Aspiration-related pneumonia after Taser exposure - A multiple causations mechanism

Arrest-related deaths in the context of Conducted Electrical Weapon (CEW) deployment are rare. The evaluation of such complex events is a challenge for the forensic scientist. We present a case of a 49-year old man, who was exposed to a Taser X26P during a confrontation with the police. He lost consciousness, vomited, aspirated and died after having been hospitalized for several days at the ICU. Based on the patient´s medical history, autopsy findings, witness testimonies, and reliable clinical and toxicological blood parameters, the most probable cause and mechanisms of his death are discussed. The present work demonstrates, based on one case report, the possibilities as well as limitations of forensic assessment in CEW-related deaths.

A comparison of three conducted electrical weapons in a surrogate swine cardiac safety model

We used a previously described methodology in a swine model to compare the relative cardiac safety of the Axon T7 Conducted Electrical Weapon (CEW), released in October of 2018, to two prior generations of Axon CEWs to include the X2 and the X26E. A total of 5 swine (252 total CEW exposures) were tested by alternating the three weapons at each chest exposure location. Our testing, using systemic hypotension as the quantitative surrogate for cardiac capture, demonstrated that the T7 and X2 were not statistically different. Both were superior, in terms of reduced hypotension during exposure, to the X26E. This study is important as it demonstrates that the newly released weapon is non-inferior to the X2 and superior to the X26E using this surrogate safety model. It is also important because it is the first study to examine the cardiac effects of simultaneous multi-bay exposures. Our prior study compared the X2 to the X26E but examined only single bay exposures from the X2. Lastly, we feel we have improved the methodology for studying the comparative cardiac effects of CEWs.

Validity of the small swine model for human electrical safety risks

Small swine are the most common model now used for electrical safety studies. Because of the significant anatomical and electrophysiological differences and the effect of animal size on the ventricular fibrillation (VF) threshold, there are concerns that these differences may exaggerate the risks of electrical devices to humans. We chose, as an illustrative and relevant example, swine studies of the TASER® conducted electrical weapon (CEW) as it has numerous published VF studies. We reviewed the published electrical swine safety studies for CEWs and compared them to finite element modeling studies, electrical safety standards, and epidemiological experience from field usage. We also compared the body weights of the swine to those of law enforcement arrest-related deaths. Studies of small swine exaggerate the risks of CEWs to humans. This conclusion may be extrapolated to suggest that the use of small swine for electrical safety studies should be questioned in general.

Investigation of Deaths Temporally Associated with Law Enforcement Apprehension

The investigation of a death that occurs in custody requires a careful and methodical approach since concerns of police or institutional misconduct may be raised. The medicolegal official charged with the investigation and ultimate certification of death bears heavy responsibility to the decedent's family, the public, law enforcement and other institutions. A wide variety of causes of death and manners of death are seen in these deaths. This paper reviews causes, mechanisms, manners, findings, and evaluation of persons who have died in temporal relation to legal apprehension.

Cardiac stimulation with electronic control device application

BACKGROUND

Electronic control devices (ECDs) are weapons used to incapacitate violent subjects. Subjects have died suddenly after ECD application, but because cardiac dysrhythmias have been inconsistently observed during ECD application in animals, the cause for death is uncertain.

OBJECTIVES

The objective was to identify the factors contributing to cardiac stimulation during ECD application detected by transesophageal echocardiography.

METHODS

Four Yorkshire pigs were anesthetized, paralyzed with vecuronium, and restrained in a supine position. A GE 6T echo probe was placed in the esophagus to directly visualize left ventricular function. M-mode echocardiography was used to estimate heart rate. Two dart locations, chest and abdomen, were assessed. ECD applications were delivered from one of five commercially available devices (Taser X26, Singer S200 AT, Taser M26, Taser X3, and Taser C2) in random order to each pig, four times in each orientation.

RESULTS

Cardiac stimulation, characterized by multiple PVCs or the sudden increase in ventricular contraction rate during application, did not occur with abdominal dart location. With chest dart application in small pigs, cardiac stimulation occurred with all ECDs except with the Taser X3 (p < 0.0001). In large pigs, cardiac stimulation occurred only during chest application of the S200 AT (chest vs. abdomen: 207 beats/min, vs. 91 beats/min, p < 0.0001).

CONCLUSION

Cardiac stimulation occurs during ECD application in pigs, and is dependent upon subject size, dart orientation, and ECD. The Taser X3 did not result in cardiac stimulation in small or large pigs.

