Building a DIY defibrillator in an emergency, - Page 1
Forum section: electronics / general

author: Psi
author_rank: Super Contributor
timestamp: April 24, 2020, 01:34:17 pm
content: Engineering thought experiment time....I've always wondered, how feasible is it to build a crude defibrillator in an emergency from random household electronics.Something that has at least some hope of restarting a heart.Scenario- You're an electronics engineer in a group of 3 including you. All are engineers,- You're in the middle of nowhere, 12 hours away from any help.- One of the people has a medical event and their heart goes into fibrillation- You and the other person take turns giving CPRCPR is very tiring, eventually you will both get too fatigued to continue.Even with 2 people taking turns you're not going to be able to do it for 12 hours.So, since the person is going to die before help arrives you both decide to rip apart any electronics available and try to build a crude defibrillator in the hope it might restart their heart. You decide to take turns building while the other does CPRAssumptions for this thought experiment.- There is 240V power at the location- There is a house and workshop with a good selection of common tools and equipment.Initial thoughts about some stuff you will likely have to work with- 330V DC available in any mains powered device that has a bridge rectifier.- You could easy hack together a voltage doubler to get 600V.- You could get 2kV from the microwave, but it only has around 1uF cap- The kitchen probably has some cooking utensils that have a large flat metal surface and insulated handles for electrodes.- aloe vera gel and salt can be used to make conductive gelUnknowns- How short of a pulse do you need to apply. Can you control it just by touching the electrodes to skin or does the timing have to be critical.I know modern defibrillators employ lots of advanced timing and pulse shaping to mimic the human heart response and be more effective. But all we are going for is the best we can do with what we have,

author: jogri
author_rank: Frequent Contributor
timestamp: April 24, 2020, 02:13:45 pm
content: QuoteIf that happens they are most certainly dead, defibrillation is only usefull when you have ventricular fibrillation (meaning that the heart muscle twitches really fast [up to ~12Hz] without moving blood). What a defibrillator does is apply a really nasty electric shock with ~300J energy that overpowers the chaos in the hope that the signal from the sinoatrial node (who is responsible for firing the heart muscles) can start a controlled stimulation of the heart muscles to get it to beat again.CPR (the pumping part) is just there to squeeze the heart manually and get the blood to circulate a bit to ensure that the brain doesn't run out off oxygen.A defibrillator uses a pulse in the 300J range at a few kV, so i'd start collecting capacitors (to store the energy) and making a crude voltage multiplier. I wouldn't worry about building some fancy pads, copper wires and a saline solution should suffice.Btw, chances are that you don't have the necessary manpower to build something with only two guys as they are both needed for the CPR: One has to pump while the other has to get air into the lungs, otherwise he is most definitely dead after ten minutes when the oxygen in his blood runs out.

author: Psi
author_rank: Super Contributor
timestamp: April 24, 2020, 02:23:19 pm
content: Quote from: jogri on April 24, 2020, 02:13:45 pmThanks, i think i knew that but had forgot. Have edited post.Quote from: jogri on April 24, 2020, 02:13:45 pmBreathing air into the lungs is no longer considered necessary for CPR. I'm not sure of the details but apparently the lung muscles do move a little while in ventricular fibrillation and you get enough oxygen to keep the brain alive with just chest compression.However, i'm not sure how well that works for hours on end. so yeah, might need extra person.

author: m98
author_rank: Frequent Contributor
timestamp: April 24, 2020, 03:05:59 pm
content: Uhm, since we are in a hypothetical scenario, you already somehow know he is in cardiac arrest and has a shockable rhythm ... punch him mildly hard exactly in the middle of the sternum immediately after he dropped, before starting any other measures.Don't do this in real life unless you exactly know what you're doing.QuoteBecause way too many people do it wrong, or won't even start CPR because they're disgusted. It will still vastly improve the outcome.The best measure in such a scenario would probably be to start the most optimal CPR you can manage (after establishing that he actually is in cardiac arrest), rotate positions every two minutes to get consistent and good compressions, and hope he eventually starts cursing you. There also wouldn't really be a point to perform CPR for more than an hour or two without any diagnostic equipment and medications available. You simply can't treat the condition that caused the cardiac arrest, and it most probably is also too late to do so at that point. Especially after 12 hours.

