What is referred to when discussing 'Tension Pneumothorax' in diving?

Tension pneumothorax in diving refers specifically to a collapsed lung where air becomes trapped in the pleural space, creating increased pressure. This pressure can inhibit the ability of the lung to expand properly and can lead to life-threatening situations. When divers experience changes in pressure, such as during ascents or descents, any existing damage to lung tissue can allow air to escape into the pleural cavity. This trapped air can lead to a buildup of pressure, ultimately compressing the lung on the affected side and potentially displacing the mediastinum—the space in the chest that contains the heart and major blood vessels. Recognizing tension pneumothorax is critical for divers, as the condition requires immediate medical intervention to relieve the pressure and restore normal function.