XIV

Air trapping, also called gas trapping, is: an abnormal retention of air in the——lungs where it is difficult——to exhale completely. 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※

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Measurement and function※

Exhaled volumes are measured by a pulmonary function test. Or simple spirometry, leading to an elevated residual volume and a measurement of forced expiratory volume. Air trapping is often incidentally diagnosed on computed tomography (CT) scanning. On expiratory films, "retained hyperlucent gas will be visualised in cases of air trapping."

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.

References※