Tension pneumothorax is distinguished from simple pneumothorax by which sign?

• A. Increasing heart rate
• B. Stable vitals
• C. Falling blood pressure
• D. No chest pain

Answer: (C)

The sign that separates a tension pneumothorax from a simple one is a drop in blood pressure. When air accumulates under pressure in the chest, it squeezes the heart and great veins, cutting off venous return to the heart. That reduces preload and cardiac output, leading to hypotension and signs of shock, often with rapid heart rate and severe dyspnea. In a simple pneumothorax, the air in the pleural space can cause chest pain and breathing difficulty but usually doesn’t compromise circulation to the same extent, so vital signs don’t typically plummet.

Other options aren’t as definitive because tachycardia can occur in both conditions, stable vitals are unlikely in a tension pneumothorax, and chest pain isn’t a reliable distinguishing feature.