THE RELATIVE IMMUNITY OF THE SKIN AND CARDIOVASCULAR SYSTEM TO THE DIRECT EFFECTS OF HIGH VOLTAGE - HIGH FREQUENCY COMPONENT ELECTRICAL PULSES.

Abstract - This paper summarizes our testing to date of commercially available battery powered hand held electric pulse generators, sometimes called TASER's, stun guns, or Less Than Lethal Weapons (LTLW). We present the generalized electronic properties of these devices along with physiologic effects on human and animal subjects.

The objectives of this work fall into two primary categories:

1. To characterize by physical measurements the electrical emissions from a representative cross section of commercially available battery powered hand held electric pulse generators whose primary application is in effecting non-lethal compliance and control of persons (or animals) whose manifest or latent behavior constitutes a perceived threat to the safety and well being of the holder of such a device; and

2. To further characterize by physiologic testing the biologic interactions of such emissions as they may effect the safety and effectiveness of such devices in the hands of their holders when such devices are used both in the prescribed manner as well as certain unexpected ways in healthy and previously sensitized individuals.

1. Physical Measurements: Most of the devices tested were designed to generate a default arcing condition in the air gap between closely spaced opposing interior projections of the two principal forward facing output terminals which are spaced 50 mm apart. Such arcs only occur when the output transformers feeding the terminals are electrically unloaded and peak potential across the interior probes exceeds the dielectric breakdown value of the air gap. Contacting the skin with the forward probes under almost any orientation or pressure and with virtually any topical condition of the skin significantly loads the output transformer resulting in a lowered output voltage which extinguishes arcing. A 20,000 dummy test load composed of twenty 1000 one watt resistors in series was used in all the testing. Graphic recordings were taken with a Model 2654 Tektronics oscilloscope operating in the differential mode. The probes were placed across a 20 resistor in the center of the test load providing a differential voltage divider factor of 1000. Further voltage division was accomplished using the scope attenuation controls. The battery powered pulse generator under test was entirely self-contained with no ground reference.

2. Physiologic Measurements:

a. Skin - Twenty 21-50 year old male police officer volunteers were exposed to 3 second bursts of the pulse generator output delivered to the volar aspect of one forearm. A non-electric pressure injury of a similar degree was applied to the contralateral arm. These sessions took place during regularly scheduled training programs specifically related to familiarization with the devices. Color photographs of the exposed sites were taken at 1 and 10 minutes post shock and again at 24 hours.

b. Cardiovascular System - Two 60 Kg Hampshire gilts were anesthetized with 20mg/Kg of Ketamine and supported under 5% Halothane and O2 anesthesia. Venous bipolar pacing catheters were placed in the right ventricle under fluoroscopic control. Twenty shocks of 3-5 seconds each were delivered to the endocardium by passing pulses from the two terminals of the pulse generator to the pacing leads of the catheter. Arterial blood pressure and surface EKG were recorded before, during, and after the application of the pulses.

1. Physical measurements: Units from 5 different device companies were tested. Listed in random order these manufacturers were:

a. Ultron - 2 models

b. Omega - 2 models

c. Nova - 1 model

d. U.S. Protector - 1 model

e. Guardian - 1 model

Some features common to all devices:

1. Pulse repetition rate, 5 to 25 Pulses Per Second

2. A single transistor relaxation oscillator with internal etched PCB spark gap, driving a high ratio ferrite stepup transformer.

3. Charging capacitors ranging 0.2 to 0.6 mfd.

4. One or two 9v battery power source.

Some features unique among devices:

1. One with a very high voltage output capacitor (not the charging capacitor) across the output transformer yeilding resonance enhancement.

2. One with hermetically sealed internal spark gap.

3. One with 30% lower output impedance than the average of the others.

4. One with loaded peak voltage 3.5 times the lowest.

2. Physiologic measurements

a. Skin - All twenty subjects exhibited the typical "signature response", specifically a punctate reddening of the skin at 10 minutes post shock limited to a 3-5mm diameter circle directly under each probe. Five out of 20 showed small wheals at the stimulus site. All of these hive-like elevations had disappeared at 1 to 2 hours. Only one case, a man of mediterranean ancestry, showed residual markings at 24 hours and these were gone in 2 days. No burns or other permanent markings were ever noted.

b. Cardiovascular - One device with 50kv output peak potential was used to deliver ten 3-5 second bursts to the pig's endocardium. In no case was there any evidence of alteration in the heart rhythm, or significant blood pressure variations occurring during or after the bursts.

Finally, these same tests were repeated in the presence of 1mg of epinephrine administered IV. The expected elevation of blood pressure and heart rate occurred in each case, but without any evidence of sensitization to the effects of the endocardial stimulus. No malignant rhythms or their progenitors were ever seen.

Although little has been published in the medical or bioengineering literature on subject of less than lethal weapons (LTLW's), the U.S. federal government has had a keen interest in the subject since the Johnson administration [1]. This interest was renewed in the mid 80's with a special symposium on the subject sponsored by the U.S. Dept. of Justice [2]. Bernstein [3] in the mid 70's attempted to characterize the TASER, a ballistic counterpart to the hand held devices, in terms of the 60Hz equivalent energy delivered to a subject. He updated his treatment of the subject to include certain hand held devices in 1985 [4]. Stratbucker [5] reported the first animal studies involving LTLW's in the bioengineering literature in 1986. Most recently Roy, et. al., [6] have published a report describing apparent ventricular fibrillation associated with the direct epicardial application of a stun gun to exposed pig hearts. This work appears to draw on prior work from the Canadian group related to high frequency transients encountered in the electric power industry. Our study appears to be at some variance with the Canadian group's work. The difference may lie in the dissimilar current density patterns associated with differing application techniques. To our knowledge no one has ever demonstrated an arrhythmic effect of LTLW's when applied anywhere on the exterior of the body, human or otherwise.

[1] Natl. Comm. on Causes & Prevention of Violence, U.S. Govt. Printing Office, Wash. D.C., 1969

[2] Atty. Gen. Conf. on LTLW, U.S. Dept. Justice Report, FBI Academy, June 11-12 1986

[3] T. Bernstein, "Lethality evaluation for the TASER Electric Gun", AAMI Ann. Meeting, March 1978

[4] T. Bernstein, "Evaluation of the Electric Shock Hazard for the NOVA XR 5000 Stun Gun", Madison WI, 1985

[5] R.A. Stratbucker, "The assesment of potential cardiac hazards in the use of hand-held electronic law enforcement devices", Proc. 8th Ann. Conf. IEEE Eng. Med. & Bio. Soc., Nov. 1986

[6] O.Z.Roy, A.S.Podgorski, "Tests on a shocking device - the stun gun", Med. & Bio. Eng. & Comp., 27, 445-448, 1989