Air trapping
Air trapping, also called gas trapping, is an abnormal retention of air in the
lungs where it is difficult to exhale completely.[1] It is observed in obstructive lung diseases such as asthma, bronchiolitis obliterans syndrome and chronic obstructive pulmonary diseases such as emphysema and chronic bronchitis
.
Air trapping is not a diagnosis but is a presentation of an illness, and can be a guide to the appropriate differential diagnosis.
Imaging
On
nonspecific interstitial pneumonia, and in early usual interstitial pneumonitis (the hallmark imaging diagnosis of interstitial lung disease) in which there is no change with inspiration and expiration.[citation needed
]
Measurement and function
Exhaled volumes are measured by a pulmonary function test or simple
computed tomography (CT) scanning. On expiratory films, retained hyperlucent gas will be visualised in cases of air trapping.[2]
Air trapping represents poorly aerated lung, but on its own is clinically benign. It is a common problem for smokers who dive. On diving the
lung volume collapses and pushes air into the poorly aerated regions. On arising from a deep depth, these air-trapped areas of lung expand. This places great pressure on the lung tissue which can rupture.[3]
References
- ^ U. Joseph Schoepf; "6.4.9.5 Expiratory Hyperinflation – Air Trapping", Multidetector-Row CT of the Thorax Birkhäuser, 2005, p.101
- ^ Javier Luca ya; A. L. Baert; Janet L. Strife; "4.6.5 Air Trapping", Pediatric Chest Imaging: Chest Imaging in Infants and Children, Springer, 2007, p. 92
- ^ Johny A. Verschakelen; W. De Weber; "5.2.2 Air Trapping", Computed Tomography of the Lung: A Pattern Approach, Springer, 2007, p. 51