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Pulmonary Function Test: Lung Volume Test (Plethysmography)

What is a Lung Volume Test (Plethysmography)?

The Division of Pulmonary Medicine at Cincinnati Children's performs lung function tests such as plethysmography. Plethysmography is also known as lung volumes.

Plethysmography measures how much air your lungs hold. Some disorders and diseases may decrease or increase this measurement.

Description of the Test

Plethysmography is done with your child sitting in an enclosed plexiglass chamber that allows your child and therapist to see in and out. The child and therapist will also be able to hear each other through the plexiglass. Your child will place padded nose clips on his or her nose and place their mouth around a single use, disposable, filtered mouthpiece.

Your child will place his or her hands on their cheeks, breathe normally and then pant in and out for a few seconds. After panting, your child will go back to breathing normally, blow out air and then take a deep breath.

Length of Test

Plethysmography is typically performed along with spirometry. Both tests combined can take up to 40 to 60 minutes.

Preparing Your Child for the Test

Please contact your physician or provider for instructions on holding medications.Possible Side Effects of the Test

There are no side effects. Your child may resume normal activities and medications after testing.

Last Updated 05/2022

Reviewed By Anna Baumer, RRT