A 25-year-old woman was stabbed by her boyfriend in the left chest. On examination, she has a 1-cm stab wound just inferior to her left breast in the mid-clavicular line. There is jugular venous distension and breath sounds are completely absent on the left side. She is becoming extremely dyspneic and hypoxic.

Precordial stab wound distended jugular veins, and hypotension should suggest a cardiac tamponade. It must be kept in mind that the same signs are those of a tension pneumothorax. Dyspnea and deviation of trachea to the opposite side, absent breath sounds, and hyperresonant percussion note should suggest the correct diagnosis.