Technical ReportPDF Available

Conducted Electrical Weapon Drive-Stun Mode: Skin Rub vs. Injection

Authors:

Abstract and Figures

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 primarily through the dermis and fat layer between the elec- trodes and there is no significant penetration beyond the subdermal (or subcutaneous) fat layer. 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 significantly different effects.
Content may be subject to copyright.
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.
References:
[1] G. M. Vilke and T. C. Chan, "Less lethal technology:
medical issues," Policing, vol. 30, pp. 341-357, 2007.
[2] M. White and J. Ready, "The TASER as a Less Lethal
Force Alternative. Findings on Use and Effectiveness in
a Large Metropolitan Police Agency," Police Quarterly,
March 2006 2006.
[3] D. J. Valentino, R. J. Walter, A. J. Dennis, B. Margeta,
F. Starr, K. K. Nagy, et al., "Taser X26 discharges in
swine: ventricular rhythm capture is dependent on
discharge vector," J Trauma, vol. 65, pp. 1478-85;
discussion 1485-7, Dec 2008.
[4] J. Wu, H. Sun, A. O'Rourke, S. Huebner, P. Rahko, J.
Will, et al., "Taser blunt dart-to-heart distance causing
ventricular fbrillation in pigs," IEEE Transactions on
Biomedical Engineering, p. in press, 2008.
[5] D. J. Glomset and A. T. Glomset, "A morphologic study
of the cardiac conduction system in ungulates, dog, and
man: Part II: The purkinje system," American Heart
Journal, vol. 20, pp. 677-701, 1940.
[6] D. Sedmera and R. G. Gourdie, "Why do we have
Purkinje fibers deep in our heart?," Physiol Res, vol. 63
Suppl 1, pp. S9-S18, Feb 24 2014.
[7] R. P. Holland and H. Brooks, "The QRS complex during
myocardial ischemia. An experimental analysis in the
porcine heart," J Clin Invest, vol. 57, pp. 541-50, Mar
1976.
[8] G. P. Walcott, M. W. Kroll, and R. E. Ideker,
"Ventricular fibrillation: are swine a sensitive species?,"
J Interv Card Electrophysiol, vol. 42, pp. 83-9, Mar
2015.
[9] M. A. Brave, D. Lakkireddy, M. Kroll, and D. Panescu,
"Studies Using Small Swine May Exaggerate Electrical
Safety Risks," Conf Proc IEEE Eng Med Biol Soc, vol.
36, p. in press, 2014.
[10] M. Kroll, D. Panescu, J. Brewer, D. Lakkireddy, and M.
Graham, "Weight Adjusted Meta-Analysis of
Fibrillation Risk From TASER Conducted Electrical
Weapons," Proceedings of the American Academy of
Forensic Science, pp. 177-177, Feb 2009.
[11] G. M. Vilke, C. Sloane, S. Levine, T. Neuman, E.
Castillo, and T. C. Chan, "Twelve-lead
electrocardiogram monitoring of subjects before and
after voluntary exposure to the Taser X26," Am J Emerg
Med, vol. 26, pp. 1-4, Jan 2008.
[12] D. Panescu, M. Kroll, and R. Stratbucker, "Finite
Element Modeling of Fibrillation Risk from TASER
Conducted Electrical Weapons," IEEE Trans Biomed
Eng, in press 2008.
[13] J. D. Ho, D. M. Dawes, R. F. Reardon, A. L. Lapine, B.
J. Dolan, E. J. Lundin, et al., "Echocardiographic
Evaluation of a TASER-X26 Application in the Ideal
Human Cardiac Axis," Acad Emerg Med, 2008.
[14] G. M. Vilke, C. M. Sloane, K. D. Bouton, F. W.
Kolkhorst, S. D. Levine, T. S. Neuman, et al.,
"Physiological effects of a conducted electrical weapon
on human subjects," Ann Emerg Med, vol. 50, pp. 569-
75, Nov 2007.
[15] G. Vilke, C. Sloane, S. Levine, T. Neuman, E. Castillo,
and T. Chan, "Does the Taser Cause Electrical Changes
in Twelve Lead ECG Monitoring of Human Subjects," J
Acad Emerg Med, vol. Abstracts, p. 257, 2007.
