Hacker News Reader

Comment by softgrow | Hacker News Reader

The article is about internal defibrillators. External ones are still the same as (good grief) 35 years ago (well maybe down from 300J to 200J). The only change I've noticed is moving from a gel for the pads to a gel pad (which feel like a frog, chuck one in your partners bed and let them find it!) which reduced the possibility of burning and odd smells in your ambulance. Fortunately my sense of smell wasn't great and often had a partner who smoked (and was allowed to in the olden days) in the ambulance to dull it. You kids don't know how it was having to actually manually read the trace instead of all this new-fangled automation that guides you through it.

View on HN

As a former firefighter-paramedic of 14 years which I left in 2020, our LifePak monitors went up to 360J. We did use self adhesive pads and never once did I have any odd smells after "welding" someone. We used stacked sequence, starting out at 200J, 300J and 360J. Our LifePaks did have AED but very few people used that option, so yeah, medics and agencies still require to know how to read traces. To know which rhythms to shock and which ones not to isn't rocket science, nor are there that many. There are only two pulseless rhythms that get shocked. There are also a couple of reason to shock conscious people with rhythms that does require a bit more training and knowing when to give the shock but it isn't all that difficult to learn.

Not sure why the "us kids" comment. How come you aren't boasting about not wearing gloves and PPE? I've heard about "back in the day" how it was a badge of honor to be covered in someone else's blood. That shit ain't cool at all, but it does occasionally happen where blood does get on unprotected skin, it has happened to me.

Did we have to know as much as back in the 70s, 80s and 90s? No, not at all but that is advancement and not necessarily watering it down.

If I have an out-of-hospital emergency I definitely would want street medics and firefighter there for help. I am still shocked how often I've seen doctors and nurses loose their shit because they aren't use to having to think on their own or they don't have a team of 10 or 15 people there to back them up. I've seen it in firefighters and medics as well, just not as often. Most nurses aren't allowed intubate in a well lit hospital room, let alone lying on the asphalt of a highway or floor of someones home.

>Not sure why the "us kids" comment.

>Did we have to know as much as back in the 70s, 80s and 90s? No, not at all but that is advancement and not necessarily watering it down.

Sounds like you do understand the comment and agree with it, but still took offense.

Best of both worlds

Hi fm2606, I left ambulances in 1991. Probably was 1986 when we got Lifepack 5 (the first one that came in under $12000 AUD and totally manual, the lifepack 3 was in limited use from I think 1983 but way too expensive to have more than two for my city (1M people), cost was a real barrier). On introduction the only thing we had for conductivity was a gel. After a year or two the gel pads came out. The "us kids" was really a comment about my amazement at after more recently being trained in AED and the darn thing does everything for you. It has a whole lot of technologies that simply weren't available then (recognise rhythms, text to speech, record rhythms to storage etc etc). So much cheaper, lighter, don't need spare batteries, and seeing the huge change that technology has brought. (P.S. We were ignorant in the 80's. No gloves, no hard hats, had to wear ties and a fancy cap. No reflective wear except for bright yellow raincoats that we only wore to stay dry.)

> Did we have to know as much as back in the 70s, 80s and 90s? No, not at all but that is advancement and not necessarily watering it down.

We need to know much more now than ever before, as the number of treatments performed on scene has grown enormously. Not to mention survivability is orders of magnitude better.

AEDs are an amazing invention and I'm glad to see them dotted around the place. Initially in dedicated cabinets mounted to walls outdoors, and sometimes in repurposed telephone booths.

I see AEDs hanging on the wall at work. My only real thought is if I have a heart attack at work, just let me die. Clearly I'm not going to make it to retirement anyways if the stress nd stress eating from my job is giving me a heart attack.

Bit of a false dichotomy: some people survive a heart attack without intervention, but suffer crippling injuries as a result. It's entirely possible to develop arrhythmia, fall into a low-oxygen state where you get brain damage, and then have your stupid heart decide to start pumping again.

That's fine. At least I'll be too brain damaged to go back to that hell hole.

you could leave now...

Not really. I have a family to support and no real alternatives.

while I don't know the details of your situation. However, my experience says there's always an alternative. Sometimes it means networking yourself. Sometimes it means changing industries while still leveraging your skills. Sometimes it means getting some education/certifications (even at night). Good luck on your future.

"New defib placement increases chance of surviving heart attack by 264%" (2024) https://newatlas.com/medical/defibrillator-pads-anterior-pos... :

> 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.

"Initial Defibrillator Pad Position and Outcomes for Shockable Out-of-Hospital Cardiac Arrest" (2024) https://jamanetwork.com/journals/jamanetworkopen/fullarticle...

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.

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.

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).

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

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.

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 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)

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.

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.

I think the biggest change with external defibrillators has been placement. It's now front and back instead of two on the front.

I just did a training course and for the ones we used it was still two on the front. Only for children it's front and back.

Likewise in the UK, two on the front, at least for adults. Makes less disruption to CPR if you leave the patient on their back.

I should redo my CPR then. Learned two on the front in high school in NJ. But also to read the instructions though I'm sure when seconds count you don't.

Modern AEDs have voice guidance telling the person what to do. So you can follow the instructions as you do it.

Also, you should call the emergency number in your region and (at least in Australia) they'll transfer you to someone who can coach you through using the defib and performing CPR until professional help arrives.

Don't let that stop anyone from getting their CPR up to date though. The more experience you have the better equipped you'll be if you need to use it

I see AEDs at work. If I have a heart attack, I have no confidence in my team being able to use it. I've seen how they handle requirements and documentation in stories.

> Not sure if we have time for learning CPR in the current sprint, let's put it in the backlog

was going to say, you need to make sure to open a ticket and bring it to the refinement meeting.

Well I thought it was one in the front and one close to the ribs

> having to actually manually read the trace instead of all this new-fangled automation that guides you through it.

I never met a LifePak 12 that did not flag every 12 lead it saw as an "Abnormal ECG".

Zolls aren't any better. I managed a fleet of 70+ X-Series Advanced, and only read normal on young adults who were perfectly still and electrodes were placed perfectly. That being said, the rhythm and 12 lead interp algo on it was impressively accurate. It would very often pick up subtle very high lateral infarcts, usually only identified by clinicians familiar with the "south african flag sign."

Reply on news.ycombinator.com