author: Psi
author_rank: Super Contributor
timestamp: April 24, 2020, 03:36:55 pm
content: Quote from: m98 on April 24, 2020, 03:05:59 pmWhat if the condition that caused it was an electric shock. So nothing really wrong with the person other than fibrillation ?

author: jogri
author_rank: Frequent Contributor
timestamp: April 24, 2020, 03:52:21 pm
content: Quote from: m98 on April 24, 2020, 03:05:59 pmYeah, the good old "accidentally inflating the stomach" trick... Not prettyQuoteChances are that you are just breaking off a part of his sternum, leading to him getting stabbed by his own bones every time you compress his chest while performing CPR. That punch is only effective when you already have an ECG hooked up and see him having a heart attack in realtime, but almost all ECGs used by emergency services have a built in defibrillator, so what's the point of punching him before you shock him?But back to the problem: I'd probably go for the microwave and add a few capacitors, together with a crude rectifier to maintain the voltage at the capacitors. Use an outlet with a switch, that way you can charge your caps by switching on the outlet and shock him while the outlet is off to avoid electrocuting him constantly.

author: m98
author_rank: Frequent Contributor
timestamp: April 24, 2020, 04:38:40 pm
content: Quote from: jogri on April 24, 2020, 03:52:21 pmQuote

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: April 26, 2020, 10:42:45 pm
content: Having performed thousands of CPRs on patients, I can tell you that if you do not have a shock available within maybe 15-30 min. It is futile.I am not sure of current recommendations as to when to stop. We almost always went longer.Defib machines use capacitor discharge and the output is measured in Joules. In v fib there is no timing of pulse.200 Joules is about 500 Volts charged into 2000 uF caps.The newer defibs are bi-phasic, I don't think we can make one fast enough.After all sorts of goofy recommendations, including "stairstep breathing", the CPR gurus found out that just pumping the chest circulates enough air. Not too fast, about one Hz, faster in children.Precordial chest thumps can work, but you must be careful not to break anything. I have seen it many times, usually in witnessed v tach in the ICU. Can work like magic.After too vigorous CPR, the rib fractures and dislocations will make CPR ineffective. You need an intact chest for CPR to work.Without an ECG you do not know if there is any activity in the heart at all. You do not know if the individual is in V fib. You shock anyway when in doubt.That's all you can do. If there is not electrical activity in the heart, shock will not help, but we try anyway. Maybe the V fib is so fine it is not visible on the ECG machine.There are asystolic conditions (no electrical heart activity) that respond to pacing either internal or external.If nothing else was available I would charge up some big capacitors and connect them across the chest. Whatever you have. MacGiver it. Maybe 400-1000 volts.At this point it cannot hurt

author: SiliconWizard
author_rank: Super Contributor
timestamp: April 26, 2020, 11:04:21 pm
content: Quote from: Wallace Gasiewicz on April 26, 2020, 10:42:45 pmHave you ever done that? Shock while having no ECG? (And if so, has it ever succeeded?)

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: April 26, 2020, 11:56:32 pm
content: The first cardioverter I used was an electron tube type machine with a CRT. It took a while to warm up. Was about two foot cube. Weighed maybe 100#The ECG leads were separate from the paddles. Sometimes they fell off. Also took a while for the CRT tube trace to return. I was an orderly back then. The doctors would shock anyway. No pulse etc...Newer cardioverters have the leads in the paddles but sometimes there is not a good connection because of sweat, dirt or whatever. Makes a real messy trace. Unusable.If you are not sure, shock, that is the only thing that can save the person. This has happened and can work.Do I ever recall shocking someone in asystole who recovered? No. I cannot remember this ever working.We were talking about a MacGyver approach without access to an ECG machine. I have never tried this at home.

