pneumothorax, Left-sided pneumothorax (on the right side of image) on computed tomography (CT) scan of the chest.Clinical Casescondition in which air accumulates in the pleural space, causing it to expand and thus compress the underlying lung, which may then collapse. (The pleural space is a cavity formed by the two pleural membranes that line the thoracic cavity and cover the lungs.) There are three major types of pneumothorax: traumatic pneumothorax, spontaneous pneumothorax, and tension pneumothorax.

Traumatic pneumothorax is the accumulation of air caused by penetrating chest wounds (knife stabbing, gunshot) or other injuries to the chest wall, after which air is sucked through the opening and into the pleural sac.

Spontaneous pneumothorax is the passage of air into the pleural sac from an abnormal connection created between the pleura and the bronchial system as a result of bullous emphysema or some other lung disease. The symptoms of spontaneous pneumothorax are a sharp pain in one side of the chest and shortness of breath.

Tension pneumothorax is a life-threatening condition that can occur as a result of trauma, lung infection, or medical procedures, such as high-pressure mechanical ventilation, chest compression during cardiopulmonary resuscitation (CPR), or thoracoscopy (closed-lung biopsy). In contrast to traumatic pneumothorax and spontaneous pneumothorax, in tension pneumothorax air that becomes trapped in the pleural space cannot escape. As a result, with each breath the patient inhales, air and pressure accumulate within the chest. When the lung on the affected side of the chest collapses, the heart, blood vessels, and airways are pushed to the centre of the chest, thereby compressing the other lung. This leads to decreases in blood pressure, consciousness, and breathing that in turn may lead to shock and death.

Most pneumothoraxes can be treated by inserting a tube through the chest wall. This procedure allows air to escape from the chest cavity, which enables the lung to re-expand. In some cases, a catheter connected to a vacuum system is required to re-expand the lung. While small pneumothoraxes may resolve spontaneously, others may require surgery to prevent recurrences.