Cardiac Safety of Neuromuscular Incapacitating Defensive Devices

Abstract

Neuromuscular incapacitation (NMI) devices discharge a pulsed dose of electrical energy to cause muscle contraction and pain. Field data suggest electrical NMI devices present an extremely low risk of injury. One risk of delivering electricity to a human is the induction of ventricular fibrillation (VF). We hypothesized that inducing VF would require a significantly greater NMI discharge than a discharge output by fielded devices. The cardiac safety of NMI discharges was studied in nine pigs weighing 60 +/- 28 kg. The minimum fibrillating level was defined as the lowest discharge that induced VF at least once, the maximum safe level was defined as the highest discharge which could be applied five times without VF induction, and the VF threshold was defined as their average. A safety index was defined as the ratio of the VF threshold to the standard discharge level output by fielded NMI devices. A VF induction protocol was applied to each pig to estimate the VF threshold and safety index. The safety index for stored charge ranged from 15X to 42X as weight increased from 30 to 117 kg (P < 0.001). Discharge levels above standard discharge and weight were independently significant for predicting VF inducibility. The safety index for an NMI discharge was significantly and positively associated with weight. Discharge levels for standard electrical NMI devices have an extremely low probability of inducing VF.

Deaths in custody: Are some due to electronic control devices (including TASER® devices) or excited delirium?

“…McDaniel et al 40 reported only minor fluctuations in blood pressure of swine exposed to an ECD. The authors hypothesized that the fluctuations were caused by mechanical contractions of skeletal muscles, with no cardiac involvement.…”

“…Investigators have reported no ventricular fibrillation associated with waveforms matching the TASER X26 ECD (e.g., McDaniel et al), 40 even with the probes positioned in close proximity along the cardiac axis. 41 Wu et al, 42 on the basis of experimentation using swine, estimated an extremely low likelihood of ECD darts landing in a manner to cause ventricular fibrillation in humans (probability of 0.000172).…”

“…The author has not had any relationship with any manufacturers of electronic control devices, including employment, consultan- 40,41 and considered unlikely, 42 particularly as direct effect. 45,46 Cases reported in ketamine/xylazine-anesthetized animals.…”

TASER safety

“…In addition, the threshold for ventricular fibrillation is directly related to body weight for both utility waveforms and electronic control device waveforms. 4,7 In humans, even if the barbs of an electronic control device are placed directly on the cardiac axis, no effect is captured with echocardiographic monitoring. 8 Third, it is erroneous to imply that electronic control devices can cause dangerous acidosis.…”

Mathematical framework for current density imaging due to discharge of electro-muscular disruption devices

“…See [3,6,11,13,14,29]. Numerous investigations on the implications of EMD shocks are, therefore, requested to create a guidance that helps device users to minimize the risk of injury or fatality of victims.…”