Effect of an Electronic Control Device Exposure on a Methamphetamine‐intoxicated Animal Model

Abstract

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, £ 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, £ 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.ACADEMIC EMERGENCY MEDICINE 2010; 17:436-443 ª

Sudden Cardiac Arrest and Death Following Application of Shocks From a TASER Electronic Control Device

“…The threshold for transthoracic cardiac electrical capture is 100 microcoulombs, 10 which is the output of the TASER model X26. 1 Studies in pigs, [11][12][13][14][15] sheep, 16 and humans 17 established that transthoracic shocks from the TASER model X26 or a new prototype ECD 18 caused cardiac electrical capture. In addition, porcine research showed that such electrical capture could provoke VF at normal [12][13][14][15] or higher-than-normal 11 TASER model X26 outputs.…”

“…25 It is clear from the information cited above that an ECD shock to the chest can produce cardiac electrical capture at rapid rates in animals and humans. [11][12][13][14][15][16][17][18] Furthermore, it is clear that VF has been documented as early as 2 minutes after an ECD shock to humans. 3,5 What is lacking is the actual ECG recording of VF induction during an ECD shock in humans, a practical impossibility unless it fortuitously occurred in an individual with a recording device already in place.…”

“…12 In fact, in 1 porcine study, 13 ECD discharge induced a stable monomorphic VT that remained for Ϸ3 minutes before degeneration to VF. An example of recording an initial pulse and respiration immediately after ECD-induced loss of consciousness was given in the published New England Journal of Medicine letter 3 in which a paramedic, present during the entire ECD deployment, felt an initial pulse of 100 (counted for 15 seconds) and respirations of 16,5 with VF documented by ECG 2 minutes later. Normal breathing has been documented in pigs and sheep for a minute after the onset of ventricular fibrillation and in humans for at least the first 12-15 seconds.…”

Transcardiac Conducted Electrical Weapon (TASER) Probe Deployments: Incidence and Outcomes

“…Although some animal studies have noted no cardiac conduction effects of any kind, several investigators have observed myocardial capture, ventricular tachycardia, or ventricular fibrillation in these swine models using standard CEW output levels (12,18,23). Cocaine and methamphetamine have been administered in animal models without any observed episodes of induced ventricular dysrhythmias and a suggestion of protective effects; and epinephrine has also been used, with observation of two episodes of ventricular dysrhythmias (18,23,24). Studies comparing anterior thoracic discharges to dorsal or extra-thoracic discharges have determined that the latter are not at risk of producing cardiac dysrhythmias at normal outputs (16,18,19).…”

Authors’ Response

“…Dawes and Ho examined the effect of an EMI exposure on six Dorst (sic) sheep receiving a methamphetamine infusion. Cardiac rhythm effects were reported, but no QTc interval data . Again, the number of animals is too small to detect a small effect size, and obtaining sheep from a single breed line might prevent detection of animals exhibiting I Kr channel blockade.…”