[16] G. Vilke, C. Sloane, K. Bouton, S. Levine, T. Neuman,
E. Castillo, et al., "Cardiovascular and Metabolic Effects
of the TASER on Human Subjects," J Acad Emerg Med,
vol. 14, p. 104, May 2007.
[17] R. E. Ideker and D. J. Dosdall, "Can the direct cardiac
effects of the electric pulses generated by the TASER
X26 cause immediate or delayed sudden cardiac arrest
in normal adults?," Am J Forensic Med Pathol, vol. 28,
pp. 195-201, Sep 2007.
[18] S. J. Holden, R. D. Sheridan, T. J. Coffey, R. A.
Scaramuzza, and P. Diamantopoulos, "Electromagnetic
modelling of current flow in the heart from TASER
devices and the risk of cardiac dysrhythmias," Phys Med
Biol, vol. 52, pp. 7193-209, Dec 21 2007.
[19] D. M. Dawes, J. D. Ho, R. F. Reardon, and J. R. Miner,
"Echocardiographic evaluation of TASER X26 probe
deployment into the chests of human volunteers," Am J
Emerg Med, vol. 28, pp. 49-55, Jan 2010.
[20] D. P. Zipes, "Sudden cardiac arrest and death following
application of shocks from a TASER electronic control
device," Circulation, vol. 125, pp. 2417-22, May 22
2012.
[21] G. M. Vilke, T. C. Chan, and S. Karch, "Letter by Vilke
et al regarding article, "sudden cardiac arrest and death
following application of shocks from a TASER
electronic control device"," Circulation, vol. 127, p.
e258, Jan 1 2013.
[22] J. D. Ho and D. M. Dawes, "Letter by Ho and Dawes
regarding article, "sudden cardiac arrest and death
following application of shocks from a TASER
electronic control device"," Circulation, vol. 127, p.
e259, Jan 1 2013.
[23] W. G. Heegaard, H. R. Halperin, and R. Luceri, "Letter
by Heegaard et al regarding article, "Sudden cardiac
arrest and death following application of shocks from a
TASER electronic control device"," Circulation, vol.
127, p. e260, Jan 1 2013.
[24] S. Goudge, "The health effects of conducted energy
weapons: The Expert Panel on the Medical and
Physiological Impacts of Conducted Energy Weapons.,"
Council of Canadian Academies, p.
http://www.scienceadvice.ca/uploads/eng/assessments
and publications and news
releases/cew/cew_fullreporten.pdf, 15 October 2013.
[25] M. W. Kroll, D. R. Lakkireddy, J. R. Stone, and R. M.
Luceri, "TASER electronic control devices and cardiac
arrests: coincidental or causal? Supplement,"
Circulation, vol. 129, p. On Line Supplement, Jan 7
2014.
[26] American Medical Association, "Use of Tasers by Law
Enforcement Agencies (Resolution 401, A-08),"
Resolutions of the 2009 AMA National Convention,
2009.
[27] J. Morgan. (2011). Study of Deaths Following Electro
Muscular Disruption. Available:
http://www.ncjrs.gov/pdffiles1/nij/222981.pdf
[28] W. P. Bozeman, E. Teacher, and J. E. Winslow,
"Transcardiac Conducted Electrical Weapon (TASER)
Probe Deployments: Incidence and Outcomes," J Emerg
Med, Jun 4 2012.
[29] M. Jolley, J. Stinstra, J. Tate, S. Pieper, R. Macleod, L.
Chu, et al., "Finite element modeling of subcutaneous
implantable defibrillator electrodes in an adult torso,"
Heart Rhythm, vol. 7, pp. 692-8, May 2010.
[30] D. Panescu, M. W. Kroll, and R. A. Stratbucker,
"Medical safety of TASER conducted energy weapon in
a hybrid 3-point deployment mode," Conf Proc IEEE
Eng Med Biol Soc, vol. 31, pp. 3191-4, 2009.
[31] E. K. Rhee, "Finite element modeling of novel ICD
configurations in pediatric and congenital heart disease:
validation of the MacGyver principle?," Heart Rhythm,
vol. 5, pp. 573-4, Apr 2008.
