Spirometry

What Is Spirometry?

When you’re having trouble breathing, your doctor might order a test called spirometry. Spirometry is a very common test to see how well your lungs work. Spirometry measures three things:

  1. How much air you can breathe in (inhale)
  2. How much air you can breathe out (exhale)
  3. How fast you can exhale the air from your lungs

Conditions That Spirometry Can Diagnose

Your doctor will look at your test results to figure out what may be making it hard to breathe. Common causes include:

  • Asthma
  • Chronic obstructive pulmonary disease (COPD)
  • Cystic fibrosis
  • Scars in your lungs (pulmonary fibrosis)

How to Prepare for the Spirometry Test

You don’t need to do anything to prepare for spirometry, though there are a few things to keep in mind:

  • Don’t eat a big meal right before the test.
  • Ask your doctor if there are medications you should not take the day of the test.
  • Wear comfortable clothes.

The test itself takes about 15 minutes. It’s done in your doctor’s office, and afterward, you can go about your day as normal.

How Spirometry Works

You’ll sit in a chair and have a clip placed on your nose to keep your nostrils closed. Then, you’ll take a deep breath and exhale as quickly and hard as you can into a tube.

You’ll need to wrap your lips tightly around the tube so all your air goes into it. Usually, the test is given three times to make sure the results are the same every time.

The tube connects to a machine called a spirometer. It records how much air you breathe out from your lungs and the speed at which you exhale.

All this information helps the doctor figure out what’s causing your breathing problems.

Spirometry Test Risks

Spirometry is a painless test. Most people have no problems with it. Depending on your health, the deep breathing might make you feel a little tired or lightheaded.

If you have heart disease or have had surgery recently, check with your doctor to make sure spirometry won’t be a problem for you.

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Spirometry Test Results

You might hear your doctor or a technician refer to two key measurements in spirometry. They are:

  • Forced vital capacity (FVC). This measures the amount of air you can breathe in and out.
  • Forced expiratory volume (FEV-1). This measures how much air you can exhale from your lungs in 1 second.

A doctor will look at your age, height, and gender to figure out whether your results are in the normal range. Numbers outside this range can suggest a lung problem.

 Your doctor should get a report within a few days and talk it over with you.

If the doctor thinks your airways are blocked, they may give you a medication that opens them up. It’s called a bronchodilator. After several minutes, you may take the spirometry test again to see whether the bronchodilator made a difference.

A low FEV-1 score suggests you have an obstructive airway disease such as COPD. This means your lungs can fill with air normally, but your airways are too narrow to exhale as much as they should.

If your lungs can’t fill enough, you have a restrictive lung disease.

There are several types of these conditions, but one of the most common is pulmonary fibrosis. If you have this disease, some of the tissue in your lungs has become scarred. It won’t expand when you inhale, so you can never get quite enough breath.

Do I Need Spirometry?

This is one of the most important tests for a doctor to diagnose lung disease.

If you’re having any breathing problems, talk about spirometry with your doctor. If there's a chance you might have COPD, asthma, or some other lung condition, this test is a good first step toward getting a diagnosis.

Spirometry is also helpful in testing how well a bronchodilator or other treatment is working. You may have had spirometry testing when you were first diagnosed with asthma. A test after you’ve been taking asthma medications for a while can let you and your doctor know whether you’re on the right treatment track.

WebMD Medical Reference Reviewed by Minesh Khatri, MD on September 25, 2019

Sources

SOURCES:

Mayo Clinic: “Spirometry: Definition,” “Spirometry: What can you expect,” “Spirometry: Why it’s done.”

National Health Service: “Spirometry.”

Lung Institute: “What is pulmonary fibrosis?”

Asthma and Respiratory Foundation of New Zealand: “What is Spirometry?”

American Lung Association: “Spirometry.”

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