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Use of defibrillator

bignickel

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bignickel
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Perhaps I may be woefully unknowledgable about medical matters, but I thought that using a defibrillator on someone's who's heart had stopped was the last thing you'd want to do, unless you want to be sure to kill the patient.

I thought the defibrillator was used on patients who's hearts were beating extremely irregularly, and that it was a shot of andrenaline that was the procedure needed to start a still heart.

Any medical people out there?

http://www.nitcentral.com/oddsends/defibril.htm
 
You use a defibrillator to reset a heart that is fibrillating. A fibrillating heart chamber isn't completely stopped, but it is completely nonfunctional. You can survive if you have fibrillation of your atria (Bill Bradley has atrial fibrillation, and astronaut Deke Slayton was grounded because of it), but ventricular fibrillation is another matter. If your ventricles don't pump blood correctly, you die. Quick. (A rule of thumb is that you lose ten percent of your chance for recovery for every minute that your heart is off-line.)

When a heart fibrillates, it doesn't beat. It jiggles or flutters. It lacks coordinated pumping action.

Fibrillation is largely an electrical problem. Electrical signals propagate along heart tissue to cause the heart to beat. In fibrillation, those signals go haywire, and some of them just keep going around and around the same tissue over and over.

Defibrillation resets the heart's electrical system. Defibrillation is basically DC (direct current) that resets the polarity of the cardiac cells. (Some forms of defibrillation send one DC jolt from the top [base] of the heart to the bottom [apex], followed promptly by another DC jolt from bottom to top.) Then, when a naturally occurring stimulation from the heart's natural pacemaker occurs, the stimulation propagates properly, and the heart resumes pumping.

Defibrillation will not help with certain heart conditions, such as pulseless electrical activity (PEA).

Mr. Randi is correct, in a conventional sense, in saying that persons can be brought back from heart stoppage with a defibrillator. When the ventricles fibrillate, the heart stops pumping. Unconsciousness results within seconds, and true death will result within minutes unless the problem is addressed. And Mr. Randi is correct in saying that defibrillation shocks the heart back into a beating mode, but it does so by electrically resetting the cardiac tissues.
 
In the movie "There's Something About Mary," Pat Healy (Matt Dillon) is shown shocking a dog with a power cord from a lamp, causing the dog to regain consciousness. DO NOT EVER TRY THIS. Power cords connected to home outlets carry AC (alternating current), not DC, and defibrillation basically uses DC.

Also, as it happens, the frequency of house current (60 cycles per second in the USA, 50 cycles per second in Europe) is just "right" for INDUCING fibrillation. So using naked house current to defibrillate a patient will not help, and may actually create fibrillation where none was occurring before.
 
Any condition in which the heart stops can be considered "death," but since many persons have been "brought back" by means such as a defibrillator
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I think the problem is that this sentence shows that the patient-in-question's heart has 'stopped', and that the defibrillator has 'brought them back', thus implying that the defib 'started' up the heart (the opposite of 'stopped').

It is the next part of the sentence: "where the heart is literally shocked back into a beating mode by electrodes applied to the body" which actually and accurately discusses what the defibrillator does.

So I think the problem is the first part of the sentence could be made much clearer with the addition of the word 'beating' after 'stopped'.

Taking the whole sentence, in toto, it seems to me that the Great One is technically correct, but some readers out there might get the opposite impression because of their memories of too many movies and TV shows.
 
bignickel said:
I think the problem is that this sentence shows that the patient-in-question's heart has 'stopped', and that the defibrillator has 'brought them back', thus implying that the defib 'started' up the heart (the opposite of 'stopped').

It is the next part of the sentence: "where the heart is literally shocked back into a beating mode by electrodes applied to the body" which actually and accurately discusses what the defibrillator does.

So I think the problem is the first part of the sentence could be made much clearer with the addition of the word 'beating' after 'stopped'.

Taking the whole sentence, in toto, it seems to me that the Great One is technically correct, but some readers out there might get the opposite impression because of their memories of too many movies and TV shows.
Click to expand...
I would concur with these remarks. Usually (but not always) the signal that actually gets the heart beating again is the signal generated by the patient's own natural signal generators, the sinoatrial and atrioventricular nodes. The external defibrillator does not usually generate the signal that gets the heart going. Instead, it resets the heart so that the natural signals can propagate in a useful fashion.

You're spot on right about people getting incorrect impressions from movies and TV. In their own experience, they get a shock (such as a carpet shock) and fell their muscles contract involuntarily. On TV, they see the patient go rigid in response to external defibrillation, and assume that the shock is causing the heart to contract. Actually the defibrillation shock does not cause significant coordinated heart contraction.

The reason is that heart muscle is different from other kinds of muscle in your body (skeletal muscle and smooth muscle). If you stimulate skeletal muscle, it contracts and is ready for another contraction very quickly, almost immediately. But heart muscle has a built-in delay so that you cannot have one contraction immediately following another.
 
In a sense, bignickel, you are correct:

http://www.aps.org/WN/WN04/wn121704.cfm ]EMedicine: Treatment of Asystole[/URL]

Electrical defibrillation should not be applied indiscriminately to the patient in asystole [no pulse]. This is not only fruitless, but also detrimental, eliminating any possibility of recovering a rhythm.
Click to expand...
BillyJoe
 
Originally posted by Brown
You're spot on right about people getting incorrect impressions from movies and TV..
Click to expand...
The worst offender is the scene is just about every TV show and movie out there (where someone is dying/has been shot):

1. The steady 'ehhhhhhhhhh' sound coming from the heart monitor.
2. The heart monitor visual display showing a 'flatline'.
3. Someone yelling "(S)He's flatlining!" "Get the paddles!"
4. The patient is shocked, and lo and behold, the heart starts moving again; you can tell because the video display shows the jagged line again, and you hear the 'boop-boop' sound.
 
As a regular Nitcentral poster I was delighted to see that link posted here. My first instinct was to post it myself after reading the Commentary, but upon rereading it I realized (as mentioned above), that it is technically correct, but I don't know if it was understood that way.
 
One thing I should mention...

The AED (automatic external defibrillators) being discussed also include basic ECG functions. The only thing the user has to know is how to read and follow instructions. The AED comes with a label that shows where to place the two sticky-pad electrodes. When turned on, it monitors the electrical activity. The device will detect ventricular fibrillation (V-fib) or ventricular tachycardia (V-tach), both of which can be aide dby defibrillation. They system will not charge until it detects one of these conditions and decides fibrillation is called for. Therefore, it doesn't matter if it shouldn't be used on a stopped heart...the AED takes this into account and won't charge up to be used if it does not detect V-tach or V-fib.

There is an over-ride mode, so it can be used as a traditional defibrillator, but you have to manuall flip the switch (IIRC). Typically, the device does everything for you. It will decide when you need to shock, charge to the appropriate voltage, and even produce an audible warning before shocking. When the operator presses the shock button, the AED times the shock to the appropriate point on the ECG. THese systems have done an amazing job at making themselves fool-proof, although (as with anything) a determined fool can bypass the safeguards. Typically, however, if one follows the instructions (the machine does broadcast pre-recorded messages in English for appropriate instructions and warnings) it should work properly and appropriately.
 
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