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.
Lung infections should be treated promptly. Many cases are not preventable. A chest tube is inserted through the chest wall between the ribs. The chest tube is attached to a vacuum bottle which slowly and continuously removes air from the chest cavity. This allows the lung to re-expand.