Page 74 - Journal of Special Operations Medicine - Spring 2015

of law enforcement, 10 (16%) deaths occurred in a cor­ small (less than 4 inches) or when used in “drive stun”
rectional facility, and 11 (18%) deaths occurred in a mode, the device is intended to induce compliance by
mental health facility. Physical restraints were used in 36 producing pain without neuromuscular incapacitation.
(58%). When physical restraint was required, 29 (81%) The perceptions of pain, discomfort, and sensory over­
occurred while in the custody of law enforcement. Toxi­ load occur from the activation of type III A­δ myelinated
cology was positive in 37 (60%), negative in 17 (27%), sensory fibers. 15
and not performed in 8 (13%).
Despite the relative safety of CEWs observed during
Of those manifesting the signs of ExDS who died in more than 2 million probe deployments during opera­
custody, death occurred typically within 1 hour of first tions and in training, there remains concern that these
contact with the police. More than 75% of these per­ weapons may contribute to the sudden death associated
sons died at the scene or during initial transport. An with ExDS. In a study of 1,201 cases of suspects sub­
16
8
important sign of impending cardiopulmonary arrest jected to the use of TASER, 99.75% had no significant
while in custody was the sudden and unpredicted ces­ injuries. A Canadian study in 2008 identified 326
17
sation of struggling against restraints. This cessation of deaths in North America associated with TASER use
9
struggling has been termed the “period of peril.” Dur­ from media reports and independent research, 20 of
10
ing this time, all resistance and exertion stop and the which occurred in Canada. The authors noted that this
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subject appears calm. In the 2 to 5 minutes immediately statistic did not, by itself, establish a causal relationship
following intense activity, there is a surge in catechol­ between the use of a TASER and sudden death. More
amine levels that may reach 10 times baseline levels. recently, a panel of medical experts was convened in
High catecholamine levels can cause serum potassium Canada to conduct an independent evaluation of exist­
levels to fall as potassium moves into cells. This fall in ing research aimed at examining the medical and physi­
serum potassium may predispose these patients to car­ ological impacts of CEWs. They noted in their report:
19
diac arrhythmias and sudden death. 11
• “Some animal studies suggest CEWs can induce fatal
cardiac arrhythmias (abnormal heart rhythm) when a
Safety of CEWs in Association With ExDS
number of discharge characteristics, either alone or in
Law enforcement officers increasingly use CEWs as an combination, are in place: probe placement on oppo­
effective intermediate use of force tool intended to in­ site sides of the heart (i.e., current is delivered across
duce compliance with police commands and to affect an the heart), probes embedded deeply near the heart,
arrest. The effectiveness of these weapons is evidenced increased charge, prolonged discharges, or repeated
by a 10­year experience showing a reduced incidence of discharges. These studies indicate the biological plau­
injuries to suspects and police officers and a reduction sibility of adverse health outcomes following CEW
in claims for excessive force compared with other uses exposure.
of force techniques such as empty hand techniques and • A small number of human cases have found a tem­
use of a baton. 12 poral relationship between CEWs and fatal cardiac
arrhythmias, but available evidence does not allow
A CEW in widespread police use is the TASER X26 for confirmation or exclusion of a causal link. If a
®
(Taser International; www.taser.com). When deployed, causal link does exist, the likelihood of a fatal cardiac
it uses compressed nitrogen to fire two small probes arrhythmia occurring would be low, but further evi­
tethered by thin wires to distances of 25 feet, up to dis­ dence is required to confirm the presence and magni­
tances of 35 feet. The weighted probes possess barbs tude of any risk.
9mm in length designed to penetrate the skin or become • The roles of co­factors common to real­world CEW
lodged on clothing. Each cartridge has a serial number incidents (e.g., intoxication, exertion, restraint) and
and, when deployed, leaves multiple identifiable tags at other co­factors (e.g., body type, existing health com­
the scene. When fired, the weapon delivers a 5­second plications) that may increase susceptibility to adverse
burst of approximately 400 volts (1,200 V peak), de­ effects have not been adequately tested to properly
livered at a current of approximately 2.1 mA, and at establish an understanding of increased vulnerability
19 pulses per second. The device can also deliver an in humans.”
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open circuit voltage of up to 50,000 volts to conduct
across air or clothing. When the contact distance be­ While some studies have produced results implicating
tween probes exceeds 4 inches, neuromuscular incapaci­ that CEWs could potentially contribute to in­custody
tation occurs through the activation of type A­α motor death, large­scale prospective studies involving hu­
neurons that control skeletal muscle contraction. Maxi­ man subjects exposed to CEWs for up to 15 seconds
mum incapacitation occurs when probe spread exceeds have failed to demonstrate any clear causal relation­
9 to 12 inches. When the distance between probes is ship between TASER use and laboratory abnormalities,
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64 Journal of Special Operations Medicine Volume 15, Edition 1/Spring 2015