Automatic Internal Defribillators

[Guest]

Has anyone here ever run into an Automatic Internal Defibrillator in the field?

The reason I am asking is that I ran into one for the first time in the field recently and it raised a few questions. For one when it shocks, the pt convulsed quite violently and there is no wanring a shock is about to be delivered giving workers no chance to move out of the way of the victim. Also, I know when using an AED we always make sure everyone is clear before shocking for various precautions. That said if an Internal Defibrillator shocks while someone is in contact with the pt., could that create the very reasons that we clear before shocking with the AED??

Just curious thanks for any answers.

[Goose 188]

I've come across ICDs a number of times in the field. I've never seen the device in action, only been called because it fired. Those patients i have helped treat have, for the most part, said they anticipated the caridovert and have felt it go off with few complications. It's been described to me as a punch or kick in the chest which lasts a few minutes and thats about it. As far as convulsions go, i've never heard of those associated with ICDs, maybe its possible. I've also never heard of anyone being shocked by one due to their proximity or contact with the patient. The leads for an ICD are surgically (obviously) implanted strategically near the heart. To the best of my knowledge they utilize substantially less power than an AED does because of its placement. However, i don't know the exact joule measurement. When your using an AED your shooting 120J (depending on the model) back and forth across the persons chest in order to hit the SA and AV nodes, I imagine that by planting electrodes strategically you could get away with using less power while having a better result.

Edited July 4, 2007 by Goose

[Guest]

Goose, my pt. also described it as a punch or a kick in the chest but he said he felt no warning. And the device shocked him three times twice in my presence. Thanks for the answer.

[Goose 188]

Either way, the ER will be able to download what happened. But like i said, because the energy is so directed and low in intensity i can't see there being any harm.

Edited July 4, 2007 by Goose

[paratrooper75 41]

A lot less energy for internal defibs. No worries. The patient can sometimes tell when its coming. I couldn't imagine getting so use to v-tach that you know when its about to happen. Where external is around 120-200 J biphasic, I think internals are around 10-20 J.

[ny10570 745]

First time I had one go off on me was a few months ago in Manhattan. An elderly male called saying he was locked in a store with 20 other people, catch was he was alone with his wife in their apartment. He was caring for his demented wife and according to the door man he was usually A&O. So we can't get any history or info out of these two. Medic and I decided to just forget it and transport the two of them to what we think is their normal hospital. As we're going to get him ready to go he's walking across the the middle of the room and suddenly gets this shocked look on his face asking us why we shocked him. Take a quick look at his chest and see the battery pack so I take him by his arm to sit him down and bam we both caught it. On my end it felt like a poorly grounded light switch. Medic caught it too trying to hook-up the 12 lead. In the ED we were told a story of a guy who was getting shocked between 12 and 20 times a day. He refused medication or further surgery and decided to move to Brazil to die. Last the Doc heard the guy was still going after 2 years and still getting shocked, but more frequently.

[tbendick 27]

Had one some years back. Can't remember what the call came in as but the lady was sitting on the bed saying she didn't feel to good. She told me about the Defib and shortly after went into Cardiac Arrest, as I went to check a pulse the defib shocked both of us. She then began to talk again like nothing happened, it was kinda of strange.

The shock wasn't bad at all pretty much just makes you jump and say what the?

I would have to agree with the bad outlet/light switch feeling.

[Guest paramedico987]

Hmmm... I have to wonder of that guys leads were misplaced, 10570. The current should pass from one electode on one side of the heart to another on the other side and then back [they're all bi-phasic]. If you and your partner got shocked, something wasn't right. One aught to be able to be, theoretically, making out with someone when it goes off an not feel a thing. I suspec that the patient "convulsing" was just squirming cuz he just felt his heart nailed with a shock. And anybody that knows it's coming must just simply be used to what if feels like to be in VT/VF...

