What is the hallmark finding of flail chest?

• A. Hyperresonance with crepitus
• B. Chest wall deformity only at rest
• C. Decreased breath sounds but normal movement
• D. Paradoxical chest movement during respiration

Answer: (D)

Paradoxical movement of a chest wall segment during respiration defines flail chest. When multiple ribs are fractured, the unstable segment moves inward on inspiration and outward on expiration, opposite to the rest of the chest. This abnormal motion prevents effective ventilation of the underlying lung, leading to increased work of breathing and potential hypoxemia. Other signs like hyperresonance with crepitus can indicate pneumothorax or subcutaneous emphysema, and a deformity visible only at rest doesn’t capture the dynamic instability characteristic of flail chest. Management centers on securing the airway and breathing, providing pain control, and stabilizing the chest wall; in severe cases, positive-pressure ventilation is used to splint the segment and re-expand the lung.