author: SilverSolder
author_rank: Super Contributor
timestamp: April 27, 2020, 02:41:07 pm
content: Quote from: Wallace Gasiewicz on April 26, 2020, 10:42:45 pm60 times per second? - typo?

author: SiliconWizard
author_rank: Super Contributor
timestamp: April 27, 2020, 02:50:55 pm
content: Quote from: SilverSolder on April 27, 2020, 02:41:07 pmSurely that's more like 60 per minute.Otherwise - not only are they talking about McGyver defibrillators here, but CPR at 60 Hz, maybe you'd do that with some big vibrator directly connected to mains.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: April 27, 2020, 10:08:33 pm
content: Yea one Hz, sorry.Yea vibrating... thanks for correcting me.. but this brings up another strange memory. At one time there were respirators proposed that worked at vibrating frequencies, these, as far as I know, were for use in NICUs. I do not think that any of them were actually made for use but there were studies on animals. Supposedly they were for use in NICUs and were less apt to cause ventilator related lung damage. Supposedly "vibrated" the air in the lungs to mix incoming air with air in aveoli.

author: SilverSolder
author_rank: Super Contributor
timestamp: April 27, 2020, 10:38:26 pm
content: Interesting idea (vibrating the air in the lungs) - maybe it promotes the interchange of gases between the blood and the air, making better use of whatever air is there?

author: Psi
author_rank: Super Contributor
timestamp: April 28, 2020, 10:58:48 am
content: Quote from: Wallace Gasiewicz on April 26, 2020, 10:42:45 pmThanks! Some good info there,Especially interesting that you only have 30min or so to get any DIY solution implemented.2000uF at 500V is rather large and might make it unfeasible right there, that's not going to be easy to find in random household devices.Anyone got ideas on how to build a 2000uF cap using commonly available devices? Even 1000uF would be hard

author: NiHaoMike
author_rank: Super Contributor
timestamp: April 28, 2020, 01:40:28 pm
content: Quote from: Psi on April 28, 2020, 10:58:48 amOnly have to take apart a few PC power supplies to get enough caps.I would go for the microwave oven transformer and connect AC power for a split second by swiping two wires together. Very easy to put together on short notice.

author: G7PSK
author_rank: Super Contributor
timestamp: April 28, 2020, 09:00:19 pm
content: https://youtu.be/FnAOmxnQJsM<iframe width="1280" height="720" src="https://www.youtube.com/embed/FnAOmxnQJsM" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

author: SiliconWizard
author_rank: Super Contributor
timestamp: April 28, 2020, 11:10:34 pm
content: Ahah, I remember this Mr. Bean episode.

author: tpowell1830
author_rank: Frequent Contributor
timestamp: April 29, 2020, 09:05:26 pm
content: A very interesting proposition with some interesting responses.Having worked at an industry leading company that made implantable defibrillators, I have to say that there is no way that you can be sure that fibrillation is the cause of the patient's "medical event" without observing the heart rhythm with special instruments. All of the defib units that I have seen, whether a portable external unit or an implanted unit, has circuitry and software to detect that fibrillation is in progress. All of the units that I have seen also work automatically and will give a specific joule output to the attachment pads. Unless the group of engineers has instruments that can detect heart rhythm, they cannot know that fibrillation is present, and shocking someone is a bad idea. The reason to shock is to completely stop the heart activity so that the body will sense and restart natural sinus rhythm. The defib units, after giving a specific joule output will start monitoring the heart rhythm and will up the joule output and give another shock if the heart is still in fibrillation and repeat until a natural rhythm is detected. I think most units have a specific number of times that it will shock and then will stop further attempts.With that said, if there were adequate pieces of electronics around and an oscilloscope, it could be possible to monitor and then defib, perhaps with 10-20% chance of success, which if I were the patient, that is 10-20% more chance than sitting around and waiting for help to arrive, because the longer the heart is in fibrillation , the less chance of brain survival that you have. With someone doing chest pumps, while others are trying their very best, the patient has a better chance.Just my 2 cents...

author: JohanH
author_rank: Frequent Contributor
timestamp: September 25, 2023, 03:55:45 pm
content: Quote from: Psi on April 28, 2020, 10:58:48 amI thought everyone had them in a box somewhere...

