Tension pneumothorax

Definition:

A complete collapse of the lung that occurs when air enters, but does not leave, the pleural space. A mediastinal shift (displacement of the organs of the chest to the opposite side) occurs. See also pneumothorax.

Causes, incidence, and risk factors:

In tension pneumothorax, air enters the pleural space with each breath, is not expelled by exhaling, and becomes trapped. The trapped air builds up pressure in the chest, as the amount of trapped air accumulates. If untreated, the lung collapses on the affected side and may cause a mediastinal shift in which the heart, trachea, esophagus, and great vessels are pushed towards the unaffected side of the chest. The shift may cause compression of the opposite lung and may affect the flow of blood returning to the heart. Causes include penetrating trauma to the chest, lung infection, mechanical ventilation with high pressures, and as a complication of cardio-pulmonary resuscitation. Tension pneumothorax is a life-threatening emergency.