Trauma/original researchPhysiological Effects of a Conducted Electrical Weapon on Human Subjects
Introduction
There has been growing public demand for effective, less lethal law enforcement weapons, which include blunt impact weapons such beanbag guns or rubber bullets, mace, pepper spray, and batons. The Taser, a conducted electrical weapon, is an electrical law enforcement and self-defense device originally developed in the 1970s and manufactured by Taser International (Scottsdale, AZ). Early versions were bulky and often ineffective. Various models of the Taser device have been developed, and their newest version, the X26, differs from the previous model, the M26, mainly in the size and shape of the device.
The National Institute of Justice reports that 9,800 US law enforcement agencies authorize the Taser device, which is being carried by more than 225,000 officers.1 Additionally, they report that more than 120,000 US citizens also have a Taser device. Although the actual number of uses is unknown, they have reported that the Taser has been used on more than 150,000 volunteers during training and in more than 100,000 “real-life” police confrontations. The manufacturer asserts that the device helps officers avoid the use of deadly force while lowering the risk of injury to officers.
The Taser X26 is designed to be deployed up to 7 m from the subject. The operator fires the device, releasing 2 9-mm barbs attached to the gun by thin, 7-m copper wires. When the circuit is completed, an electrical pulse of 5 seconds’ duration is automatically delivered through the wires to incapacitate the subject by causing involuntary tetanic muscular contractions. The officer may deliver continued electricity by pulling the device trigger again.
Although the effect of the Taser is poorly studied, it is generally regarded as safe2, 3, 4 and has been approved by the US Consumer Product Safety Commission for the current indication for which it is being used. Most of the data supporting the product’s approval by the US Consumer Product and Safety Commission was based on theoretic calculations and not animal or human studies.5
There have been a number of reports of sudden death after Taser administration. Amnesty International6 reports “152-Taser related deaths” since 2001, and the Arizona Republic7 reports “167 cases of death following stun gun use” since 1999. The majority of deaths in humans who were exposed to a Taser device were associated with illicit drug use, especially phencyclidine, methamphetamine, and cocaine.4, 8, 9 However, there have been several deaths reported in individuals after Taser exposure who were not under the influence of illicit drugs. These cases generally involved a clinical presentation of “excited delirium” and other comorbid factors that were likely to be related as the cause of the suspect’s death.10, 11, 12 Most case reports and police reports note that such suspects who are shocked with a Taser go into cardiac arrest 5 to 40 minutes later.13 If a lethal dysrhythmia, particularly ventricular fibrillation, was at fault from the electrical discharge, cardiac arrest would be expected to occur at the Taser activation. However, if individuals were under the influence of sympathomimetic drugs such as cocaine, methamphetamine, or phencyclidine or were having the clinical presentation of excited delirium, other important clinically significant physiologic aberrations might contribute to these sudden deaths.
Because the metabolic and ventilatory effects of an acute Taser exposure are unknown in humans, the aim of this study was to investigate the extent of physiologic stress after exposure to the Taser X26. We monitored cardiorespiratory and blood characteristics in police officer volunteers before, during, and after a 5-second Taser exposure that was part of their police training. Because of the widespread and increasing use of Taser devices by law enforcement agencies, it is vital to assess whether its use on humans increases the risk of physiologic stress, ventilatory impairment, cardiac muscle damage, or sudden death.
Section snippets
Study Design and Selection of Participants
This was a prospective study evaluating healthy police volunteers drawn from the pool of San Diego County, CA, Sheriff’s officers who had already volunteered to have a Taser exposure as part of their tactical training. Inclusion criteria included subjects who were between 18 and 60 years of age. Before the study was conducted, each subject was screened by the physician investigators to ensure that he or she was free of acute illness or pregnancy that would prevent completion of the study; all
Characteristics of Study Subjects
A total of 42 sheriff’s officers volunteered to participate in the study. Thirty-two completed the study, which included 27 men and 5 women. Ten subjects screened out before consent and enrollment and did not participate (6 because of increased baseline systolic blood pressures, 1 with an abnormal baseline ECG result, and 3 for taking medications for hypertension or cardiac disease). Complete cardiorespiratory measurements and blood samples were obtained from all 32 participants for each
Limitations
There are several limitations to our study. Our subjects were generally healthy and free from chronic disease, and duration of the Taser activation in our study did not exceed a single 5-second activation, whereas individuals in the field often receive multiple shocks. Our subjects were also not under the influence of illicit stimulant drugs or in a state of agitated delirium.
Discussion
The Taser delivers energy through a sequence of dampened sine-wave current pulses, each lasting about 11 μs. This energy is reportedly neither pure alternating current nor pure direct current but probably akin to rapid-fire, low-amplitude, direct-current shocks.3 The power output of the device is 26 W, average 2-mA current, and a maximum of 50,000 V, which is reported to be below the threshold of ventricular fibrillation.2 Studies directly stimulating canine hearts with the Taser failed to
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2021, Forensic Science InternationalCitation Excerpt :A voluntary human study by VanMeenen [19] noted a minor decrease of tidal volume during the exposure. Other studies by Vilke [20], Ho [21] and Dawes [22] found a slight increase in breathing rate afterwards. However, from personal experience during human studies [23], the typical response of an exposed individual is either valsalva (holding of breath) or exhalation.
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Supervising editor: E. John Gallagher, MD
Author contributions: GMV and TCC conceived the project, were coprincipal investigators, and worked on protocol formulation. CMS, FWK, SDL, and TSN assisted with protocol refinement. KDB assisted with analysis. GMV, CMS, FWK, SDL, TSN, EMC, and TCC assisted with article preparation. EMC assisted with data management and statistical analysis. GMV, CMS, KDB, FWK, SDL, TSN, and TCC worked on data collection. GMV takes responsibility for the paper as a whole.
Funding and support: By Annals policy, all authors are required to disclose any and all commercial, financial, and other relationships in any way related to the subject of this article, that might create any potential conflict of interest. See the Manuscript Submission Agreement in this issue for examples of specific conflicts covered by this statement. This study was funded by the National Institute of Justice (2005-IJ-CX-K051).
Publication dates: Available online August 24, 2007.