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: September 25, 2023, 10:45:45 pm
content: Someone brought this thread back to life.I do have a MacGiver defibrillator in the house, I just did not realize it ....How about 700V on the plates of a 100 watt amplifier? Like the old Yeasu 101 or the Kenwood 520 or even the old Drakes and Hallicrafter radios?Probably enough juice, just be careful to zap with the DC and not with transmit turned on.Certainly this is not a common household device, but some of you have one.Or even the volts on the old CRTs although this is very high voltage.By the way, I am not advocating anyone actually try this.

author: amyk
author_rank: Super Contributor
timestamp: September 26, 2023, 12:32:47 am
content: Quote from: Wallace Gasiewicz on September 25, 2023, 10:45:45 pmPun intended?mikeselectricstuff has a few defibrillator teardowns on his channel. I remember one had schematics too.

author: Andy Chee
author_rank: Super Contributor
timestamp: September 26, 2023, 03:34:21 am
content: Instead of a defibrillator, perhaps a chest compression machine would be an easier contraption to build?

author: SiliconWizard
author_rank: Super Contributor
timestamp: September 26, 2023, 03:57:52 am
content: Quote from: Andy Chee on September 26, 2023, 03:34:21 amIn sincerely doubt it.

author: tautech
author_rank: Super Contributor
timestamp: September 26, 2023, 08:29:42 am
content: Quote from: tpowell1830 on April 29, 2020, 09:05:26 pmLike an oscilloscope ?Wonder where an EE would find one of those.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: September 26, 2023, 11:31:52 am
content: Just an oscilloscope does not work. We need to get rid of the RF and especially 60Hz interference we have today. You need a front end that will get rid of the common mode problems and amplify the ECG signal at the same time.There are DIY pretty simple units that do this. Even Google thinks so. But you need something else besides a scope.Also the ECG lead connections are important to minimize any galvanic effects on the skin. , while making good connections.Silver plated leads were used when I first did an ECG along with special conductive paste, now the disposable leads contain the silver and the conductive paste (gel)By the way EKG is the German of ECG.https://www.nutsvolts.com/magazine/article/February2017_Build-ECG-EKG-Unit

author: Psi
author_rank: Super Contributor
timestamp: September 27, 2023, 08:33:26 am
content: yeah, using an oscilloscope to look at your heartbeat isn't as easy as it seems like it should be.I've tried.

author: AVGresponding
author_rank: Super Contributor
timestamp: September 27, 2023, 05:00:03 pm
content: By the time you've built your ad hoc defib it'll be too late to be of any use.Far better to use a website like thishttps://www.defibfinder.uk/, or download an app to your smartphone.

author: janoc
author_rank: Super Contributor
timestamp: September 27, 2023, 07:19:06 pm
content: Quote from: AVGresponding on September 27, 2023, 05:00:03 pmAn even better idea is to learn how to administer CPR and actually perform it, while having someone call the emergency services. Thinking about building anything or searching for a defibrillator on a phone when you have a victim on the floor in cardiac arrest is ... bonkers?We are talking about minutes that person will survive without immediate help, tops. CPR might not save them either - but if you spend that time looking for gadgets and/or McGyvering something instead of working their chest, they will die for sure.Something I was taught by an ER doctor - don't worry about breaking ribs or catching something because of mouth-to-mouth breathing. Both will heal but nobody can cure death. The goal is to keep the victim alive while help arrives. Also nobody can successfully sue you for breaking their ribs (or causing other injury) while you were saving their life. OTOH, in many places you can be criminally prosecuted for not helping despite being able to.

