[Dissecting emphysema].

We report six observations of pneumomediastinum, due to dental extraction and use of high speed air turbine drill, aspiration of a nut with air trapping, labor in delivery, status asthmaticus, mechanical ventilation, and rectal perforation. Some patients showed widespread extension of dissecting air presenting as subcutaneous emphysema, pneumopericardium or pneumoretroperitoneum. The mediastinum is thought to be a central pump, the diaphragm and the lung acting like bellows, which distribute interstitial air from and into communicating layers on both sides of the diaphragm. Pneumomediastinum does not prove an air leak in the thoracic cage nor does pneumoretroperitoneum absolutely indicate bowel rupture. Review of the literature.