TASER Research Articles

Are TASER guns really safe?

The use of TASER or stun guns has become increasingly popular among police agencies. They are proposed as an alternative non-lethal incapacitating device which can be used against aggressive or potentially violent individuals. It has been suggested that they produce no long-term medical problems. Such devices have been available to the police in the USA since the early 1980s, but have become more prevalent in the UK within the last few years. The police federation of the UK have stated that they want to further increase TASER availability to non-firearms officers in the field. If, as expected, the use of electrical guns becomes more common, there will no doubt be an increase in the number of victims presenting to the emergency department. Whether this is as a result of injuries secondary to being 'shot' or for removal of the electrical darts, medical practitioners will need to recognize the consequences, both short and long term, of such devices. Language: en

Tasers – less than lethal!

We report a case of potentially lethal injury associated with the use of Taser. A 42-year-old man was stopped by police for potential detention. He held a large carving knife over his epigasrium threatening to stab himself. With a view to achieving immobilisation, a Taser gun was used. On activation of the Taser, the subject suffered a 7-cm wide and 10-cm deep stab injury to the upper abdomen. In this case, activation of the Taser resulted in the contraction of skeletal muscles, flexors more intensely than extensors, resulting in the stab injury.

Generalized tonic-clonic seizure after a taser shot to the head

During a police chase on foot, a previously well police officer was hit mistakenly by a taser shot meant for the suspect. The taser gun had been fired once, sending 2 barbed darts into his upper back and occiput. Within seconds, the officer collapsed and experienced a generalized tonic-clonic seizure with loss of consciousness and postictal confusion. Subsequent magnetic resonance imaging scans of the head and electroencephalograms were normal. The patient has experienced no recurrence of seizure over more than a year of follow-up. This report shows that a taser shot to the head may result in a brain-specific complication such as generalized tonic-clonic seizure. It also suggests that seizure should be considered an adverse event related to taser use.

Acute effects of an alternative electronic-control-device waveform in swine

In previous studies, repeated 5-s exposures of anesthetized pigs to an electronic control device (TASER International's Advanced TASER X26 device) resulted in acidosis and increases in blood electrolytes. In the current study, experiments were performed to investigate the effects of longer continuous exposures to a different electronic-control-device waveform. After intramuscular injection of tiletamine HCl and zolazepam HCl, anesthesia was maintained with propofol infusion. Ten pigs were exposed to either 30- or 60-s applications of an electronic waveform similar to the TASER-X26 device. Transient increases in potassium, and sodium were consistent with previous reports in the literature dealing with studies of muscle stimulation or exercise. Blood pH was significantly decreased after exposure, but subsequently returned to baseline levels. Lactate was highly elevated and remained somewhat increased even after three hrs. Serum myoglobin was increased after exposure and remained elevated for the 3-h follow-up period. Acidosis would appear to be one of the major concerns with long-duration (e.g., several min) exposures over a short period of time. Even with the extremely low pH immediately after exposure, all animals survived. On the basis of these results, further development of useful continuous-exposure electronic control devices is at least feasible, with the caveat that some medical monitoring of subjects may be required.

Safety of pulsed electric devices

The strength–duration curve for tissue excitation can be modeled by a parallel resistor–capacitor circuit that has a time constant. We tested several short-duration electric generators: five electric fence energizers, the Taser X26 and a high-frequency generator to determine their current-versus-time waveforms. We estimated their safety characteristics using existing IEC and UL standards for electric fence energizers. The current standards are difficult to follow, with cumbersome calculations, and do not explicitly explain the physiological relevance of the calculated parameters. Hence we propose a new standard. The proposed new standard would consist of a physical RC circuit with a certain time constant. The investigator would discharge the device into a passive resistor–capacitor circuit and measure the resulting maximum voltage. If the maximum voltage does not exceed a limit, the device passes the test.

