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Comment by ghostpepper | Hacker News Reader

They link a study where they polled people shortly after a family member was admitted to the ICU about the effectiveness of CPR.

My partner is a nurse, so I already knew that the odds of community-delivered CPR were about 10% (although now I'm curious how those odds change when an AED is available) and about the cracking of ribs.

I think what this article could've emphasized more is that more people should learn about and consider Advance Directives and DNR (do not resuscitate orders), particularly for patients who are nearing the end of their natural life.

As it reads now it seems to suggest that bystanders should not bother doing CPR in the community, which I think is incorrect and borderline dangerous advice.

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> (although now I'm curious how those odds change when an AED is available)

AEDs are fucking magical.

They even talk to you to tell you how to use them.

If the need arises, get the AED and get going.

Isn't an AED only useful for tachycardia? I'm case of drowning, heart attack, or most other causes of a stopped heart, it isn't useful, correct?

The AED does not restart hearts, it can't do that, the shock disrupts an abnormal rhythm, allowing the restart to potentially take place automatically. But if your heart has actually just outright stopped, you are basically dead.

Clinicians report as little as zero success for patients in asystole (ie their heart has plain stopped). Some studies report a little higher, but it's also possible those rates are mistaken diagnosis, ie you see a flat-looking ECG, you treat anyway, maybe 1% of patients survive - but maybe that 1% were actually not really in asystole.

If you have a heart attack, both an AED and CPR are inappropriate, your heart is still working it's just that the blood isn't going where it's needed. You need immediate medical treatment. While an actual cardiac arrest (which would warrant an AED and CPR) is much more likely during a heart attack, it is not inevitable and these treatments are not prophylactic. Meanwhile your focus needs to be on alerting other people to your problem, so that they can get you medical treatment, and if you do go into cardiac arrest they can perform CPR or use an AED once that becomes appropriate.

> you see a flat-looking ECG, you treat anyway, maybe 1% of patients survive - but maybe that 1% were actually not really in asystole.

Isn't that basically the no true Scotsman fallacy?

False positive paradox.

Maybe?

Sometimes, when our measurements differ from what we can explain with our understanding of the universe, that's because we didn't understand the universe properly. If you put the Sun in the middle, your model of the solar system is still weird nonsense with planets on their circular orbits needing to swing backwards or accelerate forwards for no reason - until you make the orbits ellipses instead and then it's almost like fucking clockwork.

But sometimes, you were just right, and the measurements were off a bit, and there was no real physical phenomenon, you were just bad at measuring.

So, maybe sometimes the human heart does actually stop, yet it can successfully be restarted and then carry on as normal, and the circumstances where this is true are just fairly uncommon and when people are peering very carefully at the results they never ran into one of these rare cases. I cannot rule that out.

> If you have a heart attack, both an AED and CPR are inappropriate

This is a phrase that's easy to interpret in a dangerously wrong way. Here's a clarification:

If you have a heart attack and are still alive and talking, both an AED and CPR are inappropriate.*

If you have a heart attack and die, then both an AED and CPR are very appropriate and might bring you back.

* And even in this case the emergency response medics will put AED electrodes on your chest so it will be ready to use in case you crash.

I think AEDs can also pace these days if it's brady (but not asystole)

I'm not aware of any AEDs that will pace. There are devices that can function as both an AED and an external pacer. Most cardiac monitors used in ambulances have an AED mode that can be used by EMTs, in addition to the more advanced features (transcutaneous pacing, cardioversion, manual defibrillation, etc). Those are the sort of thing a layperson is going to come across as an "AED" though.

Vtach and Vfib are the two shockable rhythms. Those are common in many medical emergencies. Just because the patient doesn't have a feelable pulse doesn't mean they have "flatlined" and don't have a shockable rhythm! You have to put the AED electrodes on their chest to be sure.

If the patient has truly flatlined (asystolic) then shocking them won't bring them back. That only works in the movies.

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