author: Psi
author_rank: Super Contributor
timestamp: September 27, 2023, 08:46:09 pm
content: Quote from: janoc on September 27, 2023, 07:19:06 pmYou're forgetting the original scenario in this thread.There's another person able to give CPR, there's no hope of getting any help within 12 hours due to your location.So you might as well try and build something to shock the person. You don't have much time, maybe 20-30min, but that might be long enough to smash apart some devices and add extra caps onto one of them to make 325V DC with some energy behind it. (probably only going to work in 230VAC countries, 110VAC would need voltage doublers and that is getting to complicated)Even if both of you are fully trained in CPR, you still need the defibrillator within the 20-30 min

author: tautech
author_rank: Super Contributor
timestamp: September 28, 2023, 03:33:09 am
content: Quote from: Psi on September 27, 2023, 08:33:26 amHow hard ?It need be a differential measurement and skin conductivity needs be improved.Got any conductive zinc based heatsink compound ?I do have a stash of used ECG pads saved from a few days in a Cardiac ward especially to have a play around scoping with but as yet not had the chance and these do have a connection nipple that a probe hook could attach to.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: September 28, 2023, 02:05:08 pm
content: You really do not need timing in V Fib,you just shockYou assume there is no discernible rhythm because that is the most likely scenario.In cardiac arrest the rhythm, if there is any, will degenerate to v fib.This is absolutely true:Quote

author: janoc
author_rank: Super Contributor
timestamp: September 28, 2023, 09:20:14 pm
content: Quote from: Psi on September 27, 2023, 08:46:09 pmEven in that scenario you are more likely to kill the person with your gadget than to help. Moreover, you would do better helping or swapping with the person administering the CPR so that they can rest because it is very exhausting, esp. if you are doing both cardiac massage and breathing at once and alone.Also, don't forget that if victim doesn't get help for whatever caused them to keel over in the first place, you can CPR/shock them as much as you want, theywilldie - and much faster than in those 12 hours. If they are having a heart attack this serious, they are certainly not going to survive without immediate medical attention, regardless of whether you shock them or just keep doing CPR for hours. That vein blockage won't clear itself even if you stop the fibrillation.And that assumes you are 100% sure they have a heart attack - a person can suddenly keel over and have no pulse for various reasons, which you can't determine as a layman by merely looking at them.The defibrillator helps only in one specific situation, which is the reason why the units intended to be used by laymen always have a built-in diagnostics that will not let you shock the patient when the conditions are not met - you could kill them! It is not a magic "save life" button.You are solving a non-existent/completely wrong problem.

author: SiliconWizard
author_rank: Super Contributor
timestamp: September 28, 2023, 09:30:22 pm
content: Agreed, that would also assume that you have the required parts lying around where you are, but no access to an emergency service. Yeah. Maybe if you live in Antarctica or something and have lab equipment because you are on scientific program. In which case, you'll probably have commercial defibrillators with you anyway. It's probably more a rhetorical question than anything else.Also note that if the person dies after you have administered your DIY shocks, you will probably be under investigation and may end up in jail. (Unless again it can be proven that you had absolutely no access to any kind of medical help whatsoever.) Just saying. Don't do it.

author: Halcyon
author_rank: Unknown
timestamp: September 29, 2023, 01:40:00 am
content: Quote from: Psi on April 24, 2020, 02:23:19 pmEmergency services are trained in rescue breaths however they are entirely optional. There are cases where the first responder is unable or unwilling to give rescue breaths and that is perfectly fine (and won't expose you to any litigation if you simply refuse). After 30 chest compressions, 2 rescue breaths is still the recommendation. Rinse and repeat. If rescue breaths are not given, by compressing the chest cavity, you are still causing some air to enter and be expelled from the lungs anyway. If you don't know what you're doing, just stick with compressions (they should be deep enough where you might break ribs).In relation to the OPs question, my (basic) understanding is that AEDs (Automated external defibrillators) are only effective if the heart muscle in a particular state of tachycardia or fibrillation. After a series of compressions, the AED will instruct the first aider not to touch the patient while it measures what the heart is doing. If it detects that neither condition exists (or if the heart has stopped entirely), a shock will not be delivered.Manual defibrillators (such as those you see in Ambulances and hospitals) will allow shocks to be delivered in a wider range of circumstances, but are more complicated to operate and require proper training to be effective.As for the shock that is delivered from the AED itself, they will deliver a shock with a biphasic waveform, I guess similar to AC. The first phase of the shock is generally <=10 milliseconds in duration.In any case, if chest compressions can be started early and maintained until emergency services arrive, I would say the patient has a far better chance of survival as opposed to attempting any kind of home-brew defibrillation which might put the heart in a state where an AED could be rendered ineffective. If you render first aid as per your training, you won't/can't be sued for negligence even if the patient dies. If you start messing around with mains power and the patient dies, that could be on you. The other consideration is that in a panic and in the heat of the moment, you might be exposing others or yourself to unnecessary danger.