[32] D. Panescu, M. W. Kroll, and R. A. Stratbucker,
"Theoretical possibility of ventricular fibrillation during
use of TASER neuromuscular incapacitation devices,"
Conf Proc IEEE Eng Med Biol Soc, vol. 2008, pp. 5671-
4, 2008.
[33] H. Sun and J. G. Webster, "Estimating neuromuscular
stimulation within the human torso with Taser stimulus,"
Phys Med Biol, vol. 52, pp. 6401-11, Nov 7 2007.
[34] R. A. Stratbucker, M. W. Kroll, W. McDaniel, and D.
Panescu, "Cardiac current density distribution by
electrical pulses from TASER devices," Conf Proc IEEE
Eng Med Biol Soc, vol. 28, pp. 6305-7, 2006.
[35] D. Panescu, M. W. Kroll, I. R. Efimov, and J. D.
Sweeney, "Finite element modeling of electric field
effects of TASER devices on nerve and muscle," Conf
Proc IEEE Eng Med Biol Soc, vol. 28, pp. 1277-9, 2006.
[36] L. C. Hunt and A. L. de Jongh Curry, "Transthoracic
atrial defibrillation energy thresholds are correlated to
uniformity of current density distributions," Conf Proc
IEEE Eng Med Biol Soc, vol. 26, pp. 4374-7, 2006.
[37] Y. L. Zhang and C. Bajaj, "Finite Element Meshing for
Cardiac Analysis," Univ. of Texas at Austin: ICES
Technical Report, 2004 2004.
[38] M. A. Camacho, J. L. Lehr, and S. R. Eisenberg, "A
three-dimensional finite element model of human
transthoracic defibrillation: paddle placement and size,"
IEEE Trans Biomed Eng, vol. 42, pp. 572-8, Jun 1995.
[39] D. Panescu, J. G. Webster, and R. A. Stratbucker,
"Modeling current density distributions during
transcutaneous cardiac pacing," IEEE Trans Biomed
Eng, vol. 41, pp. 549-55, Jun 1994.
[40] S. Singh and S. Saha, "Electrical properties of bone. A
review," Clin Orthop Relat Res, pp. 249-71, Jun 1984.
[41] D. Panescu, M. Kroll, C. Iverson, and M. A. Brave,
"The Sternum as an Electrical Shield," Conf Proc IEEE
Eng Med Biol Soc, vol. 36, pp. 4464-4470, 2014.
[42] A. J. Dennis, D. J. Valentino, R. J. Walter, K. K. Nagy,
J. Winners, F. Bokhari, et al., "Acute effects of TASER
X26 discharges in a swine model," J Trauma, vol. 63,
pp. 581-90, Sep 2007.
[43] R. J. Walter, A. J. Dennis, D. J. Valentino, B. Margeta,
K. K. Nagy, F. Bokhari, et al., "TASER X26 discharges
in swine produce potentially fatal ventricular
arrhythmias," Acad Emerg Med, vol. 15, pp. 66-73, Jan
2008.
[44] D. Lakkireddy, D. Wallick, A. Verma, K. Ryschon, W.
Kowalewski, O. Wazni, et al., "Cardiac effects of
electrical stun guns: does position of barbs contact make
a difference?," Pacing Clin Electrophysiol, vol. 31, pp.
398-408, Apr 2008.
[45] D. J. Valentino, R. J. Walter, A. J. Dennis, K. Nagy, M.
M. Loor, J. Winners, et al., "Acute effects of MK63 stun
device discharges in miniature swine," Mil Med, vol.
173, pp. 167-73, Feb 2008.
[46] D. J. Valentino, R. J. Walter, K. Nagy, A. J. Dennis, J.
Winners, F. Bokhari, et al., "Repeated thoracic
discharges from a stun device," J Trauma, vol. 62, pp.
1134-42, May 2007.
[47] D. J. Valentino, R. J. Walter, A. J. Dennis, K. Nagy, M.
M. Loor, J. Winners, et al., "Neuromuscular effects of
stun device discharges," J Surg Res, vol. 143, pp. 78-87,
Nov 2007.
[48] J. Ho, A. Lapine, S. Joing, R. Reardon, and D. Dawes,
"Confirmation of respiration during trapezial conducted
electrical weapon application," Acad Emerg Med, vol.
