Medically Reviewed By William C. Lloyd III, MD, FACS
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What is spirometry?

Spirometry is a simple, painless test that measures lung constriction and the speed of exhalation. Spirometry involves blowing into a mouthpiece while a spirometer records measurements on a graph. Doctors use spirometry to diagnose and manage diseases that affect breathing, such as asthma and COPD (chronic obstructive pulmonary disease). 

Spirometry is only one method of diagnosing and managing respiratory diseases. Discuss all your monitoring and testing options with your doctor to understand which options are right for you.

Other procedures that may be performed

Spirometry is a type of pulmonary or lung function test. Your doctor will likely recommend one or more other pulmonary function tests to diagnose and monitor your respiratory disease. Pulmonary function tests include:

  • Arterial blood gas test to measure oxygen and carbon dioxide levels and other factors in the blood

  • Body plethysmography to determine how much air is present in your lungs when you take a deep breath and how much air is left in your lungs after you exhale as much as you can. Spirometry can be done at the same time as a body plethysmography using the same equipment.

  • Bronchoprovocation tests to measure lung function after exposure to factors that commonly trigger asthma. This includes a methacholine challenge test to help diagnose asthma.

  • Lung diffusion capacity to measure how well oxygen moves into your blood from your lungs

  • Peak expiratory flow to measure the speed of exhaling and lung constriction. People with asthma often use this test routinely to monitor their asthma control.

  • Pulse oximetry to measure oxygen levels in the blood

Why is spirometry used? 

Your doctor may recommend spirometry to diagnose and determine the severity of diseases that affect breathing. It is also used to determine how well treatments are working. Diseases include:

  • Asthma is a chronic lung disease marked by acute flare-ups of inflammation and swelling of the airways in the lungs.

  • Acute bronchitis is lung inflammation generally due to an infection of the bronchial tubes in the lungs.

  • Cardiac diseases include congestive heart failure, congenital (present at birth) heart disease, and pulmonary hypertension.

  • COPD (chronic obstructive pulmonary disease) includes emphysema and chronic bronchitis.

  • Cystic fibrosis is a genetic disorder that causes thick, sticky mucus buildup in the lungs and other organs.

  • Neuromuscular diseases include multiple sclerosis, myasthenia gravis, and Guillain-Barré syndrome.

  • Pneumonia is inflammation of the lungs, usually due to a viral or bacterial infection.

  • Pulmonary fibrosis is lung scarring due to the growth of excessive fibrous tissue in the lungs.

Your doctor may also use spirometry in the following situations: 

  • You are a current or former smoker.

  • You are having surgery including abdominal, heart or lung surgery.

  • You have abnormal test results including abnormal arterial blood gases and chest X-ray.

  • You have symptoms of respiratory disease including chest tightness, cough, phlegm, wheezing, and shortness of breath.

Who performs spirometry?

A pulmonary function technologist, or specially trained respiratory therapist or nurse performs spirometry. A pulmonary function technologist is a healthcare provider who specializes in performing lung function tests to diagnose and treat lung diseases, including asthma, COPD (chronic obstructive pulmonary disease), and other breathing problems. 

The following types of doctors order and supervise spirometry testing:

  • Allergist-immunologists specialize in caring for people with allergies, asthma, and other diseases of the immune system.

  • Pediatric allergist-immunologists specialize in caring for children from infancy through adolescence with allergies, asthma, and other diseases of the immune system.

  • Pulmonologists specialize in the medical care of people with breathing problems and diseases and conditions of the lungs.

  • Pediatric pulmonologists specialize in the medical care of infants, children and adolescents with diseases and conditions of the lungs.

How is spirometry performed?

Your spirometry will be performed in a hospital, office, or pulmonary function test lab. Proper technique is important for accurate spirometry measurements and may take a bit of practice to master. Spirometry takes about 15 to 30 minutes and generally involves these steps: 

  1. Loosen tight or restrictive clothing.

  2. You will apply a clip to your nose to keep your nostrils closed.

  3. Stand or sit up straight and breathe in as deeply as possible.

  4. Blow into the spirometer mouthpiece, breathing out as hard as you can for several seconds or for as long as directed until your lungs are empty. Make sure your lips make a good seal on the mouthpiece. The spirometer takes measurements at different times while you exhale and records them on a graph.

