What mechanism is primarily involved in a tension pneumothorax?

A tension pneumothorax occurs when air becomes trapped in the pleural space and cannot escape, leading to increased pressure within the thoracic cavity. This situation is primarily due to a one-way valve effect, which happens when air enters the pleural space during inhalation but cannot be expelled during exhalation. As more air continues to enter the pleural space, the pressure rises, which can cause the lung on the affected side to collapse and shift mediastinal structures, leading to severe respiratory and cardiovascular compromise.

This mechanism differs significantly from fluid accumulation in the pleural cavity, which describes pleural effusion rather than pneumothorax. A ruptured bronchus could lead to air escaping into the surrounding tissue or a different type of pneumothorax, but it does not specifically describe the one-way valve mechanism causing a tension pneumothorax. Pulmonary infections can cause various complications but are not related to the pressure dynamics of a tension pneumothorax. Understanding this mechanism is crucial for recognizing the urgent nature of tension pneumothorax and the need for immediate intervention, typically involving the decompression of the pleural space to relieve pressure.