The nurse is assessing a client who sustained a blunt chest injury. Which would indicate to the nurse that the client is exhibiting a flail chest?

A. Inward displacement of a rib section during inspiration is correct because flail chest occurs when two or more adjacent ribs are fractured in two or more places, creating a free-floating segment of the chest wall. This segment moves paradoxically, meaning it moves inward during inspiration and outward during expiration, which is the hallmark sign of flail chest. This paradoxical motion impairs ventilation and can lead to respiratory compromise. B. Continuous outward bulging of a rib section throughout breathing is incorrect because flail chest is defined by paradoxical motion, not constant outward movement. Continuous outward bulging may suggest other chest wall deformities or localized swelling but is not diagnostic of flail chest. C. Shift of mediastinal structures to affected side during inspiration is incorrect because mediastinal shift occurs in tension pneumothorax, not flail chest. In tension pneumothorax, air accumulates in the pleural space, pushing the heart and mediastinum toward the unaffected side, compromising circulation. D. Deep, inspiratory stridor during inspiration is incorrect because stridor is an upper airway obstruction sign, not a characteristic of flail chest. Flail chest primarily affects ventilation mechanics and causes paradoxical chest wall movement rather than airway noise.