on Tasers- by the Journal of Emergency Medical Services (JEMS)

That was a very interesting article. I worked as an EMT and then an EMT-P for a while some twenty years ago. Interesting sidebar article on the excited delirium patient; I have always suspected that a very high percentage of these patients would come back with positive tox screens.
 
The jolt that causes the muscle spasm is a mix of 50,000 volts and 0.38–1.2 amps, depending on the model. (The newer X-26 model uses less amperage than the larger M-26 version.) Although that sounds dramatic, consider that volts are quite benign; a simple static electricity charge can be as great as 20,000 volts. It's the additional amps that give the Taser charge its kick.
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Did they get those numbers right? Isn't something in that range often lethal?
 
As a negative comment they reference an article by Amnesty International. AI has long been anti-police and they have been known to make up stories to further their agenda .They are hardly a credible organization ! :mad:
 
The author references the Amnesty International article as an example of "dissent" from Taser's safety assurances, and then proceeds to debunk that dissent.
 
Silly me. I bet some idiot hooked a taser up to an ammeter (measures current). That .38-1.2A range must be the maximum possible given the batteries and wires. That's probably the peak current when the wires are shorted. The fact that it's pulsed probably kept the wires or internals from melting.
 
Some simple math here. 0.38 A @ 50 kV is 19 kW. With the pulses lasting 11 microseconds, the energy drops to 0.209 Joules. Not really very large.
.38 A would be lethal at 50 kV however. The correct number is more likely to be 0.38 mA (0.0038 amps).
The problems I see with the article are a reliance on the manufacturer for data (they would never say anything damaging), and the almost flippant comments at the end.
It would be very unlikely for a tazer to damage a pacemaker. They are designed for the higher energy pulses of a defibrillator. The more important question would be if the pacemaker lead could conduct the tazer voltage into the heart. The pacemakers are normally just under the skin near the collar bone on the left side of the chest. The wires are a direct low impedance path to the heart. Static electricity discharges to the leads of an external pacemaker are a know hazard.
Any volunteers?
Electric interactions with the body are often very odd. A 20 kV power line will often create a carbon path through the tissue that is localized but connects the entry and exit locations. This is not an easily predicted thing.
While the current limit is very likely to provide significant protection, the testing described assumes the barbs will be close together and in the thorax. What happens when the tazer catches and arm and the chest?
Any volunteers? I suggest the president of the company would be an excellent test subject.
 
It's also important to remember that electricity follows the path of least resistance. An extensive study conducted by the Heart Center at the Alfred Hospital in Victoria, Australia, concluded that the Taser's current is well below the heart's fibrillation threshold, and it's doubtful that the current travels deep enough into the body to produce any noticeable effects on the heart.3 Although difficult to measure, it's widely accepted that the electrical charge generated between the two probes travels no deeper than one-quarter inch into the body
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:cool:
 
brickeyee

Arm & chest hits are common with a Taser. The first time I used one in the field, a man was trying to commit suicide with a knife. It was a face-to-face confrontation and I tried for a quick snapshot, but he saw the laser and turned just as I fired. It was an older M-26 model and the probes embedded in his lower left arm and lower chest. The effect was immediate and profound, and dropped him like an old oak tree. He rode the full 5, but got up (without the knife) immediately after the M-26 switched off, no after effects.
 
Not sure why this subject is of interest, but.................. FWIW, we respond on all tazered persons for medical evaluation. The police here tazer a LOT of people. Very seldom are they transported to the hospital.
This is another one of those things that the media makes a big deal out of, but I would bet that hundreds of people a day are tazed worldwide, maybe thousands and very few problems occur.
 
I would not rely on the summary of medical research from an interested party without actually reviewing the data and the methodolgy used.
Claiming that the current stayed within "one-quarter inch into the body" strikes me as the result of a simulation. Given the number of assumptions that must be made to simulate body-electrical interactions this is very doughtful.
If the current stayed in this narrow zopne it would not have a signifiacnt effect on musculature since the skin and fat of a typical person or more than 1/4 inch thick.
To cause a muscular contracion the current must be delivered into the muscle to force overload of the exsiting nerve impulses. The ability to affect muscles in an area of the body does not jibe very well with current penetration of only 1/4 inch.
 
"The ability to affect muscles in an area of the body does not jibe very well with current penetration of only 1/4 inch."

You can effect the muscles with no penetration at all. For that matter you can defibrilate the heart with no penetration at all.

Not to be a jerk, but you dispute their study because you haven't actually reviewed the data and the methodolgy used. Yet your arguments are based on pure speculation on your part and we are supposed to consider that valid ?
 
444 said:
You can effect the muscles with no penetration at all. For that matter you can defibrilate the heart with no penetration at all.
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Are you claiming that electrically induced defibrilation can be accomplished without electric charge reaching the heart muscle? That other muscles can be affected by electric charge without ever receiving same?

Interesting.....what then is the physiology?
Rich
 
"You can effect the muscles with no penetration at all. For that matter you can defibrilate the heart with no penetration at all."

The only way an electric current can have any affect on the body is by flowing through the affected tissue. Period. No current flow, no effect.

A defibrillator uses a higher voltage for external use to ensure adequate current density through the heart to force complete depolarization. If you fail to use enough conductive gel, or do not hold the paddles tight to the skin you can even produce burns.
Open defibrillation (during surgery) uses far lower voltages (~2-10V) since the paddles are placed directly against the heart. Since there is effectively no current spreading the low voltages work very well. Absent a skin barrier humans are pretty good conductors.

I do not need to review a study to already notice significant defects in the analysis posted. If the current is confined to the outer 1/4 inch of skin it cannot have the effects the Taser vendor is claiming.
This indicates that either the interpretation is wrong or the study is wrong. Take your pick.
 
I think I see the conflict:

Brickeyee-
I think you misinterpret what the study says:
it's doubtful that the current travels deep enough into the body to produce any noticeable effects on the heart. Although difficult to measure, it's widely accepted that the electrical charge generated between the two probes travels no deeper than one-quarter inch into the body (see photo below).
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They're saying that the charge between the two probes travels no more than 1/4 inch deep. But I doubt any medical person would try to argue that the full charge packet travels between those two points, when the very mechanism for incapacitation requires otherwise. The statement, to my read, is in relation to claims that heart attack can follow based on reading the raw voltage numbers on the device.

444's argument that no electrical stimulation need be required to affect a muscle remains, however, curious.
Rich
 
No, I find the idea that a charge with a depth of 1/4 inch could produce any of the physiological affects they are claiming to be at best amusing.
Whoever even wrote the line does not have a clue about how electricity travels in a conductor - human or otherwise. A comment like that should lead one to question everything else a study reports since the statement is pretty demonstrably false.
It demonstrates a dangerous lack of knowledge that calls into question any other conclusions made.
While the current limit of the device does make it very unlikely it can produce sufficient current density in the heart to have any significant affect. The last numbers I remember are ~10 mA/cm^2 in the cardiac tissue itself. The Tazer website mentions currents of 3.6 mA with an average of 2.1 mA (average is not normally used to describe electric current) the device could not produce a known lethal current density, but this still does not indicate a ‘no affect’ level (just as a reference point, a GFCI is set to trip at ~5 mA of current imbalance).
It also indicates an author/editor very unfamiliar with electricity to allow an error of 1000 times to creep in and not be caught.
 
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