My question is, can you tell a person is in imminent danger of going into cardiac arrest just by feeling their pulse? In my scenario, the two characters have no advanced medical equipment at their disposal other than a stethoscope and a defibrillator which isn't there just yet (don't ask...). Anyway, Person B already is very weak and about to go into cardiac arrest. How would that manifest itself in the pulse? Would it be very very slow? Very irregular? No longer detectable, but the heart's still going? Would Person B be unconscious by then?
Once that happens, how long until the heart completely gives out? When would you start actually using a defibrillator, when would CPR be in order? I've read that even when you're using an AED (automated external defi) you still need to perform CPR between shocks. Also, realistically, how much time do you have after the first detection of fibrillation until there's permanent damage to be expected in the victim?
And while I'm at it, what on earth is the measuring unit they use for the defi? You know, when they set it to 250... 360... whatever. Is it volt? Somehow all the texts I've read assume you know that... Sorry, I'm kinda stupid in that aspect ;_;.