author: Psi
author_rank: Super Contributor
timestamp: September 29, 2023, 01:56:27 am
content: As a last resort, after CPR has been given for 30min, you might as well try and shock them.At that point they are dead anyway and you have nothing left to lose.Given that help is 12 hours away and both the people are now too exhausted from CPR to continue and continuing after 30 min is pointless anyway.)No one is suggesting a DIY defibrillator is a good idea, except as a last resort before giving up.The thread was only an engineering thought experiment.

author: SiliconWizard
author_rank: Super Contributor
timestamp: September 29, 2023, 01:58:43 am
content: If you are concerned about that case possibly happening and have had ample time to think about it, just buy an AED and put it in a safe, yet accessible place.

author: Psi
author_rank: Super Contributor
timestamp: September 29, 2023, 02:00:13 am
content: Quote from: SiliconWizard on September 29, 2023, 01:58:43 am'Absolutely agree.But this thread was an engineering thought experiment on building one when you don't have one.You can all rest easy that I have no desire, or need, to build one 'just in case'.For any situation with knowledge ahead of time that one might be needed it would be moronic to build it when you can buy a proper one.

author: SiliconWizard
author_rank: Super Contributor
timestamp: September 29, 2023, 02:17:17 am
content: I think our words of caution were more aimed at random people possibly reading this thread rather than you in particular. In public forums, you never know who's gonna read what. (And now, what is going to end up in a AI model.)Anyway, technically speaking - and not meant as advertising for AD, but purely to give some ideas about how an AED is designed, you can have a look at this:https://www.analog.com/media/cn/technical-documentation/apm-pdf/adi-aed-solutions_en.pdfAnd otherwise this:https://www.sciencedirect.com/science/article/pii/S2468067217300354

author: NiHaoMike
author_rank: Super Contributor
timestamp: September 29, 2023, 04:38:17 am
content: What about the case where one is trying to save a pet rather than a person? That might make things easier as the smaller size means a lower voltage.

author: AVGresponding
author_rank: Super Contributor
timestamp: September 29, 2023, 05:20:49 am
content: Quote from: janoc on September 27, 2023, 07:19:06 pmOh FFS do I have to explicitly state the implied context? Of course this is in ADDITION to performing first aid, which would include CPR, when and where appropriate, after ensuring there is no danger extant to yourself or the patient.Where I work, first aid courses are mandatory, with regular refresher courses.FWIW you can't be prosecuted for either trying to help or not trying to help, in the UK.

author: SiliconWizard
author_rank: Super Contributor
timestamp: September 29, 2023, 05:44:49 am
content: Quote from: AVGresponding on September 29, 2023, 05:20:49 amReally? In some cases, "not trying to help" is akin to failing your "duty to rescue", which I guess varies from country to country in terms of the law, but isn't there something like this in the UK? That would be interesting.Of course, the duty to rescue doesn't mean trying to do medical acts that you don't master at all on someone, if that's what you meant by "help". I guess the minimum you'd be expected to do when witnessing that someone has suffered a cardiac arrest would be to call the emergency services. If you can't, that would be trying to find help another way, as much as you can. No one's gonna expect from you than you'll save someone with a magical act that you have no clue about, unless it's actually your job.Conversely, doing something provably dumb or excessively risky considering the circumstances, especially if you are aware of the risks (say you are an engineer, you're supposed to know what kind of risks you'd take here by making a DIY defibrillator or something like that), I have a hard time believing it won't get you to being prosecuted and facing court.Would be interested in hearing more about the UK's law, and if indeed you'd never be prosecuted from trying something really stupid and dangerous to help someone. That would look like a can of worms if that were really the case.

