A punctured lung; this can happen from an outside wound, or on the inside from a broken rib, other lung diseases, or just completely on its own. Air escapes and gets trapped in the pleural space (within the linings of the lung — see Diagram — Lung Anatomy). Tall slender persons may be at more risk for it to happen without reason. Pneumothoraxes are not very common.
The main symptom is chest pain that begins abruptly and hurts with every breath. There’s no cough or phlegm, and no fever. There’s often shortness of breath; maybe not if the pneumothorax is mild.
We suspect it by hearing differences in lung sounds between right & left; diagnosis is easy by Chest X-ray. Treatment is usually successful in a hospital, inserting a tube into the pleural space under regulated pressure that prevents more air from entering, until the lung heals.
With a rare type called “tension pneumothorax,” air keeps on entering, creating pressure on the heart. Blood can’t circulate, patients lose their blood pressure, may turn blue in the face, & can die quickly. Ambulance paramedics usually know how to help this on the spot.