Taser X26 Discharges in Swine: Ventricular Rhythm Capture is Dependent on Discharge Vector

Data from our previous studies indicate that Taser X26 stun devices can acutely alter cardiac function in swine. We hypothesized that most transcardiac discharge vectors would capture ventricular rhythm, but that other vectors, not traversing the heart, would fail to capture the ventricular rhythm. Using an Institutional Animal Care and Use Committee (IACUC) approved protocol, four Yorkshire pigs (25-36 kg) were anesthetized, paralyzed with succinylcholine (2 mg/kg), and then exposed to 10 second discharges from a police-issue Taser X26. For most discharges, the barbed darts were pushed manually into the skin to their full depth (12 mm) and were arranged in either transcardiac (such that a straight line connecting the darts would cross the region of the heart) or non-transcardiac vectors. A total of 11 different vectors and 22 discharge conditions were studied. For each vector, by simply rotating the cartridge 180-degrees in the gun, the primary current-emitting dart was changed and the direction of current flow during the discharge was reversed without physically moving the darts. Echocardiography and electrocardiograms (ECGs) were performed before, during, and after all discharges. p values < 0.05 were considered significant. ECGs were unreadable during the discharges because of electrical interference, but echocardiography images clearly demonstrated that ventricular rhythm was captured immediately in 52.5% (31 of 59) of the discharges on the ventral surface of the animal. In each of these cases, capture of the ventricular rhythm with rapid ventricular contractions consistent with ventricular tachycardia (VT) or flutter was seen throughout the discharge. A total of 27 discharges were administered with transcardiac vectors and ventricular capture occurred in 23 of these discharges (85.2% capture rate). A total of 32 non-transcardiac discharges were administered ventrally and capture was seen in only eight of these (25% capture rate). Ventricular fibrillation (VF) was seen with two vectors, both of which were transcardiac. In the remaining animals, VT occurred postdischarge until sinus rhythm was regained spontaneously. For most transcardiac vectors, Taser X26 caused immediate ventricular rhythm capture. This usually reverted spontaneously to sinus rhythm but potentially fatal VF was seen with two vectors. For some non-transcardiac vectors, capture was also seen but with a significantly (p < 0.0001) decreased incidence.

The neuroendocrine effects of the TASER X26 ®: A brief report

Introduction Law enforcement officers use conducted electrical weapons (CEW) such as the TASER X26 ® to control violently resistive subjects. There are no studies in the medical literature examining the effects of these weapons on the human stress response. This is the first study to compare the human stress response to conducted electrical weapons, oleoresin capsicum (O.C.), a cold-water tank immersion, and a defensive tactics drill. Methods Subjects were randomized to one of the four interventions studied. Subjects received either a 5-s exposure from the TASER X26 CEW with the probes fired into the back from 7 ft, a 5-s spray of O.C., a skin and mucous membrane irritant, to the eyes, a 45-s exposure of the hand and forearm in a 0 °C cold water tank, or a 1-min defensive tactics drill. Results Alpha-amylase had the greatest increase from baseline at 10–15 min with the defensive tactics drill. Cortisol had the greatest increase at 15–20 min with O.C. Cortisol remained most elevated at 40–60 min in the defensive tactics drill group. Conclusions Our preliminary data suggests that physical exertion during custodial arrest may be most activating of the human stress response, particularly the sympathetic–adrenal–medulla axis. This may suggest that techniques to limit the duration of this exertion may be the safest means to apprehend subjects, particularly those at high-risk for in-custody death. Conducted electrical weapons were not more activating of the human stress response than other uses of force.

TASER safety

TASER safety

75: The Effect of a Cross-Chest Electronic Control Device Exposure on Breathing

A previous study examined the effects of a unilateral thoraco-abdominal exposure from a TASER X26 on breathing and found no adverse effects at 15 seconds. This study, combined with a study demonstrating normal diaphragmatic excursion with an ipsilateral exposure, provided strong evidence for a lack of respiratory impairment from the device. However, an exposure transversely across the chest had not been previously studied.

Echocardiographic Evaluation of a TASER‐X26 Application in the Ideal Human Cardiac Axis

