I've heard people say that a defibrillator being used on someone whose heart has a normal beat, like if they have a blocked throat and can't breathe, but still have a regular pulse. However, I have also heard that defibrillators only stop and restart the heart. Wouldn't people then suffer the same risk from defibrillators if their heart is functioning normally as if it were stopped?

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    Defibrillators shouldn't be used on people who have a functioning heart. Some defibrillators however, such as the ones found in shopping centers, can often detect whether the patients heart is beating or not. Therefore if you are unsure, it is ok to attach the defibrillator and it will alert you as to whether a shock is required or not. – Kenshin Jan 6 '13 at 13:12
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    I don't think it is a duplicate. The link is about using defibrillator on a flat lined person (no heart beat), but this question is about using a defibrillator on a living person with a normal rhythm. – Kenshin Jan 6 '13 at 17:01
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    This question is clearly NOT a duplicate. I vote to reopen. – Coomie Jan 8 '13 at 1:18
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    I can't make out what the claim is that we are being skeptical about. If the question is How do defibrillators works? it is off-topic. If the question is "Wouldn't using a defibrillator on a regular heartbeat be dangerous?", it is off-topic (unless there is a claim to the contrary). – Oddthinking Jan 10 '13 at 11:39
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    The things you have heard seem all incorrect to me. However, as Oddthinking wrote, you have not included a reference to a notable claim - of which you are skeptical – RedGrittyBrick Jan 10 '13 at 12:10

Depending on the type of the defibrillator. The Automated external defibrillator (AED) units that are commonly available in airports, railway stations, government agencies, shopping centers and other places with lots of people, these are not dangerous to apply. The principle is that these "to-be-used-by-non-professionals" devices are "clever": they detect the conditions of the victim, and apply the shock only when fibrillation is happening, and in coordination with the specific detected fibrillation waveform. This means that they cannot operate on dead bodies, or on people with normal cardiac activity. For more information on these see: http://en.wikipedia.org/wiki/Automated_external_defibrillator

This is not the case of the medical defibrillators that do not detect the victim's conditions and apply the shock as the medic orders. In this case, the assumption is that the medic is watching the electrocardiogram continuously and selecting the timing and parameters of intervention in a similar (but more flexible) way to what an AED unit does automatically.


I am no scientist, but have worked as an EMT for a year.

Using a manual defibrillator on a person with a healthy heart is very dangerous. Aside from burns and other effects of an electrical shock, it is very likely to stop the heartbeat or cause ventricular fibrillation.

In general, a defibrillator is not used to start a heart but to get it out of ventricular fibrillation by either stopping it or bringing it back to a regular pulse.

  • +1, Welcome to stack.exchange. Thankyou for your valuable contribution to my site. :D Please come again. – Kenshin Jan 10 '13 at 14:00
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    Welcome to Skeptics! Please provide some references to support your claims. – Oddthinking Jan 10 '13 at 14:06
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    BTW--The EMT I know has a big pile of reference books from his training. I believe that quotes from those books (with the appropriate bibliographic data) would be "authoritative refernces" within the meaning used on the site, though a good on-line source would be prefereable. The downvotes should cease (and hopefully be reverted) once references are supplied. – dmckee --- ex-moderator kitten Jan 10 '13 at 15:04
  • Thanks for your answer. However, I'm surprised by it. Is there a greater risk of the heart stopping if a person with a normal heart rate is exposed to a defibrillation than a person with a fibrillating heart? – DarkLightA Jan 10 '13 at 15:26
  • Good question DarkLightA. – Kenshin Jan 10 '13 at 15:37

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