[Guest Orpi442]

I have had several. Yes a kick in the chest is how they have discribed it. One guy was use to it and actually rather deal with the tickel as he said then the pinch from the IV. A little lido and he would of been fine. As for being shocked while the defib fires, sorry to disappoint you, but no shock to the person touching the PT. The funniest was watching a EMT Sup pretty much throw the Pt onto the strecher a fraid she was going to get shocked. The reason is I DONT KNOW BUT YOU GOT ME THINKING. Let you know when I find out, unless someone else knows.

[Guest partyrock]

The current isn't going to just stay between the two electrodes. It radiates out along the path or paths of least resistance to ground. The few joules created by an internal pacer shouldn't be enough to pass through the skin, if the skin is wet, whats the resistance of the human body?

[Guest]

The current isn't going to just stay between the two electrodes. It radiates out along the path or paths of least resistance to ground. The few joules created by an internal pacer shouldn't be enough to pass through the skin, if the skin is wet, whats the resistance of the human body?

The impedance of a human is on the order of 1 MOhm, assuming the skin is intact (measured from one hand to the other). Also keep in mind that ground is just an arbitrary reference point (usually). I don't know the details of how these things work, but if it basically just creates a voltage between the two electrodes, the current would mainly travel between the two electrodes. Travelling from inside the body, through the skin to someone else would probably be a very high impedance path.

I have no idea what the internal impedance of a human is, but I'm assuming that since we're filled with an electrolyte that the internal resistance is pretty low.

[Guest paramedico987]

Jared is correct.

"Ground" is used when we are talking about, for the most part, standard household electricity. This is because we use the earth as one of the poles in alternating current. In this case touching the "hot" wire and the earth [or either of the other 2 wires in the outlet box connected to it] completes a circiut. [ note: the negative in a car is sometimes called ground also, even though the earth has nothing to do with that circiut]

With an ICD the circiut goes across the heart BECAUSE that's the path of least resistance within the body, between the two poles [aka electrodes]. The current IS seeking the negative pole [or ground if you must] but that ground is just on the other side of the heart, not the earth itself. This is also true of external defibrillation/cardioverson regarding "seeking ground" however in that circumstance there is the possibility that the current may circumvent the patient's skin [which has a higher resistance] partially and end up zapping you as it travells through oil/water/whatever that's on the pt's skin.

So unless the patient has some very strange [and by that I mean not compatible with life in the first place] anatomy, one shouldn't even be able to detect the shock from outside if the patient [or monitor if they're on it] doesn't indicate it to you.

[RescueKujo 130]

I witness one years ago, when I was driving our Children's Hospital Transport Team. We're in an ER and I hear this guy cussing up a storm. I think someone's going off on the staff, and start paying attention. I watch the staff lead a gentleman who's walking in an unusual way to a gurney. I ask a nurse what's up, she told me his AID was firing almost every 30 seconds. He'd take a couple of steps, it'd go off and you'd hear him yell. It looked like it hurt like hell.

Edited July 8, 2007 by RescueKujo

[Guest paramedico987]

Oh! FYI y'all if you've got them on the monitor and it's going off for no reason [i.e. they're not going into VT etc] you can turn it off by putting a magnet over it...

I know we don't carry magnets on the bus, but if you're at someone's house check the fridge for a strong one and it'll turn itself off without harming the device or patient.

[WAS967 97]

Oh! FYI y'all if you've got them on the monitor and it's going off for no reason [i.e. they're not going into VT etc] you can turn it off by putting a magnet over it...

I know we don't carry magnets on the bus, but if you're at someone's house check the fridge for a strong one and it'll turn itself off without harming the device or patient.

This actually does require a rather strong magnet so the typical fridge magnets won't work. You might see them in the ER stuck to a cabinet in the RN station....they are round blue and donut shaped and remind me a bottle opener. There is a technique for swiping the magnet over the device itself but I have never done it so can't state what it is.

Food for thought for the ALS providers - if you have a patient that tells you they were shocked by their ICD - would you give them antiarrhythmics enroute to the hospital? Why or why not?

Edited July 12, 2007 by WAS967