TASER electronic control devices (ECDs) are used by law enforcement to subdue aggressive persons. Some deaths temporally proximate to their use have occurred. There is speculation that these devices can cause dangerous cardiac rhythms. Swine research supports this hypothesis and has reported significant tachyarrhythmias. It is not known if this occurs in humans. The objective of this study was to determine the occurrence of tachyarrhythmias in human subjects subjected to an ECD application. This was a prospective, nonblinded study. Human volunteers underwent limited echocardiography before, during, and after a 10-second TASER X26 ECD application with preplaced thoracic electrodes positioned in the upper right sternal border and the cardiac apex. Images were analyzed using M-mode through the anterior leaflet of the mitral valve for evidence of arrhythmia. Heart rate (HR) and the presence of sinus rhythm were determined. Data were analyzed using descriptive statistics. A total of 34 subjects were enrolled. There were no adverse events reported. The mean HR prior to starting the event was 108.7 beats/min (range 65 to 146 beats/min, 95% CI = 101.0 to 116.4 beats/min). During the ECD exposure, the mean HR was 120.1 beats/min (range 70 to 158 beats/min, 95% CI = 112.2 to 128.0 beats/min) and a mean of 94.1 beats/min (range 55 to 121 beats/min, 95% CI = 88.4 to 99.7 beats/min) at 1 minute after ECD exposure. Sinus rhythm was clearly demonstrated in 21 (61.7%) subjects during ECD exposure (mean HR 121.4 beats/min; range 75 to 158 beats/min, 95% CI = 111.5 to 131.4). Sinus rhythm was not clearly demonstrated in 12 subjects due to movement artifact (mean HR 117.8 beats/min, range 70 to 152 beats/min, 95% CI = 102.8 to 132.8 beats/min). A 10-second ECD exposure in an ideal cardiac axis application did not demonstrate concerning tachyarrhythmias using human models. The swine model may have limitations when evaluating ECD technology.

In Reply

In Reply

Pharyngeal perforation secondary to electrical shock from a Taser gun

The case history is presented of a patient who developed pharyngeal perforation following the use of a Taser electroshock gun. This complication has not previously been reported.

Uncommon Cause of Death: The Use of Taser Guns in South Florida

Uncommon Cause of Death: The Use of Taser Guns in South Florida

TASER X26 Discharges in Swine Produce Potentially Fatal Ventricular Arrhythmias

Data from the authors and others suggest that TASER X26 stun devices can acutely alter cardiac function in swine. The authors hypothesized that TASER discharges degrade cardiac performance through a mechanism not involving concurrent acidosis. Using an Institutional Animal Care and Use Committee (IACUC)-approved protocol, Yorkshire pigs (25-71 kg) were anesthetized, paralyzed with succinylcholine (SCh; 2 mg/kg), and then exposed to two 40-second discharges from a TASER X26 with a transcardiac vector. Vital signs, blood chemistry, and electrolyte levels were obtained before exposure and periodically for 48 hours postdischarge. Electrocardiograms and echocardiography (echo) were performed before, during, and after the discharges. p-Values < 0.05 were considered significant. Electrocardiograms were unreadable during the discharges due to electrical interference, but echo images showed unmistakably that cardiac rhythm was captured immediately at a rate of 301 +/- 18 beats/min (n = 8) in all animals tested. Capture continued for the duration of the discharge and in one animal degenerated into fatal ventricular fibrillation (VF). In the remaining animals, ventricular tachycardia (VT) occurred postdischarge for 1-17 seconds, whereupon sinus rhythm was regained spontaneously. Blood chemistry values and vital signs were minimally altered postdischarge and no significant acidosis was seen. Extreme acid-base disturbances usually seen after lengthy TASER discharges were absent with SCh, but TASER X26 discharges immediately and invariably produced myocardial capture. This usually reverted spontaneously to sinus rhythm postdischarge, but fatal VF was seen in one animal. Thus, in the absence of systemic acidosis, lengthy transcardiac TASER X26 discharges (2 x 40 seconds) captured myocardial rhythm, potentially resulting in VT or VF in swine.

Twelve-lead electrocardiogram monitoring of subjects before and after voluntary exposure to the Taser X26

