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Body Plethysmography

Patient information A-Z

a picture of lung function test equipment being used by a person for performing body plethysmography. The body plethysmograph is a perspex cubicle, similar to a telephone box, that has a chair and breathing arm with mouthpiece inside.
Lung function test equipment being used

What is body plethysmography?

Body Plethysmography is a breathing assessment which can provide a variety of specialities with important information regarding your breathing and may indicate whether further assessment is required. It can be performed as a single test. However, in most cases this test is performed in conjunction with other tests. It can be performed on subjects of all ages from five years upwards.

Why am I having a body plethysmography test?

Body plethysmography is used to assess two aspects of your breathing; the resistance or narrowing within the airways and the total amount of air inside your lungs. This includes the amount of air that you can breathe in and out, and the amount left inside the lungs when you have blown everything out.

What does body plethysmography involve?

During body plethysmography you will be required to sit inside a cubicle with the door closed throughout the test. Please note the door is not locked and can be opened voluntarily at any point if required. In front of you will be a mouthpiece to use for the test and you will be given a peg to use on your nose when instructed.

First of all, we will wait for one minute in order to allow the temperature to settle. You will then be asked to breathe slightly quicker than normal on the mouthpiece whilst holding your cheeks and with the peg on your nose. After 30 to 60 seconds a shutter will block the mouthpiece for two seconds. During this time, you will be asked to pant softly against the blockage. After two seconds the shutter will lift and you will then be asked to breathe in fully before blowing all the way out to empty in a controlled manner like a sigh. The test finishes with a big breath back in to full.


Please take all medication including inhalers as normal (unless otherwise stated in your appointment letter)

The test can last approximately 10-30 minutes.

What if I am unwell prior to the appointment?

Please contact the department using the details stated if you have had a recent chest infection, are currently on a course of antibiotics or have just finished a course of antibiotics for your chest. As a result, it may not be appropriate to perform the test at this time and your appointment may be rescheduled.

If you are unwell please inform the department at the earliest possible opportunity. However, if you are unwell on the day of the appointment please still call and let us know as this will allow us to rearrange your appointment for a more suitable time.

Who will be present at my appointment?

CUH Addenbrooke’s NHS Trust is a teaching hospital and therefore there may be occasions when a student or other staff members accompany your physiologist. However, we will always seek your permission first.

Test results

After your appointment your test results will be sent to your referring consultant, who will then contact you to discuss the results and the next steps in your pathway.


You will be asked for consent to perform tests during your appointment. You will also have an opportunity to ask questions regarding the test before you give consent. In the unlikely event there are risks related to the test, these will be discussed with you before the test starts.


Due to the nature of the tests and the exertion required, some patients may feel dizzy or faint during testing, coughing is also common. Serious complications are rare and risks will be kept to a minimum by your physiologist.

This test involves sitting inside a cubicle with the door closed for a period of time; this can be difficult for those with claustrophobia. Please be sure to tell the physiologist of any concerns.

During this test, it may also become very warm inside the cubicle. Do not hesitate to inform the physiologist, who will open the door and allow for breaks between tests.

Potential serious but rare complications

  • Airway narrowing in those with sensitive airways.
  • Heart attack in patients with previous cardiac disease.
  • Sudden changes in blood pressure.
  • Stroke.
  • Collapsed lung.
  • Retinal detachment.

These complications are very rare. You will be questioned by your physiologist prior to doing the tests to ascertain whether you are at increased risk.

If you cannot attend your appointment

If you need to rearrange your appointment, or no longer need an appointment, please call us on Lung function department appointment number at the earliest possible opportunity to advise. The ability to reallocate appointments helps us to reduce waiting times.

Contacts/further information

If you are unsure about any of the information provided in this leaflet or have any other questions then please do not hesitate to contact the lung function department at Addenbrooke’s hospital on Lung function department number or alternatively by contacting clinic 2A on Clinic 2A number.

Our opening hours are Monday-Friday from 08:30 to 16:30.

We are smoke-free

Smoking is not allowed anywhere on the hospital campus. For advice and support in quitting, contact your GP or the free NHS stop smoking helpline on 0800 169 0 169.

Other formats

Help accessing this information in other formats is available. To find out more about the services we provide, please visit our patient information help page (see link below) or telephone 01223 256998.

Contact us

Cambridge University Hospitals
NHS Foundation Trust
Hills Road, Cambridge

Telephone +44 (0)1223 245151