What is Body Plethysmography (Static Lung Volumes)?

A test performed to more accurately assess total lung capacity, including any volume of air which may not be able to be expelled (gas trapping). Helps diagnose and manage lung diseases such as Emphysema and Interstitial Lung Disease. 

 

Explanation   

Determines total lung capacity (TLC) and residual volume (RV)—the amount of air remaining in your lungs after you exhale as much as possible. 

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How it is performed: 

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1. You sit inside an airtight, transparent glass enclosure (a body plethysmograph booth) with the door closed.

2. You place your hands flat against your cheeks to prevent them from puffing out. 

3. You breathe normally through the mouthpiece. 

4. A valve briefly blocks the airflow for 2–3 seconds while you make gentle, shallow "panting" breath efforts against the closed shutter. 

5. The machine measures subtle pressure changes inside the sealed box and at your mouth to calculate the exact volume of air in your chest.