Objectives The Taser (Taser International, Scottsdale, Ariz) uses high-voltage electricity to incapacitate subjects. We sought to evaluate cardiac rhythm changes during deployment of the Taser on healthy volunteers. Methods This prospective study was performed on 32 healthy volunteer subjects receiving a Taser X26 discharge. The subjects had baseline 12-lead electrocardiogram (ECG) monitoring performed immediately before and within 1 minute after the Taser discharge. Changes in cardiac rhythm, morphology, and interval duration were evaluated. Descriptive statistics and paired-sample t test comparisons are reported. Results All 32 subjects had an interpretable 12-lead ECG obtained before and after the Taser activation, although 1 subject's post–PR interval could not be determined. The mean age and body mass index were 33 years and 26.5 kg/m 2, respectively. Overall, there was a significant increase in heart rate (2.4; 95% confidence interval [CI], 0.0-4.9) and a decrease in PR interval (−6.5; 95% CI, −9.7 to −3.3). When stratified by sex, only the PR interval in men significantly decreased (−5.9; 95% CI, −9.2 to −2.5). There were significant changes in heart rate (4.0; 95% CI, 1.3-6.7), PR interval (−6.0; 95% CI, −11.3 to −0.7), and QT interval (−18.8; 95% CI, −33.2 to −4.3) among those with a normal body mass index, and in PR interval among those who were overweight/obese (−6.7; 95% CI, −10.8 to −2.5). None of the statistically significant differences between ECG measures were clinically relevant. Conclusions There were no cardiac dysrhythmia and interval or morphology changes in subjects who received a Taser discharge based on a 12-lead ECG performed immediately before and within 1 minute after a Taser activation.

How a Taser Works

The Taser gun, an electroshock weapon used by police departments worldwide is no stranger to bad press. Any new technology that is designed for violent encounters should be carefully assessed. Unlike medical devices, Tasers don't have to undergo testing and receive approval by agencies such as the U.S. Food and Drug Administration, at least not in the United States. Partly in response, several local and state legislatures have considered introducing laws restricting the stun guns' adoption, and most police departments, if not all, have instituted guidelines on the proper use of Tasers. Equipping law-enforcement services with Tasers is likely to reduce the number of bullets officers fire from their handguns and therefore the number of serious injuries and deaths. At the same time, it may lead police to inflict an unwarranted amount of pain on individuals who commit only minor crimes.

15-Second conducted electrical weapon exposure does not cause core temperature elevation in non-environmentally stressed resting adults

Introduction Conducted electrical weapons (CEW) are being incorporated into the use of force continuums of law enforcement agencies in increasing numbers. The use of these weapons has been controversial, especially as related to the sudden in-custody death (ICD) phenomenon. Hyperthermia has been reported in many ICDs attributed to excited delirium, illicit drug toxicity, or other causes. There is speculation that the electrical discharge from the CEWs may contribute to the hyperthermia, presumably from muscle tetany-induced thermogenesis. The objective of this study was to investigate the effect of a prolonged discharge of a CEW on core body temperature in human subjects. Methods This was a prospective, observational study of non-environmentally stressed resting adult human volunteers. Volunteers were exposed to a 15-s continuous discharge from a TASER X26 ® CEW. A control group conducted usual activities of daily living (ADLs). Core body temperature was measured every 15 s by a swallowed telemetric temperature measuring device. Descriptive statistics were applied. Results 31 subjects were enrolled. 17 subjects received the TASER X26® CEW exposure, and 10 subjects carried out usual ADLs as controls. The discharge from the TASER X26® CEW did not cause an elevation in core body temperature. The range in temperatures among all subjects was 33.1–38.3 °C, mean 36.7 + 0.6. The mean temperature 1 min after exposure was 37.4 + 0.4. There was no change in temperature from 1 min before the exposure to 1 min, 10 min, or 20 min after the exposure in the majority of patients. One patient had a 0.2 degree increase at 20 min, three patients had a 0.1 degree decrease in temperature at 10 min or 20 min. The mean temperature for subjects in the control group was 37.1, 95% CI = 36.9–37.3, and the mean for subjects in the exposed group was 36.7, 95% CI = 36.4–37.1. Conclusion A 15-s discharge from a TASER X26 ® CEW does not increase the core body temperature of resting, non-environmentally stressed adult subjects. These results challenge the speculation that this weapon technology may be contributing to the hyperthermia in subjects who die from excited delirium, drug toxicity, or other causes while in custody.

Can the Direct Cardiac Effects of the Electric Pulses Generated by the TASER X26 Cause Immediate or Delayed Sudden Cardiac Arrest in Normal Adults?

