[westurner]

The AED should measure the rhythms before applying defibrillation.

An emergency AED operator doesn't need to make that distinction (doesn't need to differentially diagnose a HA as a CA) , do they?

You just put the AED pads on the patient and push the button if they're having a heart attack.

[devilbunny]

You put the pads on anyone who suddenly passes out and let the AED decide.

It will recognize ventricular fibrillation (the most common fatal arrhythmia). Technically, you don't shock pulsatile ventricular tachycardia, only pulseless. Not sure how AED's handle that, as I'm an anesthesiologist and would not use one at work - I'd read the rhythm myself and detect pulse either manually or with, say, a pulse oximeter. Never had cause to use an AED out in public.

Plain old CPR is what you do if they have pulseless electrical activity (the electrical system of the heart is working, but it's not pumping blood) or complete cessation of electrical activity (though it's probably not going to work in that case). We can use manual defibrillators as external pacemakers (much lower power output but still not going to be fun).

[westurner]

(and stand clear such that you are not a conductor to the ground or between the pads)

[devilbunny]

Grounding isn't an issue, as AED's are battery-powered once they are pulled off the wall.

But they do pump out a lot of juice. If you're touching the patient, it will HURT.

[westurner]

One can certainly shock onesself with a battery-powered car starter jump pack, particularly if one is a conductor to the ground or the circuit connects through the heart (which it sounds like anterior-posterior helps with).

Potential Energy charge in a battery wants to return to the ground just the same.

[devilbunny]

Oh, yeah, you can shock yourself very hard. But between two battery contacts, there is no ground. You can touch either one with no problem. It's when you touch both that you get the blast.

There's no return circuit even with your feet in salt water if you touch only one post of a battery.

[westurner]

I don't think that electron identity is relevant to whether there's e.g. arc discharge between + and - charges of sufficient strength?

Connecting just 1.5V AA battery contacts with steel wool causes fire. But doesn't just connecting the positive terminal of a battery to the ground result in current, regardless of the negative terminal of the battery?

(FWIU that's basically why we're advised to wear a grounding strap when operating on electronics with or without discharged capacitors)

[devilbunny]

Grounding straps prevent static charges from building up on you. A battery doesn’t really have a ground. The body of cars is hooked to the negative pole of the battery, so it’s called the “ground” of the car, but that’s for corrosion reasons.