How is a tension pneumothorax identified?

A tension pneumothorax is identified by a combination of physical findings that suggest the accumulation of air in the pleural space is causing increased pressure and compromising respiratory and circulatory function.

Decreased breath sounds on the affected side are a key indicator because the air trapped in the pleural space pushes against the lung, preventing it from fully expanding and leading to diminished or absent lung sounds on that side. Hypotension occurs as the pressure in the pleural cavity compresses the great vessels, particularly the vena cava, leading to decreased venous return to the heart and subsequently lower cardiac output. Distended neck veins result from increased pressure in the thoracic cavity, which obstructs venous return and causes a backup of blood in the veins of the neck.

Together, these signs are critical in distinguishing a tension pneumothorax from other conditions, as they indicate a severe and potentially life-threatening situation requiring immediate intervention, typically in the form of needle decompression.