- Etiology: barotrauma, blunt thoracic trauma
- CXR upright: gravity drops lung inferiorly and medially and shows distinct pleural edge with no lung markings lateral to it
- CXR decubitus: gravity drops lung inferiorly and shows distinct pleural edge with no lung markings superior to it
- CXR cross-table lateral: gravity drops lung inferiorly and may show pleural edge with no lung markings anterior to it – but does not tell you which side the pneumothorax is on
- CXR supine: gravity drops lung posteriorly and usually fails to reveal pleural edge, air accumulates anteromedially so pneumothorax can manifest itself as increased lucency throughout hemithorax / sharp heart border / deep sulcus sign = increased lucency in costophrenic angle / asymmetrical lucency of lungs
- CT: most sensitive for detection of pneumothorax, useful in patients who can only lie supine, excellent for determining chest tube position
- Note: if you suspect small pneumothorax on CXR supine get decubitus image with suspected side up to confirm
- Note: tension pneumothorax is diagnosed when there is mediastinal shift which implies underlying tension
- DDX: skin fold
- Complications: tension pneumothorax causes torquing of great vessels, vascular compromise, requires immediate treatment
- Clinical: in premature infant lungs are stiff (noncompliant) so don’t collapse like adult lung