Final answer:
The priority action by the nurse is to begin CPR.
Step-by-step explanation:
The priority action by the nurse is Option 1: Begin CPR. A respiratory rate of 8 BPM after administration of an opioid anesthesia indicates severe respiratory depression. This is a life-threatening situation, and immediate intervention is needed. The nurse should initiate CPR to provide artificial ventilation and circulation until advanced medical help arrives.