pneumothorax

pneumothorax, condition 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.) Different classifications are used to describe the various types of pneumothoraxes, though two major types commonly are recognized: traumatic pneumothorax, which includes accidental and iatrogenic (medically caused) pneumothoraxes, and spontaneous (nontraumatic) pneumothorax.

Traumatic pneumothorax is the accumulation of air caused by penetrating chest wounds (e.g, knife stabbing, gunshot) or other injuries to the chest wall, after which air is sucked through the opening and into the pleural sac. Similar injury can be caused by invasive medical procedures, such as fine needle aspiration or pleural biopsy, resulting in iatrogenic pneumothorax.

Spontaneous pneumothorax is the passage of air into the pleural sac from an abnormal connection created between the pleura and the bronchial system. It may be characterized as either of two types: primary, in which the patient has no prior thoracic trauma or predisposing lung condition, or secondary, being associated with 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.

Pneumothorax may also be described as either a simple pneumothorax, without effects on the heart or mediastinal structures, or as a tension pneumothorax, which is a life-threatening condition. Tension pneumothorax 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 the 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.