Original ContributionTwelve-lead electrocardiogram monitoring of subjects before and after voluntary exposure to the Taser X26
Introduction
It is estimated that 30% of US police agencies currently deploy the Taser (Taser International, Scottsdale, Ariz) [1]. Taser International has estimated that the Taser has been used on more than 150 000 volunteers and more than 100 000 “real-life” police confrontations. The actual number of uses is unknown. The manufacturer asserts that the device helps officers avoid the use of deadly force while lowering the risk of injury to officers, but there are few data to support that claim.
The Taser delivers energy through a sequence of dampened sine-wave current pulses each lasting approximately 11 microseconds. This energy is reportedly neither pure alternating current nor pure direct current but probably akin to rapid-fire, low-amplitude, direct-current shocks [2]. The power output of the device is 26 W, with an average 2 mA current and a maximum of 50 000 V. It is designed to be deployed to up to 7 m (21 ft) from the subject. The operator fires the handgun-shaped device, releasing 2 barbs with 1-cm tips attached to the device by thin 7-m copper wires. A 5-second electric pulse is automatically delivered through the wires to incapacitate the subject by causing involuntary tonic-clonic muscular contractions. The officer may deliver continued pulses by pulling the device trigger again. The barbs do not need to be touching or penetrating the subject's skin to be effective, as the electricity can penetrate up to 2 in of clothing.
Although the effects of the Taser on human subjects are incompletely studied, the Taser is generally regarded as safe [2], [3], [4]. However, most of the data supporting the product's approval by the US Consumer Product and Safety Commission were based on theoretical calculations and not on animal or human studies [5]. Most of the deaths reported in human subjects after receiving Taser activations are associated with illicit drug use, especially phencyclidine, in the 1980s [3], [6], [7].
Although previous data from the Police Executive Research Forum report that the average time from Taser activation to death in those individuals who died in custody after a Taser activation was 63 minutes, there is concern by some that the Taser activation could have an immediate effect on cardiac conductivity, such as prolonging the QT interval and placing the individual at risk for a sudden cardiac event. Our preliminary work using a single lead to monitor the heart before, during, and after a Taser activation demonstrated no dysrhythmias [8]. Attempts to calculate accurate QT, PR, and QRS intervals were challenging, as the interval durations could not reliably be determined from the single-lead monitoring. The present study was designed to use 12-lead electrocardiogram (ECG) monitoring to determine if a shock exposure from a Taser X26 results in changes in cardiac conduction in healthy police volunteers.
Section snippets
Materials and methods
This was a prospective study evaluating police volunteers undergoing exposure to a Taser X26 activation. The San Diego Police Department has purchased the new Taser X26 for use on the streets and has been training officers on its use. The training procedures for the San Diego Police Department include a training course that provides officers with an opportunity to be “hands on” with the Taser and experience a shock. Healthy adult research subjects were recruited from this pool of law
Results
During the study period, a total of 32 police officers and officers-in-training volunteered to participate in the experiment. In all cases, an interpretable 12-lead ECG was obtained before and after the Taser activation except for the post–PR interval for 1 subject. The missing ECG component had no effect on the remaining measures and was only excluded from the PR-interval calculations. Two (6%) subjects reported chronic or ongoing medical problems that included musculoskeletal and
Discussion
To date, there are only 3 prior studies that have looked at electrocardiac changes in humans immediately after a Taser activation [8], [10]. Two used single-lead monitoring to assess cardiac changes by monitoring immediately before, during, and for several seconds after a Taser activation. Both noted an increase in subject heart rate immediately before the activation and a slightly higher heart rate immediately afterward. No ectopy or dysrhythmias were noted in any of the subjects in any of the
Conclusion
In healthy police volunteers, we found no clinically significant changes in cardiac interval changes, including QTc, PR, or QRS immediately after a Taser activation.
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