Pneumomediastinum (from Greek pneuma – "air", also known as mediastinal emphysema) is pneumatosis (abnormal presence of air or other gas) in the mediastinum. First described in 1819 by René Laennec, the condition can result from physical trauma or other situations that lead to air escaping from the lungs, airways, or bowel into the chest cavity. In underwater divers it is usually the result of pulmonary barotrauma. Signs and symptoms
The main symptom is usually severe central chest pain. Other symptoms include laboured breathing, voice distortion (as with helium) and subcutaneous emphysema, specifically affecting the face, neck, and chest. Pneumomediastinum can also be characterized by the shortness of breath that is typical of a respiratory system problem. It is often recognized on auscultation by a "crunching" sound timed with the cardiac cycle (Hammans crunch). Pneumomediastinum may also present with symptoms mimicking cardiac tamponade as a result of the increased intrapulmonary pressure on venous flow to the heart. Cause
It is most commonly caused by:
Esophageal rupture, for example in Boerhaave syndrome
Asthma or other conditions leading to alveolar rupture
Bowel rupture, where air in the abdominal cavity tracts up into the chest.It has also been associated with:

Mycoplasma pneumoniae pneumonia
obesityIt can be induced to assist thoracoscopic surgery.It can be caused by a pulmonary barotrauma induced by a person moving from a higher to a lower pressure environment, such as when a scuba or surface-supplied diver, a free-diver after lung-packing,  or an airplane passenger ascends.
Surgery may be needed to repair the hole in the trachea, esophagus or bowel.If there is lung collapse, it is imperative the affected individual lies on the side of the collapse. Although painful, this allows full inflation of the unaffected lung. References
External links

00964 at CHORUS