Final answer:
A nurse should prioritize pain management by administering IV opioids for pain relief for a client with a flail chest to facilitate better breathing and prevent pulmonary complications.
Step-by-step explanation:
A nurse in an emergency department caring for a client with a flail chest should prioritize maintaining the patient's ability to breathe while managing pain. A flail chest occurs when a segment of the rib cage breaks and becomes detached from the rest of the chest wall, leading to potential respiratory insufficiency. The correct action out of the provided options is C. Administer IV opioids for pain relief. This is because effective pain management can help the patient take deeper breaths and reduce the risk of pulmonary complications, like pneumonia. Applying a bulky dressing (option B) is not recommended as it may restrict chest wall movement. A bronchodilator (option A) would not address the structural problem of the chest wall, and while encouraging deep breathing exercises (option D) is important, it should be done after adequate pain management.