What causes tension pneumothorax?

A tension pneumothorax occurs when air enters the pleural space and cannot escape, creating increased pressure that collapses the lung on the affected side and can push the mediastinum toward the opposite side. The most common cause of this condition is an open chest wound, often referred to as a "sucking" chest wound, where external air is allowed to enter the pleural cavity with each breath but cannot be exhaled. This results in a buildup of pressure that can lead to life-threatening complications, such as cardiovascular collapse.

While other factors like external bleeding may contribute to overall patient instability, or individuals may experience difficulties with breathing techniques and hydration levels, these do not directly lead to the formation of a tension pneumothorax. The hallmark of tension pneumothorax is the inability of air to exit the pleural space, making an open chest wound the most significant contributing factor for this specific medical emergency.