What causes a tension pneumothorax, resulting in lung collapse?

A tension pneumothorax occurs when air enters the pleural space—the cavity surrounding the lungs—typically due to a breach in the lung or chest wall. This breach allows air to enter but not escape, leading to increased pressure within the pleural cavity. As this pressure builds, it can push against the lung, preventing it from expanding fully during inhalation, and can also compress nearby structures, including the heart and major blood vessels. This buildup of air ultimately results in the collapse of the lung on the affected side, which is the hallmark of a tension pneumothorax.

In contrast, options such as blood entering the chest or fluid accumulation would result in different types of conditions, such as a hemothorax or pleural effusion, rather than a tension pneumothorax. Aspiration of food could lead to other complications, like an aspiration pneumonia, but it does not directly cause a tension pneumothorax. Understanding these distinctions is crucial for effective assessment and management of thoracic injuries in emergency response scenarios.