What happens in the body during a tension pneumothorax?

In the case of a tension pneumothorax, what really happens is an increase in pressure within the thoracic cavity due to air trapping. This condition occurs when air enters the pleural space and cannot escape, leading to a progressive buildup of pressure. As a result, this increased intrathoracic pressure compresses the lung on the affected side, which impairs its ability to expand and can lead to lung collapse. Consequently, the risk of lung collapse is heightened due to the combination of this increased pressure and the exclusion of air from the pleural space that hinders normal lung function.

Additionally, the elevated pressure can also compress major vessels such as the vena cava, leading to compromised venous return to the heart, which significantly affects cardiac output and can result in hemodynamic instability. Therefore, understanding the implications of pressure dynamics in the thoracic cavity highlights why "increased risk of lung collapse" accurately represents one of the critical consequences of a tension pneumothorax.