Which condition results from air entering the pleural space after injury, causing pressure that shifts the mediastinum toward the uninjured lung and compresses the heart and great vessels?

• A. Tension Pneumothorax
• B. Hypovolemic Shock
• C. Non-Hemorrhagic Shock
• D. Cardiogenic Shock

Answer: (A)

This question tests recognition of tension pneumothorax, a life-threatening complication after chest injury. Air enters the pleural space and becomes trapped, causing the intrapleural pressure to rise quickly. This pressure collapse the injured lung and push the mediastinum toward the uninjured side. The shifting of the heart and great vessels compresses them and, importantly, reduces venous return to the heart, leading to a drop in cardiac output and shock.

Because the problem arises from trapped air under pressure rather than from lost blood or pump failure, the other conditions don’t fit. Hypovolemic shock results from inadequate blood volume, non-hemorrhagic shock is a general term for shock without visible bleeding, and cardiogenic shock comes from the heart's inability to pump effectively. Here, the key feature is air under pressure in the chest causing mediastinal shift and impaired venous return.