Pneumothorax

Pneumothorax can be subdivided into three categories, depending on whether air has direct access to the pleural cavity. In simple pneumothorax, no communication exists with the atmosphere. Additionally, no shift of the mediastinum or hemidiaphragm results from the accumulation of air in the intrapleural space. The severity of pneumothoraces is graded on the basis of the degree of collapse: collapse of 15% or less is small, collapse of 15% to 60% is moderate, and collapse of greater than 60% is large. Treatment of simple pneumothorax is determined by the size and cause of injury and may include catheter aspiration or tube thoracostomy; close observation of the patient with simple pneumothorax is essential.

In communicating pneumothorax, air in the pleural cavity exchanges with atmospheric air through a defect in the chest wall. Because the exchange of air through the site of injury may often be heard, this entity is commonly known as a “sucking chest wound.” Treatment measures include administration of supplemental oxygen, tube thoracostomy, and intubation; mechanical ventilation may be indicated.

Tension pneumothorax develops when air progressively accumulates under pressure within the pleural cavity. If the pressure becomes too great, the mediastinum shifts to the opposite hemithorax, and this causes compression of the contralateral lung and great vessels. Tension pneumothorax is potentially lethal; therefore, immediate treatment is essential. Decompression of the chest can be performed with the insertion of a 16- or 18-gauge angiocatheter into the second or third interspace anteriorly or the fourth or fifth interspace laterally. A rush of air is heard when decompression occurs. The angiocatheter must be covered if the sucking of more air into the pleura is to be prevented.