15, p. 398, Apr 2008.
[49] G. M. Vilke, W. P. Bozeman, and T. C. Chan,
"Emergency Department Evaluation after Conducted
Energy Weapon Use: Review of the Literature for the
Clinician," J Emerg Med, Jan 8 2011.
... Studies show that when a pulse is detected, this has a 95% accuracy. [ 16 15-60 s Cessation of normal breathing 15-60 s. [25,26] ...
Presentation
Full-text available
Brave, M. (2022). TASER® Energy Weapon Electrocution Published Checklists Reference Bundle Table. February 11, 2022.
... These probes are designed to penetrate and stick in clothing or skin tissue. TASER activation in probe mode is designed to produce neuromuscular incapacitation (NMI), which can generally involve a fall to the ground or interrupted motor control (Adams & Jennison, 2007;Kroll, 2015;Paoline et al., 2012;Ready et al., 2008). If effective, citizens are typically physically incapacitated, while retaining cognition and memory of the event (White & Ready, 2007). ...
Article
Full-text available
Since their emergence within the field of policing, the use of conducted energy devices (CEDs) has produced a great deal of debate. However, few empirically rigorous studies have shed light on the extent to which CEDs (e.g., TASERs) are actually successful at gaining citizen compliance. As such, we examine 918 TASER cases collected from three police agencies to assess effectiveness in relation to citizen compliance. Findings demonstrate that officers generally classify the TASER as effective, but the level of effectiveness varies depending on whether it was used in probe or drive-stun mode. Multivariate regression models also identify a number of significant variables related to TASER effectiveness, including citizen (e.g., height, weight, gender, impairment) and officer (e.g., gender) characteristics. We discuss the findings in relation to those found in prior studies, as well as implications for research, policy, and practice.
... Most of the ITPs occur with drive-stuns which are well established as having no deleterious effects outside of short-term minor contact burns. [20][21][22] Moreover, the inadvertent drive-stun trigger pull is almost always with the weapon far away from the subject as the officer's opposite hand is the one in contact with the subject. For the minority of cases that began as a probe-mode deployment, the connection has usually been broken by the ground struggle. ...
Technical Report
Full-text available
... The drive-stun mode (without probes) is used with some subjects and probes occasionally miss the subject or become lodged in thick clothing. Hence, the average number of probe landings is only 1.42 per subject (5,6). This means that there have been about 3.3 million CEW probes that have at least partially penetrated the body in field subjects. ...
Article
Concern has been raised over the infection risk of the TASER electrical weapon since the probes penetrate the skin. The manufacturing process produces unsterilized probes with a 5% rate of Staphylococcus aureus contamination. Voluntary recipients (n = 208) of probe exposures were surveyed and there were no self-observations of infection. With over 3.3 million probe landings, there have been 10 case reports of penetrations of sensitive tissue with no reported infections. The electrical field was modeled and found that the electrical pulses generate a field of over 1200 V/mm on the dart portion. This is sufficient to sterilize the dart via electroporation. Electrical weapon probes appear to have a very low (possibly zero) rate of infection. The factors leading to this low infection rate appear to be a manufacturing process producing a low rate of bacterial contamination and the pulses sterilizing the dart via electroporation.
Article
Full-text available
Introduction: The TASER(®) conducted electrical weapon (CEW) delivers electrical pulses that can temporarily incapacitate subjects. We analyzed the distribution of TASER CEW currents in tissues posterior to the sternum to understand the likelihood of triggering cardiac arrhythmias. We also assessed the electrical `shielding' effects of the sternum. Methods and results: Finite element modeling (FEM) was used to approximate the current density and electric field strength in tissues around the sternum. We analyzed 2 CEW dart deployment scenarios: (a) both darts over the anterior aspect of the sternum; and (b) a CEW dart anterior to the sternum and the other over the abdomen. In both scenarios, the sternum provided significant attenuation of CEW currents. Particularly, both FEMs predicted that the residual electrical current or charge from CEWs would be insufficient to cause either cardiac capture or induction of ventricular fibrillation at locations where cardiac tissue would reside relative to the posterior aspect of the sternum. Conclusion: The sternum offers significant 'shielding' effect and protects the tissues posterior to it against effects of electrical current flow from anteriorly-placed CEW electrodes.
