> Placing [AED,] defibrillator pads on the chest and back, rather than the usual method of putting two on the chest, increases the odds of surviving an out-of-hospital cardiac arrest by more than two-and-a-half times, according to a new study.
I know article authors don't write their own headlines, but for all who read this: it's about out-of-hospital cardiac arrest, which can be caused by a heart attack, but is in no way the most likely presentation of a heart attack.
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).
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.
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.
I teach AED use and both my curriculum and trainer AEDs have one pad on the right chest and one on the left side. Is this the “two on the chest” method? If so, why have organizations not updated their curriculum and tooling?
Should I assume that irrespective of this finding, pads should be placed where the AED indicates so that rhythm detection works correctly?
A lot of places have updated their curriculum or clinical guidance documents. Medicine is a slow moving beast, however, so change takes forever. A lot of AHA recommendations are woefully outdated. But everyone keeps doing the same thing because they are scared to not do what AHA recommends. I have 15 years as a medic, with 5 being as a training officer for a large capital city metro EMS system. Our clinical guidelines were probably updated 2017-18 with new placement guidance to start placing pads anterior-posterior. At first it was to facilitate automated CPR devices (Lucas) and CPR feedback puck placement. We noticed better resuscitation results, even when considering the CPR devices. Our medical director is extremely progressive and some short research later and consulting with Zoll, we moved to anterior posterior.
If you think of the traveling electrical power as a vector (pointing arrow), consider Anterior-Anterior vs Anterior-Posterior and draw a vector (arrow) between the pads. Which placement directs most of the power to the tissue of the heart? Anterior-Posterior does as the arrow goes directly through the ventricles, the area responsible for the VF/VT rhythm generation.
Once I learned how monitors, specifically Zoll, do rhythm analysis, and especially Zoll's Shock Conversion Estimator, I moved on and went back to school for engineering to help design products like these. It is all really cool stuff.