Pneumothorax

In medicine (pulmonology), a pneumothorax or collapsed lung is a medical emergency caused by the collapse of the lung within the chest cavity. It can result from a penetrating chest wound or barotrauma to the lungs. Additionally, it can develop spontaneously in predisposed individuals (tall, slim individuals who smoke; young males have a higher risk than females). more...

Signs and symptoms

Sudden shortness of breath, cyanosis (turning blue) and pain felt in the chest and/or back are the main symptoms. In penetrating chest wounds, the sound of air flowing through the puncture hole may indicate pneumothorax. The flopping sound of the punctured lung is occasionally heard.

If untreated, the hypoxia will lead to loss of consciousness and coma. In addition, shifting of the mediastinum towards the site of the injury can obstruct the aorta and other large blood vessels, depriving distal tissues of blood. Untreated, a severe pneumothorax can lead to death within several minutes.

Spontaneous pneumothoraces are reported in young people with a tall stature. As men are generally taller than women, there is a preponderance among males. The reason for this association, while unknown, is hypothesized to be the presence of subtle abnormalities in connective tissue.

Pneumothorax can also occur as part of medical procedures, such as the insertion of a central venous catheter (an intravenous catheter) in the subclavian vein (vena subclavia) or jugular vein (vena jugularis). While rare, it is considered a serious complication and needs immediate treatment. Other causes include mechanical ventilation, emphysema and rarely other lung diseases (pneumonia).

Diagnosis

The absence of audible breath sounds through a stethoscope can indicate that the lung is not unfolded in the pleural cavity. This accompanied by hyperresonance (higher pitched sounds than normal) to percussion of the chest wall is suggestive of the diagnosis. If the signs and symptoms are doubtful, an X-ray of the chest can be performed, but in severe hypoxia, emergency treatment has to be administered first.

In a supine chest X-ray the deep sulcus sign is diagnostic, which is characterized by a low lateral costophrenic angle on the affected side. Stated differently, the place where rib and diaphragm meet appears lower on an X-ray with a deep sulcus sign and suggests the diagnosis of pneumothorax.

Pathophysiology

The lungs are located inside the chest cavity, which is a hollow space. Air is drawn into the lungs by the diaphragm (a powerful abdominal muscle). The pleural cavity is the region between the chest wall and the lungs. If air enters the pleural cavity, either from the outside (open pneumothorax) or from the lung (closed pneumothorax), the lung collapses and it becomes mechanically impossible for the injured person to breathe, even with a patent airway. If a piece of tissue forms a one-way valve that allows air to enter the pleural cavity from the lung but not to escape, overpressure can build up with every breath; this is known as tension pneumothorax. It may lead to severe shortness of breath as well as circulatory collapse, both life-threatening conditions. This condition requires urgent intervention.

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