author: AVGresponding
author_rank: Super Contributor
timestamp: September 29, 2023, 01:28:34 pm
content: I probably should have said "won't" instead of "can't", but in practice, it just doesn't happen.My guess is if you made a DIY defibrillator and the patient died after you used it, there's a definite possibility of prosecution, depending quite a bit on the findings of the Coroner.

author: SiliconWizard
author_rank: Super Contributor
timestamp: September 29, 2023, 08:39:13 pm
content: Quote from: AVGresponding on September 29, 2023, 01:28:34 pmYeah, now from a legal POV, that's still an interesting point I think - from what I have read in the meantime (nothing deep so far though), there indeed doesn't seem to be anything like a formal "duty to rescue" in UK's law, while there is in some other countries. But someone more knowledgeable in UK's law system can possibly correct this or add some precisions.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: September 29, 2023, 11:02:15 pm
content: In response to Halcion:You are essentially correct, in my opinion.In addition the quality of the "shock" delivered has changed with technology improvements and medical observations of the type of shock effect experimentally in laboratory animals.There is no way to quickly develop a modern "shock" that is delivered by current defibrillators.I suppose the first defibrillator that I used would be considered quite unsatisfactory in today's world. This was more than 50 yrs ago.In addition there are differing opinions as to when to terminate unsuccessful CPR.This is an ongoing argument. More than 30 min?The other thing to consider is how quickly is a defibrillator likely to arrive on the scene. The sooner the better.The silliest thing I have repeatedly seen in Movies and TV shows in the past is the application of a common AC wall outlet jolt to a victim. This is likely to produce more trouble than it can possibly alleviate.

author: SiliconWizard
author_rank: Super Contributor
timestamp: September 29, 2023, 11:10:23 pm
content: Quote from: Wallace Gasiewicz on September 29, 2023, 11:02:15 pmMr. Bean illustrates it brilliantly by making a parody of this.

author: johansen
author_rank: Super Contributor
timestamp: September 30, 2023, 03:32:07 am
content: Is it 2000v or 300v needed to dump enough current?4kv from a fully charged microwave oven cap is 4 to 8 joules assuming you can ensure you dont make a 500ma constant current source that does more than you want it to. The internal 10M ohm bleeder resistor means you have half a second to apply the pads or you lose half the charge.340 from a dumb pwrsup or 400 volts from a pfc corrected supply is probably a bad idea

author: antenna
author_rank: Frequent Contributor
timestamp: September 30, 2023, 04:53:32 am
content: CPR will not correct fibrilation (afaik), but the Modified Valsalva Maneuver might. By sitting up with legs extended and blowing into something to increase chest pressure, blood is forced out of the heart. After 10 seconds of this, you lay the patient on their back quickly while riasing their legs in the air. That causes the blood to rush back in and the pressure stimulates a nerve (in the aorta i believe) and resets the heart rhythm. It has a high sucess rate for SVT but, but from my understanding, only about 50% sucess for vfib. I have SVT, which for those that dont know is terrifying, and that trick fixed it twice. Scary sensation though, both SVT and when the Valsalva maneuver corrects it.

author: AVGresponding
author_rank: Super Contributor
timestamp: September 30, 2023, 06:46:08 am
content: My point about finding an actual defib machine rather than trying to ghetto-fab one, is that a proper one will give you verbal instructions on how to use it, and knows whether and when to deliver a shock. You just can't know if a patient is in VF or the heart is stopped unless you're a medical professional with the correct tools. It's pretty easy to miss a weak pulse, even if you're a medical professional without tools, and giving a shock to someone in that situation is going to kill them.There are lots of these things in public places nowadays, in the UK anyway, and the number keeps going up.https://www.nddb.uk/In short, go do a PROPER first aid course, and get a defib locator app on your phone. If you work in or near a public building in the UK, there will be one nearby; take the time to learn where it is.