Air may accumulate in the mediastinum or pericardium following trauma.


Possible causes:

(1) injury to the airway (larynx, trachea, or major bronchus, including tracheal intubation)

(2) rupture of the pharynx (which may follow failed endotracheal intubation) or esophagus

(3) rupture of an emphysematous bulla at the lung apex

(4) mechanical ventilation

(5) pneumothorax

(6) penetrating trauma

(7) idiopathic


Clinical features of pneumomediastinum:

(1) subcutaneous emphysema over the upper thorax and neck

(2) Hamman's sign (crunching sound heard on auscultation of the heart during systole)


Clinical features of pneumopericardium:

(1) Bruit de Moulin (precordial murmur caused by turbulence of air and fluid in the pericardial cavity)

(2) tension pericardium with extrinsic compression on the heart and major veins


The air accumulation may be detected on a chest X-ray but often is better seen on a CT scan.


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