New conducted electrical weapons: Finite element modeling of safety margins

Introduction-We have previously published on the ventricular fibrillation (VF) risk with TASER
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X26 conducted electrical weapon (CEW). Our risk model accounted for realistic body mass index distributions, modeled the effects of partial or oblique dart penetration, and used epidemiological CEW statistics. As new CEWs have become available to law enforcement, their cardiac safety profile was not quantified. Therefore, we applied our VF probability model to evaluate their cardiac risk. Methods and Results-An eXperimental Rotating-Field (XRF) waveform CEW and the X2 CEW are new 2-shot electrical weapon models designed to target a precise amount of delivered charge per pulse, 64 μC and 62 μC, respectively. They can deploy 1 or 2 probe pairs, delivered by 2 separate cartridges. New Smart Probes (SP), which carry 11.5 mm long CEW darts, can be used with XRF and X2 CEWs. Finite element modeling (FEM) was used to approximate the current and charge densities produced by XRF and X2 CEWs in tissues located in the vicinity of darts, including accounting for the effects of fat, anisotropic skeletal muscles, sternum, ribs, and lungs. Using our previous cardiac risk probabilistic model, the new XRF and X2 CEWs operated with 11.5 mm SPs, had an estimated overall theoretical VF risk of less than 1 in 1 300 000 and 1 in 1 490 000 cases, respectively. We also found that the XRF and X2 CEWs had increased cardiac safety margins with respect to those previously reported for the X26 CEWs when all three CEW models were operated with 9 mm CEW darts. Lastly, the cardiac risk of these new CEWs (<; 0.76 ppm) was found to be much lower than reported levels of CEW non-cardiac fatal injuries (e.g. falls and burns, > 7.2 ppm). Conclusions-While not risk-free, the new TASER XRF and X2 CEWs offer increased cardiac safety margins and extremely low cardiac risk profiles.