Which finding best indicates a flail chest?

• A. Absent breath sounds on the affected side
• B. Hyperresonant percussion on the affected side
• C. Paradoxical motion of the chest
• D. Tracheal deviation toward the unaffected side

Answer: (C)

The main finding here is paradoxical chest wall movement. When multiple adjacent ribs are fractured in several places, a segment of the chest wall becomes free to move independently. During inhalation, the rest of the chest expands while this segment moves inward, and during exhalation it moves outward, opposite to the surrounding chest. That opposite motion is what defines a flail chest.

This paradoxical movement impairs ventilation of the underlying lung, increases the work of breathing, and raises the risk of respiratory distress or failure. Patients may have chest wall pain and tenderness, and you might find crepitus over the fractured area, but the hallmark sign is the chest moving in the wrong direction with each breath rather than moving synchronously with the rest of the chest.

Other signs like absent breath sounds or a hyperresonant percussion note point more toward air leaks from a separate injury such as pneumothorax, and tracheal deviation suggests a tension pneumothorax or large mediastinal shift. Flail chest can occur with these injuries, but the defining feature remains the paradoxical movement of the chest wall segment. Management focuses on ensuring an airway and adequate oxygenation, providing analgesia, and often using positive-pressure ventilation to stabilize the chest and improve ventilation.