mediastinal emphysema n.
A deflection of air, usually from a ruptured emphysematous bleb in the lung, into the mediastinal tissue.
pocket of air surrounding the heart and central blood vessels contained within the mediastinum (the central cavity in the chest situated between the lungs) that usually forms as a result of lung rupture. When the alveoli (air sacs) of the lungs rupture because of traumatic injury or lung disease, the released air seeks an area of escape. One pathway that the air can follow is through the lung tissue into the mediastinum, where accumulating air can cause sufficient pressure to impair normal heart expansion and blood circulation
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