Editing Pneumothorax (section)

== Imaging ==

* Standard erect CXR in inspiration. Expiration films can help to diagnose a small PTX (decreases lung volume, but doesn't decrease the volume of air, so relative increase in size of PTX)
* Signs of PTX on supine films
** Air collects anteriorly, in front of the lungs
** Relative lucency of ipsilateral lung
** Deep sulcus sign
** Increased sharpness of adjacent mediastinal margin and diaphragm
** Double diaphragm sign, from visualisation of the anterior costophrenic sulcus
** Depression of ipsilateral hemidiaphragm
* CT for uncertain cases, to assess aetiology
* Quantifying PTX
** Size is less important than degree of clinical compromise
** Complicated formulas are available, but impractical, requiring CT
** Best is to describe 'small PTX' as one with the surface of the lung <3cm from the chest wall
** Large PTX >3cm to chest wall