result is abnormal.

For adults: FVC The result is greater than or equal to the lower limit of the normal therefore the result is normal, if the limit is under the normal limit, the result is abnormal.

Abnormal FVC may be caused by restricted or obstructive pulmonary disease, and other kinds of spirometric measurements are needed to determine what kind of pulmonary disease is present. Obstructive or restrictive pulmonary disease may occur on its own, but it is possible to have these two types at the same time.

FEV1 measurement

The second most common spirometry measure is forced expiratory volume (FEV1). That’s how much air you can squeeze out of your lungs in one second. This may help your doctor determine the severity of your respiratory complications. A lower than normal FEV1 reading shows that you may have a noticeable obstruction or blocking of breathing.

Your physician will use your FEV1 measure to assess the severity of any abnormalities. The table below describes what is considered normal and abnormal for your FEV1 spirometry results, as per the guidelines of the American Thoracic Society:

Percentage of predicted FEV1 value :

  • 80% or more – normal
  • 70%–79% – mildly abnormal
  • 60%–69% – moderately abnormal
  • 50%–59% – moderate to severely abnormal
  • 35%–49% – severely abnormal
  • Less than 35% – very severely abnormal

FEV1/FVC ratio

Physicians normally examine the FVC and FEV1 separately, and then calculate your FEV1/FVC ratio. The FEV1/FVC ratio is a number that is the percentage of pulmonary capacity that you can exhale within a second.

The larger the percentage you get from your FEV1/FVC ratio, in the lack of restrictive pulmonary disease that causes normal or increased FEV1/FVC, the well-being of your lungs. A low report rec5 to 18 years of age :ommends something to block or obstruct your airway:

5 to 18 years of age :

  • low FEV1/FVC ratio – less than 85%

Adults :

  • low FEV1/FVC ratio – less than 70%

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