There is only a small amount of experimental data about whether the TASER X26, a nonlethal weapon that delivers a series of brief electrical pulses to cause involuntary muscular contraction to temporarily incapacitate an individual, can initiate ventricular fibrillation to cause sudden cardiac arrest either immediately or sometime after its use. Therefore, this paper uses the fundamental law of electrostimulation and experimental data from the literature to estimate the likelihood of such events. Because of the short duration of the TASER pulses, the large duration of the cardiac cell membrane time constant, the small fraction of current from electrodes on the body surface that passes through the heart, and the resultant high pacing threshold from the body surface, the fundamental law of electrostimulation predicts that the TASER pulses will not stimulate an ectopic beat in the large majority of normal adults. Since the immediate initiation of ventricular fibrillation in a normal heart requires a very premature stimulated ectopic beat and the threshold for such premature beats is higher than less premature beats, it is unlikely that TASER pulses can immediately initiate ventricular fibrillation in such individuals through the direct effect of the electric field generated through the heart by the TASER. In the absence of preexisting heart disease, the delayed development of ventricular fibrillation requires the electrical stimuli to cause electroporation or myocardial necrosis. However, the electrical thresholds for electroporation and necrosis are many times higher than that required to stimulate an ectopic beat. Therefore, it is highly unlikely that the TASER X26 can cause ventricular fibrillation minutes to hours after its use through direct cardiac effects of the electric field generated by the TASER.

Acute Effects of TASER X26 Discharges in a Swine Model

Very little objective laboratory data are available describing the physiologic effects of stun guns or electromuscular incapacitation devices (EIDs). Unfortunately, there have been several hundred in-custody deaths, which have been temporally associated with the deployment of these devices. Most of the deaths have been attributed to specific cardiac and metabolic effects. We hypothesized that prolonged EID exposure in a model animal system would induce clinically significant metabolic acidosis and cardiovascular disturbances. Using an Institutional Animal Care and Use Committee-approved protocol, 11 standard pigs (6 experimentals and 5 sham controls) were anesthetized with ketamine and xylazine. The experimentals were exposed to two 40-second discharges from an EID (TASER X26, TASER Intl., Scottsdale, AZ) across the torso. Electrocardiograms, blood pressure, troponin I, blood gases, and electrolyte levels were obtained pre-exposure and at 5, 15, 30, and 60 minutes and 24, 48, and 72 hours postdischarge. p values <0.05 were considered significant. Two deaths were observed immediately after TASER exposure from acute onset ventricular fibrillation (VF). In surviving animals, heart rate was significantly increased and significant hypotension was noted. Acid-base status was dramatically affected by the TASER discharge at the 5-minute time point and throughout the 60-minute monitoring period. Five minutes postdischarge, central venous blood pH (6.86 +/- 0.07) decreased from baseline (7.45 +/- 0.02; p = 0.0004). Pco2 (94.5 mm Hg +/- 14.8 mm Hg) was significantly increased from baseline (45.3 mm Hg +/- 2.6 mm Hg) and bicarbonate levels significantly decreased (15.7 mmol/L +/- 1.04 mmol/L) from baseline (30.4 mmol/L +/- 0.7 mmol/L). A large, significant increase in lactate occurred postdischarge (22.1 mmol/L +/- 1.5 mmol/L) from baseline (1.5 mmol/L +/- 0.3 mmol/L). All values returned to normal by 24 hours postdischarge in surviving animals. A minor, nonsignificant increase in troponin I was seen at 24 hours postdischarge (0.052 ng/mL +/- 0.030 ng/mL, mean +/- SEM). Immediately after the discharge, two deaths occurred because of ventricular fibrillation. In this model of prolonged EID exposure, clinically significant acid-base and cardiovascular disturbances were clearly seen. The severe metabolic and respiratory acidosis seen here suggests the involvement of a primary cardiovascular mechanism.

423: Breathing Parameters, Venous Blood Gases, and Serum Chemistries With Exposure to a New Wireless Projectile Conducted Electrical Weapon in Human Volunteers

The TASER X26 conducted electrical weapon (CEW) has a maximum range of 35 feet, limiting its effectiveness in some tactical situations. TASER International has developed a non-tethered CEW that is fired from a 12-gauge shotgun that has a longer range. A previous study showed that the TASER X26 had no significant effect on tidal volume, respiratory rate, PETCO2, and PETO2. The purpose of this study was to study the effects of this new CEW on respiration, venous blood gases, and certain blood chemistries.