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Conducted Electrical Weapon Drive-Stun Mode
Skin Rub vs. Injection
Mark W. Kroll, PhD, FHRS, FACC, FAIMBE*
1 March 2015
In probe mode, the TASER handheld CEW (Conduct-
ed Electrical Weapon) uses compressed nitrogen to
fire 2 small probes at typical distances of up to 7.7 m
(meters) or 25 feet.[1, 2] (Other TASER cartridge
models can reach a distance of 11 m or 35 feet.)
When the CEW trigger is pulled, the high voltage first
serves to open the nitrogen cartridges to release the
nitrogen to propel the probes as directed. These probes
themselves are designed to pierce or become lodged in
most light clothing (which is usually overcome by the
50,000 V-arcing capability). The sharp portion of the
probe is typically 9-13 mm (millimeters) long and will
typically penetrate the epidermis and dermis to a
depth of ~6 mm for a good electrical connection.
Even as a strong static electrical shock will
temporarily incapacitate someone, a series of 19 very
short duration shocks per second can cause temporary
muscle incapacitation. The ultra-short duration elec-
trical pulses applied by TASER CEWs are intended to
stimulate Type A-α motor neurons, which are the
nerves that control skeletal muscle contraction, but
without a high-risk of stimulating cardiac muscle.
This typically leads to a loss of regional muscle con-
trol and a fall to the ground to end a violent confronta-
tion or suicide attempt. 1
Small swine of 30 kilograms (65 pounds) can
occasionally, but rarely, be put into VF when the
CEW probes are put within a few millimeters of the
heart.[3] One study used a custom long plunging
probe to deliver the CEW current almost directly
(within 6 mm or ¼ inch) to the heart of a pig in order
to induce VF.[4] Pigs are extremely sensitive to elec-
trical currents due to their hearts being literally wired
“outside-in” compared to a human’s (being wired “in-
side-out”). [5-7] The swine heart needs 2/3 less cur-
rent to go to VF (ventricular fibrillation) compared to
the human heart from external stimulation.[8] I.e. the
swine is 3 times as sensitive to electrocution as is the
human. There are numerous problems with the swine
model that significantly exaggerate the electrocution
risk.[9] This CEW-electrocution effect is also con-
fined to small swine.[10] In stark contrast, human
1 *Dr. Kroll is a frequent expert in law-enforcement litigation and is an
advisor and director for TASER Intl.
studies consistently show no demonstrated risk of VF
with a CEW application.[11-19]
The VF risk question has been clouded by the
activities of the expert witnessing, and associated me-
dia statements and publications, of a retired controver-
sial cardiologist, Douglas Zipes, MD. In May 2012,
Dr. Zipes published 8 of his expert witness cases —
where he had opined electrocution by the CEW.[20]
These cases were provided to him by plaintiffs’ attor-
ney John Burton and a legal associate. The case series
was rife with errors including the comment that the
subjects were “clinically normal.” (This error was cor-
rected in an addendum after being brought up in a
deposition.) Numerous other errors have been pointed
out including the listing of a case where the CEW
probes missed the subject and thus could hardly be
blamed for contributing to his death.[21-23] Subse-
quently, the journal added the clarification that Attor-
ney Burton be acknowledged as a contributor to the
paper.
The Canadian Council of Science convened
an expert panel and reviewed the scientific literature
on CEWs and specifically commented on this
Zipes/Burton case series and dismissed it thusly:[24]
The study by Zipes is particularly questionable
since the author had a potential conflict of interest
and used eight isolated and controversial cases as
part of the analysis.
Around the same time, Circulation, the publisher of
the Zipes’ anecdotes paper solicited a refutation paper
published in January 2014.[25] It methodically con-
sidered the available evidence and showed that none
of the Zipes’ expert witnessing anecdotes represented
electrocution by the CEW.
This appears to be the consensus of the scien-
tific and medical community as shown by various po-
sition papers. For example: the June 2009 American
Medical Association White (Position) Paper conclud-
ed:[26]
Furthermore, no evidence of dysrhythmia or myo-
cardial ischemia is apparent, even when the barbs
are positioned on the thorax and cardiac apex.