Electrical safety of conducted electrical weapons relative to requirements of relevant electrical standards

INTRODUCTION

TASER(®) conducted electrical weapons (CEW) deliver electrical pulses that can inhibit a person's neuromuscular control or temporarily incapacitate. TASER X26, X26P, and X2 are among CEW models most frequently deployed by law enforcement agencies. The X2 CEW uses two cartridge bays while the X26 and X26P CEWs have only one. The TASER X26P CEW electronic output circuit design is equivalent to that of any one of the two TASER X2 outputs. The goal of this paper was to analyze the nominal electrical outputs of TASER X26, X26P, and X2 CEWs in reference to provisions of several international standards that specify safety requirements for electrical medical devices and electrical fences. Although these standards do not specifically mention CEWs, they are the closest electrical safety standards and hence give very relevant guidance.

METHODS

The outputs of two TASER X26 and two TASER X2 CEWs were measured and confirmed against manufacturer and other published specifications. The TASER X26, X26P, and X2 CEWs electrical output parameters were reviewed against relevant safety requirements of UL 69, IEC 60335-2-76 Ed 2.1, IEC 60479-1, IEC 60479-2, AS/NZS 60479.1, AS/NZS 60479.2 and IEC 60601-1. Prior reports on similar topics were reviewed as well.

RESULTS AND CONCLUSION

Our measurements and analyses confirmed that the nominal electrical outputs of TASER X26, X26P and X2 CEWs lie within safety bounds specified by relevant requirements of the above standards.

Sudden cardiac arrest and death following application of shocks from a TASER electronic control device

BACKGROUND

The safety of electronic control devices (ECDs) has been questioned. The goal of this study was to analyze in detail cases of loss of consciousness associated with ECD deployment.

METHODS AND RESULTS

Eight cases of TASER X26 ECD-induced loss of consciousness were studied. In each instance, when available, police, medical, and emergency response records, ECD dataport interrogation, automated external defibrillator information, ECG strips, depositions, and autopsy results were analyzed. First recorded rhythms were ventricular tachycardia/fibrillation in 6 cases and asystole (after ≈ 30 minutes of nonresponsiveness) in 1 case. An external defibrillator reported a shockable rhythm in 1 case, but no recording was made. This report offers evidence detailing the mechanism by which an ECD can produce transthoracic stimulation resulting in cardiac electrical capture and ventricular arrhythmias leading to cardiac arrest.

CONCLUSIONS

ECD stimulation can cause cardiac electrical capture and provoke cardiac arrest resulting from ventricular tachycardia/ventricular fibrillation. After prolonged ventricular tachycardia/ventricular fibrillation without resuscitation, asystole develops.

Defibrillation success rates for electrically-induced fibrillation: hair of the dog

Accidental electrocutions kill about 1000 individuals annually in the USA alone. There has not been a systematic review or modeling of elapsed time duration defibrillation success rates following electrically-induced VF. With such a model, there may be an opportunity to improve the outcomes for industrial electrocutions and further understand arrest-related-deaths where a TASER(®) electrical weapon was involved. We searched for MedLine indexed papers dealing with defibrillation success following electrically-induced VF with time durations of 1 minute or greater post VF induction. We found 10 studies covering a total of 191 experiments for defibrillation of electrically-induced VF for post-induction durations out to 16 minutes including 0-9 minutes of pre-shock chest compressions. The results were fitted to a logistic regression model. Total minutes of VF and use of pre-shock chest compressions were significant predictors of success (p &#60; .00005 and p= .003 respectively). The number of minutes of chest compressions was not a predictor of success. With no compressions, the 90% confidence of successful defibrillation is reached at 6 minutes and the median time limit for success is 9.5 minutes. However, with pre-shock chest compressions, the modeled data suggest a 90% success rate at 10 minutes and a 50% rate at 14 minutes.1.

Funding source and author affiliation in TASER research are strongly associated with a conclusion of device safety

BACKGROUND

Controversy exists regarding the safety of electrical stun guns (TASERs). Much of the research on TASERs is funded by the maker of the device and, therefore, could be biased. We sought to determine if funding source or author affiliation is associated with TASER research conclusions.

METHODS

MEDLINE was searched for TASER or electrical stun gun to identify relevant studies. All human and animal studies published up to September 01, 2010, were included. Reviews, editorials, letters, and case reports were excluded from the analysis. Two independent reviewers blinded to this study hypothesis evaluated each article with regard to conclusions of TASER safety.

