[FireBeyond]

> Many modern AED's can be used by untrained people, so if you see a cardiac arrest, find the nearest AED and deliver it and/or follow its (brief) instructions.

AEDs are specifically designed to be used by untrained people.

Don't bother doing anything with ventilation unless it's a pediatric patient who arrested specifically because of an airway issue (foreign body, near-drowning). We (EMS) will ventilate with high flow oxygen and intubate on our arrival, but even for us, it still comes a distant second to compressions and electricity.

With adults, blood can remain sufficiently oxygenated for cellular respiration/metabolism for about 8 minutes of compressions. Survival rates for adult CPR as a rough average go down about 10% for every minute of compressions required.