Received 5 March 2011, Accepted 24 March 2011, Available online 23 June 2011. Spontaneous pneumomediastinum is defined as free air within the mediastinum, not associated with trauma. Causes include exercise, drugs, asthma, vomiting, difficult labour and Valsalva maneuvers. Itâs a rare, usually benign and self-limited condition, more prevalent in young males.
A youth bouncing on a trampoline. A trampoline is a device consisting of a piece of taut, strong fabric stretched over a steel frame using many coiled springs. People bounce on trampolines for recreational and competitive purposes.
In the early 1930s, George Nissen observed trapeze artistes performing tricks when bouncing off the safety net. He made the first modern trampoline in his garage to reproduce this on a smaller scale and used it to help with his diving and tumbling activities.