RESULTS

Fifty studies were reviewed: 32 (64%) were human studies and 18 (36%) were animal studies. Twenty-three (46%) studies were funded by TASER International or written by an author affiliated with the company. Of these, 22 (96%) concluded that TASERs are unlikely harmful (26%) or not harmful (70%). In contrast, of the 22 studies not affiliated with TASER, 15 (55%) concluded that TASERs are unlikely harmful (29%) or not harmful (26%). A study with any affiliation with TASER International had nearly 18 times higher odds to conclude that the TASER is likely safe as compared with studies without such affiliation (odds ratio 17.6, 95% CI 2.1-150.1, P = .001).

CONCLUSIONS

Studies funded by TASER and/or written by an author affiliated with the company are substantially more likely to conclude that TASERs are safe. Research supported by TASER International may thus be significantly biased in favor of TASER safety.

A novel mechanism for electrical currents inducing ventricular fibrillation: The three-fold way to fibrillation

It has been long recognized that there are 2 methods for inducing VF (ventricular fibrillation) with electrical currents‥ These are: (1) delivering a high-charge shock into the cardiac T-wave, and (2) delivering lower level currents for 1-5 seconds. Present electrical safety standards are based on this understanding. We present new data showing a 3(rd) mechanism of inducing VF which involves the steps of delivering sufficient current to cause high-rate cardiac capture, causing cardiac output collapse, leading to ischemia, for sufficiently long duration, which then lowers the VFT (VF threshold) to the level of the current, which finally results in VF. This requires about 40% of the normal VF-induction current but requires a duration of minutes instead of seconds for the VF to be induced. Anesthetized and ventilated swine (n=6) had current delivered from a probe tip 10 mm from the epicardium sufficient to cause hypotensive capture but not directly induce VF within 5 s. After a median time of 90 s, VF was induced. This 3(rd) mechanism of VF induction should be studied further and considered for electrical safety standards and is relevant to long-duration TASER Electronic Control Device applications.

Ventricular fibrillation risk estimation for conducted electrical weapons: critical convolutions

The TASER® Conducted Electrical Weapon (CEW) is used by law enforcement agencies about 900 times per day worldwide and has been shown to reduce suspect and officer injuries by about 65%. However, since a CEW delivers rapid electrical pulses through injected probes, the risk of inducing ventricular fibrillation (VF) has been considered. Animal studies have shown that the tip of the probe must come within a few millimeters of the surface of the heart for the CEW to induce VF in a typical animal application. Early calculations of the CEW VF risk in humans used sophisticated 3-D chest models to determine the size of the probe landing areas that had cardiac tissue within a given distance of the inner surface of the ribs. This produced a distribution of area (cm(2)) vs. mm of depth. Echocardiography was then used to determine the shortest distance from the skin surface to the cardiac surface. This produced a population distribution of skin-to-heart (STH) distances. These 2 distributions were then convolved to arrive at a probability of inducing VF for a typical human CEW application. With 900, 000 probe-mode field uses to date, epidemiological results have shown that these initial VF risk estimates were significant overestimates. We present model refinements that take into account the gender and body-mass-index (BMI) of the target demographics and produce VF risk estimates concordant with the epidemiological results. The risk of VF is estimated at 0.4 per million uses with males.

Estimating the probability that the Taser directly causes human ventricular fibrillation

This paper describes the first methodology and results for estimating the order of probability for Tasers directly causing human ventricular fibrillation (VF). The probability of an X26 Taser causing human VF was estimated using: (1) current density near the human heart estimated by using 3D finite-element (FE) models; (2) prior data of the maximum dart-to-heart distances that caused VF in pigs; (3) minimum skin-to-heart distances measured in erect humans by echocardiography; and (4) dart landing distribution estimated from police reports. The estimated mean probability of human VF was 0.001 for data from a pig having a chest wall resected to the ribs and 0.000006 for data from a pig with no resection when inserting a blunt probe. The VF probability for a given dart location decreased with the dart-to-heart horizontal distance (radius) on the skin surface.

Effect of an electronic control device exposure on a methamphetamine-intoxicated animal model

OBJECTIVES

Because of the prevalence of methamphetamine abuse worldwide, it is not uncommon for subjects in law enforcement encounters to be methamphetamine-intoxicated. Methamphetamine has been present in arrest-related death cases in which an electronic control device (ECD) was used. The primary purpose of this study was to determine the cardiac effects of an ECD in a methamphetamine intoxication model.

