Aetiology

It can result from:

• A penetrating chest wound

• Barotrauma to the lungs

• Spontaneously (most commonly in tall slim young males and in Marfan syndrome)

• Chronic lung pathologies including emphysema, asthma

• Acute infections

• Acupuncture

• Chronic infections, such as tuberculosis

• Cancer

• Catamenial pneumothorax (due to endometriosis in the chest cavity)

Pneumothoraces are divided into tension and non-tension pneumathoraces. A tension pneumothorax is a medical emergency as air accumulates in the pleural space with each breath. The remorseless increase in intrathoracic pressure results in massive shifts of the mediastinum away from the affected lung compressing intrathoracic vessels. A non-tension pneumothorax by contrast is a less severe pathology because the air in the pneumothorax is able to escape.

The accumulation of blood in the thoracic cavity (hemothorax) exacerbates the problem, creating a pneumohemothorax.

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, hence the term "sucking" chest wound. The flopping sound of the punctured lung is also occasionally heard.

If untreated, hypoxia may lead to loss of consciousness and coma. In addition, shifting of the mediastinum away from the site of the injury can obstruct the superior and inferior vena cava resulting in reduced cardiac preload and decreased cardiac output. 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 or jugular vein. 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^[2], which is characterized by a low lateral costophrenic angle on the affected side.^[3] In layman's terms, the place where rib and diaphragm meet appears lower on an X-ray with a deep sulcus sign and suggests the diagnosis of pneumothorax.