plethysmography
Pronunciation: pluh-THIZ-mog-ruh-fee
Pulmonary function test performed in a sealed chamber to measure lung volumes and airway resistance using pressure and flow changes.
Full Definition
Plethysmography is an advanced pulmonary function test performed in a sealed, transparent chamber called a body plethysmograph or "body box." The test measures thoracic gas volume, functional residual capacity, and airway resistance by detecting small pressure changes within the chamber that occur during breathing efforts against a closed shutter. When the patient attempts to breathe against the closed airway, thoracic gas compression and decompression create measurable pressure variations in both the patient's chest and the surrounding chamber. This technique provides the most accurate measurement of total lung capacity and can detect gas trapping that might be missed by other pulmonary function tests. Plethysmography is particularly valuable for diagnosing restrictive lung diseases, assessing air trapping in obstructive conditions, and measuring lung volumes in patients who cannot perform adequate spirometry maneuvers.
In Context
- "Plethysmography revealed significant air trapping with a total lung capacity of 150% of predicted values." — Pulmonary function report
- "The patient completed plethysmography testing in the body box to obtain accurate lung volume measurements." — Diagnostic procedure note