Which condition involves a life-threatening collection of air within the pleural space, collapsing the lung?

Tension pneumothorax is a critical condition where air accumulates in the pleural space, exerting pressure on the lung and causing it to collapse. This occurs due to a one-way valve effect, where air can enter the pleural cavity but cannot escape, leading to increasing pressure that compromises respiratory function and circulatory stability. As the pressure builds, it not only collapses the lung on the affected side but can also push the mediastinum away from the affected side, potentially compressing the heart and large blood vessels, which can lead to cardiovascular compromise and shock.

In contrast, flail chest involves multiple rib fractures resulting in a segment of the chest wall moving independently of the thoracic cavity, but it does not involve air within the pleural space in a way that poses the same immediate life-threatening pressure. Pneumatic splints and traction splints are devices used for stabilizing fractures and do not relate to conditions affecting the pleural space or lung collapse.