METHODS

Sixteen anesthetized Dorset sheep (26-78 kg) received 0.0 mg/kg (control animals, n = 4), 0.5 mg/kg (n = 4), 1.0 mg/kg (n = 4), or 1.5 mg/kg (n = 4) of methamphetamine hydrochloride as a slow intravenous (IV) bolus during continuous cardiac monitoring. The animals received the following exposures in sequence from a TASER X26 ECD beginning at 30 minutes after the administration of the drug: 1) 5-second continuous exposure, 2) 15-second intermittent exposure, 3) 30-second intermittent exposure, and 4) 40-second intermittent exposure. Darts were inserted at the sternal notch and the cardiac apex, to a depth of 9 mm. Cardiac motion was determined by thoracotomy (smaller animals, < or = 32 kg) or echocardiography (larger animals, > 68 kg). Data were analyzed using descriptive statistics and chi-square tests.

RESULTS

Animals given methamphetamine demonstrated signs of methamphetamine toxicity with tachycardia, hypertension, and atrial and ventricular ectopy in the 30-minute period immediately after administration of the drug. Smaller animals (n = 8, < or = 32 kg, mean = 29.4 kg) had supraventricular dysrhythmias immediately after the ECD exposures. Larger animals (n = 8, > 68 kg, mean = 72.4) had only sinus tachycardia after the exposures. One of the smaller animals had frequent episodes of ventricular ectopy after two exposures, including runs of delayed onset, nonsustained six- to eight-beat unifocal and multifocal ventricular tachycardia that spontaneously resolved. This animal had significant ectopy prior to the exposures as well. Thoracotomy performed on three smaller animals demonstrated cardiac capture during ECD exposure consistent with previous animal studies. In the larger animals, none of the methamphetamine-intoxicated animals demonstrated cardiac capture. Two control sheep showed evidence of capture similar to the smaller animals. No ventricular fibrillation occurred after the exposure in any animal.

CONCLUSIONS

In smaller animals (32 kg or less), ECD exposure exacerbated atrial and ventricular irritability induced by methamphetamine intoxication, but this effect was not seen in larger, adult-sized animals. There were no episodes of ventricular fibrillation after exposure associated with ECD exposure in methamphetamine-intoxicated sheep.

Theoretical possibility of ventricular fibrillation during use of TASER neuromuscular incapacitation devices

INTRODUCTION

TASER devices deliver electrical pulses that temporarily incapacitate suspects. This study analyzes the theoretical possibility of ventricular fibrillation (VF) induction by TASER currents.

METHODS AND RESULTS

Using finite element models (FEM), the results found that the skin, fat and anisotropic skeletal muscle layers attenuated a large portion of TASER currents, allowing just a fractional amount to penetrate transversally into deeper layers of tissue. The TASER current density reached 91 mA/cm(2), the threshold required to induce VF, at less than 14.7 mm away from the skin surface. This distance is significantly lower than the average skin-heart distance of 35 mm, as measured in subjects with a body-mass index (BMI) matched to that of typical in-custody suspects. The theoretical probability of inducing VF is significantly lower than 0.0000008, or 1:1,270,000. By comparison, the standard for basic safety and essential performance of medical electrical equipment, EN 60601-1, accepts as satisfactory a VF induction probability of 0.002, or 1:500.

CONCLUSION

The results indicated that TASER devices, while not risk free, have a very low cardiac risk profile when used for suspect temporary incapacitation.

Cardiac effects of varying pulse charge and polarity of TASER conducted electrical weapons

The TASER(R) CEW (Conducted Electrical Weapon) is rapidly replacing the club in the English-speaking world for assisting in the arrest of resistant subjects and is now used by the majority of law enforcement agencies in the USA, Canada, and the UK. Animal safety studies of the CEW have focused on the risk of VF. We sought to determine the difference in cardiac capture and VF risk between the approximately 102 +/- 8 microC of the ubiquitous X26 and a me-tered 72 microC charge from an experimental device. It is well established from the bidomain theory and experimental data that a pacing electrode will capture the heart with significantly lower charge when the electrode touching the cardiac tissue is a cathode However, experimental data show that there is no difference in the ability of the anode vs the cathode to induce VF. We sought to evaluate the effect of polarity changes on cardiac capture and the induction of VF. Small swine ( approximately 20.0 kg) were anesthetized and ventilated. The apex of the heart was located via echocar-diography and a CEW probe was fully inserted towards the apex. Echocardiography was used to monitor cardiac contractions to determine cardiac capture. Both the X26 and the 72 microC pulses were delivered at both polarities to test for cardiac capture. Higher charge pulses (375 microC) were then delivered with both polarities to test for VF risk. The 72 microC experimental unit was unable to cause cardiac capture even in small swine with fully inserted probes directly over the apex of the heart. We found no polarity effect in the risk of VF in small swine with larger charge ( approximately 5x) pulses.