What is the immediate action if a casualty goes into cardiac arrest in the field?

• A. Check for responsiveness and signs of life
• B. Call for help and wait for EMS
• C. Administer high-flow oxygen only
• D. Initiate CPR immediately and apply an AED if available; minimize interruptions and evacuate as needed.

Answer: (D)

In field cardiac arrest, the priority is to restore circulation as quickly as possible through immediate high-quality CPR and defibrillation if an AED is available. Chest compressions keep blood flowing to the brain and heart, buying time while a shockable rhythm is identified and treated with defibrillation. Using the AED as soon as it’s ready increases the chance of a successful return of spontaneous circulation. Minimizing interruptions to chest compressions preserves perfusion and improves outcomes, so resume CPR immediately after any shock or device analysis. Evacuate for advanced care as needed, but don’t delay life-saving actions to move the casualty. Oxygen alone cannot restart the heart, and waiting to call for help or to administer oxygen would miss the critical early window for defibrillation and perfusion.