Article
Full-text available
Purkinje fibers were the first discovered component of the cardiac conduction system. Originally described in sheep in 1839 as pale subendocardial cells, they were found to be present, although with different morphology, in all mammalian and avian hearts. Here we review differences in their appearance and extent in different species, summarize the current state of knowledge of their function, and provide an update on markers for these cells. Special emphasis is given to popular model species and human anatomy.
Article
Full-text available
Despite its adoption by more than 8,000 law enforcement agencies in the United States and abroad, there is little empirical research examining use of the TASER by police officers. This article investigates the use and effectiveness of the weapon by examining all TASER deployments by police officers in a large metropolitan department during a 3-year period (2002 to 2004; n = 243). Findings indicate that the TASER was used almost exclusively against violent suspects classified as “emotionally disturbed” by emergency service officers with supervisors present. Despite use on a population perceived as being higher risk for injury, findings indicate that the TASER was effective, as 85% of suspects were incapacitated and taken into custody without further incident. The article concludes with a discussion of implications for continued use of the TASER and the need for additional research before any definitive conclusions about use and effectiveness of the weapon can be drawn.
Article
Legislation and sentiment have pushed large-animal electrophysiological research from the canine to the swine model. Anecdotal experience suggests that the swine is particularly sensitive to ventricular fibrillation (VF) induction, and radiofrequency ablation studies are consistent with this. Currently, no data exist directly comparing the VF threshold (VFT) in humans to swine. Because of the perceived difference in vulnerability to VF induction, we hypothesized that the VFT would be lower in swine compared to humans. Six anesthetized open-chested swine, 31 ± 2 kg, were studied that were part of an ongoing study with up to 6 h of previous closed-chest percutaneous pacing with repeated VF cycles. Similar to the human study of Horowitz et al., 24 pulses of 4 ms each were applied at a rate of 100 Hz during the ST segment to the epicardium via a pair of 7-mm diameter platinum electrodes whose centers were 15 mm apart. Current was increased until VF was induced. The swine right ventricle (RV) VFT was 9.7 ± 2.1 mA [median = 9.0, interquartile range (IQR) = 7.8-12.0], and the left ventricle (LV) VFT was 10.7 ± 2.2 mA [median = 10.5, IQR = 8.8-12.5] (p = NS). Horowitz reported the RV VFT in six patients as 24.3 ± 5.2 mA [median = 24.5, IQR = 19.0-29.3] and the LV VFT in ten patients as 33.6 ± 9.5 mA [median = 36.5, IQR = 27.3-42.3] (p = .11). Both the RV and LV VFTs were lower for swine (p < 0.003), and each of the mean and median VFTs for the ventricles together was one third that of the humans. Swine are about three times as sensitive to the electrical induction of VF as are humans.
Article
After attending this presentation, attendees will understand the risk of CEW fibrillation for human beings of various body weights. This presentation will impact the forensic community by demonstrating how a forensic investigator will be able to estimate the risk of CEW induced fibrillation with an arrest related death.
Article
Purpose – Less lethal weapons have become a critical tool for law enforcement when confronting dangerous, combative individuals in the field. The purpose of this paper is to review the medical aspects and implications of three different types of less lethal weapons. Design/methodology/approach – The paper conducted a comprehensive medical literature review on blunt projectiles, irritant sprays including oleoresin capsicum (OC), and conducted energy devices such as the Taser™. It reviews the history, mechanisms of action, intended and other physiologic effects, and medical safety risks and precautions of these devices. In particular, the paper focuses on the issue of sudden in‐custody death and less lethal weapons, reviewing case reports, animal research and human investigative studies on this topic. Findings – In general, these three different types of less lethal weapons have been effective for their intended use. Each type of less lethal weapon has a number of physiologic effects and specific medical issues that must be considered when the weapon is used. There is no clear evidence that these devices are inherently lethal, nor is there good evidence to suggest a causal link between sudden in‐custody death and the use of irritant sprays or conducted energy devices. Originality/value – While further research on the physiologic effects of these devices is needed, this paper provides law enforcement with a medical review of less lethal weapons including blunt projectiles, irritant sprays such as OC, and conducted energy devices such as the Taser.