Body Plethysmography

Medically Reviewed By William C. Lloyd III, MD, FACS
Was this helpful?

What is body plethysmography?

Body plethysmography is a simple, painless test that takes lung volume measurements. Lung volume is the amount of air you inhale and exhale. The test involves sitting in an airtight booth and blowing into a mouthpiece while a computer records measurements. Body plethysmography helps diagnose respiratory diseases with similar symptoms, including asthma, pulmonary fibrosis, and chronic obstructive pulmonary disease (COPD). 

Body plethysmography is only one method used to diagnose and manage respiratory diseases. Discuss all your testing options with your doctor to understand which tests are best for you.  

Other procedures that may be performed

Body plethysmography is a type of pulmonary (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 blood levels and other factors

  • Bronchoprovocation tests to measure lung function after exposure to factors that commonly trigger asthma. This includes a methacholine challenge test to help diagnose asthma. Some bronchoprovocation tests are done at the same time as body plethysmography using the same equipment.

  • Lung diffusion capacity to measure how well oxygen moves into your blood from your lungs. Lung diffusion capacity may be done at the same time as body plethysmography using the same equipment.

  • 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

  • Spirometry to measure the rate and the amount of air that you inhale and exhale. Spirometry may be done at the same time as body plethysmography using the same equipment.

Why is body plethysmography used? 

Body plethysmography is the most accurate method and sometimes the only way to take certain lung volume measurements. Lung volume is the amount of air you breathe in and out of your lungs. There are many kinds of lung volume measurements, which are measured using various pulmonary function tests, such as spirometry

Body plethysmography can diagnose respiratory diseases earlier than spirometry. It also helps your doctor determine if your symptoms are due to a restrictive or an obstructive disease. 

Restrictive lung diseases make it hard for you to fully expand your lungs and fill them with air. They include: 

  • Asbestosis, which is chronic inflammation and fibrosis of the lungs due to asbestos exposure

  • Neuromuscular diseases including muscular dystrophy and amyotrophic lateral sclerosis (ALS or Lou Gehrig’s disease)

  • Pulmonary fibrosis, which is lung scarring from growth of excessive fibrous tissue in the lungs

  • Sarcoidosis, which is inflammation of the body’s organs, leading to the formation of lumps (granulomas) in the lungs

  • Scoliosis, which is abnormal sideways curving of the spine

Obstructive lung diseases make it hard for you to exhale all the air out of your lungs. They include:

  • Asthma, which is a chronic lung disease marked by acute flare-ups of inflammation and swelling of the lung’s airways

  • Bronchiectasis, which is permanent inflammation and widening of the airways leading to mucus blockage

  • Chronic obstructive pulmonary disease (COPD), which includes emphysema and chronic bronchitis

  • Cystic fibrosis, which is a genetic disorder that causes thick, sticky mucus build-up in the lungs and other organs

Who performs body plethysmography?

A pulmonary function technologist usually performs body plethysmography. A pulmonary function technologist has specialized training and education to perform pulmonary function tests safely and accurately. 

The following physician specialists order and interpret body plethysmography tests:

  • Allergist/immunologists are internists or pediatricians with specialized training in the diagnosis and treatment of allergies, asthma, and immune deficiency disorders.

  • Pulmonologists are internists or pediatricians with specialized training in treating diseases and conditions of the chest. Examples include pneumonia, asthma, tuberculosis, emphysema, or complicated chest infections.

How is body plethysmography performed?

Your body plethysmography will be performed in a hospital pulmonary function lab or sometimes in a pulmonologist’s office. Lung volume measurements take as little as three minutes, but the entire procedure will take about 20 to 30 minutes.  

Proper breathing technique is important for accurate body plethysmography measurements and may take a bit of practice to master. 

Body plethysmography generally involves these steps: 

  1. You will loosen tight or restrictive clothing.

  2. You will sit or stand inside a clear, airtight chamber or booth and spend about 45 seconds acclimating to the temperature in the booth.

  3. You will inhale and exhale through a mouthpiece against a closed shutter device to a particular volume. Your pulmonary function technologist will instruct you to use different breathing techniques, such as panting and normal breathing.

  4. Your chest volume will expand and increase the pressure in the box as you breathe against the shutter. This pressure reading determines lung volume measurements.

  5. Your pulmonary function technologist may perform other pulmonary function tests in the booth, such as spirometry and lung diffusion capacity.

Will I feel pain with body plethysmography?

Your comfort and relaxation is important and helps get the most accurate test results. A body plethysmography is not painful, but some people feel closed in or claustrophobic in the booth. Keep in mind that the booth is clear and the door can be opened from the inside. Tell your pulmonary function technologist if you are uncomfortable in any way or have shortness of breath, wheezing, or any other symptoms during the test.

What is a normal body plethysmography reading?

Body plethysmography measures many lung function values that are complex to interpret. Your doctor will evaluate the measurements in relation to your age, symptoms, physical exam, medical history, and possibly other pulmonary function tests. Your doctor will discuss what the results mean to you. 

What are the risks and potential complications of body plethysmography?  

Body plethysmography is a safe procedure without serious risks or complications. However, people with the following conditions may not tolerate body plethysmography:

  • Claustrophobia

  • Mental confusion

  • Any condition requiring continuous oxygen therapy that cannot be stopped to take the test

How do I prepare for my body plethysmography?

Remember that you are an important member of your own healthcare team. You can prepare for body plethysmography by:

  • Not eating a large meal before the test

  • 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 appointment. Common questions include:

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

  • Who will perform my body plethysmography? Is this person a certified pulmonary function technologist?

  • How should I take my medications?

  • 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 body plethysmography?

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

How will I feel after my body plethysmography?

You should be breathing normally and not feel any ill effects after body plethysmography. Tell your doctor or provider if you are dizzy, short of breath, or have other symptoms. 

When should I call my doctor?

It is important to keep your follow-up appointments after body plethysmography. Contact your doctor for questions and concerns between appointments. Call your doctor right away or seek immediate medical care if you have breathing symptoms that are unusual or not responding to your medications.

Was this helpful?
Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2020 Nov 15
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. Body Plethysmography. Johns Hopkins School of Medicine.
  2. Body Plethysmography Features & Specifications. Morgan Scientific, Inc.
  3. Obstructive Lung Diseases. McGraw-Hill Companies.
  4. Restrictive Lung Disease. Johns Hopkins Children’s Center.
  5. Restrictive Lung Disease. MedCentral Health System.
  6. Whole-body plethysmography. RT: For Decision Makers in Respiratory Care.