  5. You will perform this process at least three times to make sure your results are accurate and consistent.

  6. You may take an inhaled bronchodilator to open your breathing passages and then repeat the test to see how the medication affects your lungs.

Spirometry sometimes takes place inside a special clear cabinet or booth. This is called a body plethysmography. This test includes a computerized pulmonary function testing system that also performs other pulmonary function tests. 
Will I feel pain with spirometry?

Your comfort and relaxation is important for you and your care team, and will help obtain the most accurate spirometry readings. Spirometry is not painful, but you may feel short of breath or briefly lightheaded after the test. Tell your healthcare provider if this does not pass quickly or if you have any other symptoms.

What is a normal spirometry reading?

Spirometry measures many different lung function values. Your doctor will interpret the various measurements in relation to your age, symptoms, physical exam, medical history, and possibly other pulmonary function tests. Two key measurements are:

  • Forced vital capacity (FVC), which is the largest amount of air that you can forcefully exhale after breathing in as deeply as you can. A lower than normal FVC reading is a sign of restricted breathing.

  • Forced expiratory volume (FEV-1), which is how much air you can force from your lungs in one second. FEV-1 indicates the severity of your breathing problem. Low FEV-1 readings are a sign of more serious obstruction.

What are the risks and potential complications of spirometry?  

Spirometry is generally safe without serious risks or complications. Some people should not have spirometry including those with:

How do I prepare for my spirometry?

You are an important member of your own healthcare team. The steps you take before your procedure can improve your comfort and help obtain the most accurate test results.

You can prepare for spirometry by:

  • Not eating a large meal before the test

  • Not smoking

  • Stopping your medications before the test as directed by your doctor

  • Wearing loose, comfortable clothing

Questions to ask your doctor

It is common for patients to forget some of their questions during a doctor’s visit. You may also think of other questions after your appointment or after you leave the hospital Contact your doctor with concerns and questions before your procedure and between appointments.

It is also a good idea to bring a list of questions to your appointments. Questions can include:

  • Why do I need spirometry? What are the other options for diagnosing and monitoring my condition?

  • Who will perform my spirometry? Is this person a nurse, respiratory therapist, or pulmonary function technologist? Is this person certified to perform spirometry or has he or she had other special training?

  • How often will I need spirometry?

  • How should I take my medications before and after spirometry?

  • When and how can I expect to get my results?

  • When should I follow up with you?

  • How should I contact you? Ask for numbers to call during and after regular hours.

What can I expect after my spirometry?

Knowing what to expect after spirometry can help you get back to your everyday life as soon as possible.

How will I feel after my spirometry?

You should be breathing normally after your spirometry and you should not feel any ill effects of the test. Tell your nurse, respiratory therapist, or pulmonary function technologist if you are dizzy, short of breath, or have any other symptoms or concerns. 

When should I call my doctor?

It is important to keep your follow-up appointments after spirometry. Contact your doctor if you have any concerns between appointments or if you have breathing symptoms that are unusual or are not responding to your medications. Seek emergency medical care or call 911 if shortness of breath or other breathing problems are getting worse quickly.

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2020 Nov 10
View All Lungs, Breathing and Respiration Articles
THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
  1. An Approach to Interpreting Spirometry. American Academy of Family Physicians. http://www.aafp.org/afp/2004/0301/p1107.html.
  2. Platinum Elite™ body plethysmograph with RTD. Medgraphics Cardiopulmonary Diagnostics. http://mgcdiagnostics.com/products/view/platinum-elite-dl-with-rtd.
  3. Spirometry: how to take a lung function test.European Lung Foundation YouTube video. http://www.youtube.com/watch?v=6kbgZWS5wH0.
  4. Spirometry to measure breathing. University of Washington. http://www.spirometrytraining.org/.