If an unresponsive victim is not breathing or only gasping, what should be the first aid response?

Assess. In an adult victim following bls/acls protocol you want to assess and call for help *911 since getting AED or other medical help is imperative when it cardiac cause. Want to make sure that the patient's airway is open and not blocked but in victim unresponsive you may not know enough about any neck trauma. Start CPR if no pulse, chest compressions 100x a minute. There is protocol.