On May 24, 2011, the National Institute of Justice,
after a 5-year study, concluded:[27]
Current research does not support a substantially
increased risk of cardiac arrhythmia in field situa-
tions, even if the CED darts strike the front of the
chest. There is currently no medical evidence that
CEDs pose a significant risk for induced cardiac
dysrhythmia in humans when deployed reasonably.
Finally, in June 2012, Bozeman stated:[28]
The risk of such dysrhythmias, even in the pres-
ence of a transcardiac CEW discharge, is low, and
suggest that policies restricting anterior thoracic
discharges of CEWs based on cardiac safety con-
cerns are unnecessary.
Current Flow in the Body
The flow of electrical current in the body is well un-
derstood and has been the subject of 100's of scientific
papers.[29-39] The simplest analogy is the 1st to 2nd
baseline in baseball. See Figure 1. The runners can go
directly between the bases but they typically curve out
a bit. Similarly, with 2 electrodes in the skin, the cur-
rent flow “dives” in somewhat just like a runner’s path
in baseball. The further the electrodes are apart, the
deeper the “dive” of the current. This analysis is accu-
rate for a homogenous conductor like saltwater or fat.
However, the body’s skeletal muscle layer preferable
directs current around the outside of the body since
electrical current vastly prefers to follow the grain of
the muscle instead of going transverse and penetrating
into the body.
A runner might deviate somewhat from a
straight line but would never run out into the outfield
or wander into the bleachers. Similarly, with 2 CEW
electrodes on the chest, no current passes into the legs
or brain. That would be like a runner going into the
outfield and then climbing up into the seats and then
back to 2nd base.
Figure 1. Graphic of electrical current flow in the body analogized to baseball.
An important exception occurs around bone. Mature
calcified bone is an insulator and can thus not conduct
electrical current.[40] A CEW probe landing in the
sternum will pass very little current. What current is
passed will be defused around the surface of the chest
and will last tend to not affect the heart even though
parts of the heart are directly beneath the sternum.[41]
Current Flow With Drive-Stun
Alternatively, the CEW may be used in a “drive-stun”
mode by pushing the front of the weapon into the skin
to function as a “stun gun.” With the fixed electrodes
only 4 cm (centimeters) or 1.6 inches apart — and the
lack of skin penetration — the current flow is primari-
ly through the dermis and fat layer between the elec-
trodes and there is no significant penetration beyond
the subdermal (or subcutaneous) fat layer. See Figure
2. Since there is insufficient depth of current flow to
capture muscles, the drive-stun mode serves only as a
compliance technique.
To make an analogy to medicine, drive-stun is
like rubbing an ointment on the skin compared to the
probe mode, which is like an injection. They have sig-
nificantly different effects.
As mentioned above, small swine (30 kg or 65
pounds) can occasionally be put into VF when fully-
embedded CEW probes are nearly touching the
heart.[42, 43] However, it is not possible to fibrillate
even small swine with a transcutaneous CEW drive-
stun application.[44-47] The electrical current simply
does not penetrate deeply enough to affect any human
muscles or organs. In fact, with a CEW drive-stun
application directly over the human phrenic nerves
(the nerves that control breathing) there is no
effect.[48]
The American Academy of Emergency Medi-
cine (AAEM) has the following guideline on drive-
stun applications:[49]
For patients who have undergone drive stun or
touch stun ECD exposure, medical screening
should focus on local skin effects at the exposure
site, which may include local skin irritation or mi-
nor contact Allen. This recommendation is based
on a literature review in which thousands of volun-
teers and individuals in police custody have had
drive stun ECDs used with no untoward effects be-
yond local skin effects.
Figure 2. The majority of the drive-stun current is confined to the fat and dermis layer.
The National Institute of Justice, 5-year review of
CEWs, found:[27]
Risk of ventricular dysrhythmias is exceedingly
low in the drive-stun mode of CEDs because the
density of the current in the tissue is much lower in
this mode.
The Federal Court of Appeals for the 9th Circuit
[Brooks v Seattle], and others, have concluded:
The [TASER CEW]’s use in “touch” or “drive-
stun” ... involves touching the [TASER CEW] to
the body and causes temporary, localized pain on-
ly. ... this usage was considered a Level 1 tactic,
akin to “pain compliance applied through the use
of distraction, counter-joint holds, hair control
holds, [and pepper spray]” and used to control pas-
sively or actively resisting suspects.
CEW drive-stun applications have no clinically signif-
icant physiological or pathological effects.
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