Dunno why this is on my mind, but it is, and I can't stop thinking about it until I type this up, so.
There are a lot of guides out there on what to do in case of someone suddenly experiencing cardiac arrest. Please study https://www.stlukeshealth.org/resources/plan-it-cardiac-arrest-how-respond right now. It is short.
This guide, like almost all guides, omits the actual "crisis management" parts. Which is fine; teaching someone what to do and asking them to do it is the most approachable way to get the information out there. However, about half of people who collapse of cardiac arrest in public receive no help. Most people know they should at least call 911 (or your local emergency services shortcode), but don't, because they are confused and afraid and don't know who should do what.
It does not matter who does what as long as all the steps are performed as quickly as possible. You will decide who does what and you will do it immediately because it does not matter what the decision is but it does matter that the decision is made, and nobody without this specific crisis training starts yelling orders at complete strangers, which is the correct thing to do because then people do things instead of stand around alarmed and confused.
* Act. If someone suddenly collapses, YOU intervene immediately. Inaction kills.
* A person who cannot breathe and has no clear pulse is dead. You are reviving a dead person. It is impossible to hurt a dead person. Correct action will probably crush their ribcage. Inaction will guarantee they stay dead. I will refer to the person who has collapsed as "the dead person" as a reminder that your emergency response will not make their situation any worse.
* Direct. If nobody is already yelling orders, you will. Order individuals around: nobody responds to "somebody" because nobody knows who "somebody" is. If anyone you give an order to does not respond after two attempts, pick someone else. Give them a third attempt in case of "What?", but not a fourth if they stay confused and immobile.
At the top of your lungs, towards the largest group of people in the area who are not already involved: "CPR! CPR NOW! EMERGENCY! CPR NEEDED NOW!"
Yell "YOU! HERE! CPR!" at the physically most imposing person who responded. If nobody responds, start chest compressions and yell "YOU! HERE! DO THIS!" at the physically most imposing person around. Demonstrate chest compressions and emphasize: "All your weight. Do not stop. Break ribs." If you have the most upper body weight among people who can move freely, perform chest compressions yourself.
You cannot hurt a dead person. If you are not breaking ribs, your chest compressions are likely not effective. "Alive with shattered ribs" is much better off than "dead".
Yell at any one person not already using their phone: "YOU! CALL 911!" (non-Americans, replace with your local emergency number.) This may be redundant, which is fine, multiple 911 calls are much better than none. People texting, photographing, or recording video are preoccupied, it is not worth your time to try to get through to them.
If you know where an AED is: At anyone who looks like they can read signs and run quickly: "YOU! GET THE AED! RUN!" Point at the nearest "AED" sign. This may get a "What?", to which the answer is "There is an automatic defibrilator near that 'AED' sign. Get it! RUN!"
If you cannot get anyone to run for the AED in two tries, or you know where the AED is but the sign is around a corner, get it yourself. Run. Yell "MOVE! EMERGENCY!" at anyone in or almost in your path.
Use the AED. It will give you directions. If someone else got the AED and begins to use it, do not interfere.
Continue following AED directions (which will include when to resume chest compressions) until emergency services arrive. If whoever is performing chest compressions gets tired, find someone else.
* If an AED is close by and the dead person looks like an adult, use the AED before any other steps. Be conspicuous and loud and order a bystander to call 911. Adolescents and children need chest compressions for at least one minute before using an AED.
* The AED has sensors to determine what it should do. It will not deliver an electric shock to the dead person unless it might help. Do not be afraid to use an AED: it won't do anything if it doesn't need to.
* If you do not know where an AED is, yell "FIND AN AED" at nobody in particular. If someone knows what an AED is, this should start them running. Regardless, start picking random people who look like good runners: "YOU! FIND AN AED." You'll probably have to clarify: "Look for a sign that says AED. It has a picture of a heart with a pulse on it. It is probably over a doorway and probably near a bathroom. An AED is a defibrilator and it is this person's best chance to live. GO!" Then point in the direction of where you think the nearest bathroom might be. Repeat, sending people in different directions.
* If someone else is yelling orders at strangers, let them. If you know where the AED is, yell "GETTING THE AED" and sprint for it. You will save time. Time saves lives. Otherwise, if you know CPR, push your way to the dead person and start. If someone smaller than you is doing chest compressions, interrupt them with "I can push harder" unless the sound of breaking ribs informs you that they are doing well enough.
* You will probably fail. Even with the best possible bystander response, with an AED immediately available, most dead people stay dead. 40% of people who experience cardiac arrest in public and receive bystander intervention survive. Without intervention, less than 5% survive.
* About half of people who die of cardiac arrest in public receive no help from bystanders. 35% of these people were killed by the inaction of bystanders.
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