What causes a tension pneumothorax?

A tension pneumothorax occurs when air enters the pleural space and cannot escape, leading to increased pressure that can collapse the lung and push the mediastinum, which contains vital structures, such as the heart and major blood vessels. This accumulation of air creates a pressure imbalance, causing severe respiratory distress and cardiovascular compromise.

The correct understanding hinges on recognizing that the pleural space is meant to contain a small amount of fluid to facilitate lung expansion during breathing. When air accumulates instead—often due to trauma or a ruptured lung—this can result in tension pneumothorax. Immediate medical intervention is crucial, as it can be life-threatening.

The other options, while they refer to various respiratory and medical issues, do not describe the underlying mechanism of a tension pneumothorax. Excess fluid in the lungs can lead to pulmonary congestion but is not the source of pressure buildup seen in a tension pneumothorax. Pneumonia results in infection and fluid buildup but does not typically cause air to be trapped under pressure in the pleural space. A laceration of the chest could theoretically lead to a pneumothorax, but without the air trapping aspect, there is no progression to a tension state.