Pneumomediastinum
Dr Ian Bickle and Dr Martin Gorrochategui et al.
Pneumomediastinum is the presence of extraluminal gas within the mediastinum. Gas may come from lungs, trachea, central bronchi, oesophagus, and the neck or abdomen.
Aetiology
- blunt chest trauma
- secondary to chest, neck, or retorperitoneal surgery
- oesophageal perforation :
- Boerhaave syndrome
- endoscopic intervention
- oesophageal carcinoma
- tracheobronchial perforation :
- laceration
- bronchial stump dehiscence
- bronchoscopy
- tracheostomy
- laryngeal fracture
- vigorous exercise :
- childbirth
- weightlifting
- valsalva maneuver
- asthma
- barotrauma :
- diving
- ventilator : most commonly secondary to ARDS with positive pressure ventilation
- subcutaneous emphysema, pulmonary interstitial emphysema
- stab wound
- infection :
- tuberculosis
- histoplasmosis
- dental or retropharyngeal infection
- mediastinitis
- idiopathic
Radiographic features
Small amounts of air appear as linear or curvilinear lucencies outlining mediastinal contours such as
- subcutaneous emphysema
- elevated thymus : thymic wing sign
- air anterior to pericardium : pneumopericardium
- air around pulmonary artery and main branches : ring around artery sign
- air outlining major aortic branches : tubular artery sign
- air outlining bronchial wall : double bronchial wall sign
- continuous diaphragm sign : due to air trapped posterior to pericardium
- air between parietal pleura and diaphragm : extrapleural sign
- air in pulmonary ligament
- Naclerios V sign
Differential diagnosis
Must be distinguished most importantly from :
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