Electric Shock on Venomous Bites & Stings

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use of Electric Shock for Snake & Spider Bites

And Scorpion & Bee Stings, please contact us at:

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Introduction

For over 60 years electric shock has been used as first aid in treating venomous bites and stings in Third World countries. Using the spark plug wire of an internal combustion engine to treat scorpion stings is a folkloric remedy that dates back to at least the 1940s [1]. Later, in the 80's and 90's, first aid shock therapy studies were published regarding snake by Guderian[2] and Mueller[3] [4] and spider bites by Osborn [5][6][7][8] . When no medical facilities nor antivenom are accessible, first aid electric shock has been touted as an acceptable alternative. However an adequate source and method of delivering the shock still remains a challenge.

In regard to stun guns as a source of HV shock, the design, quality, expense and effectiveness varies considerably between models. The published study of McPartland[9] successfully used a US built Nova-Spirit 40Kv stun gun. However, in a study done by Barrett[10], neither the Parali/azer stun nor the Guardian brand stun guns (both in excess of 100Kv) proved to have any affect on simulated brown recluse spider bites in Hartley guinea pigs. In fact, the Parali/azer delayed wound healing and resulted in significantly larger areas of induration when compared to untreated animals. This would be consistant with tissue damage caused by greatly excessive voltage for long shock periods. According to Roy and Podgorski [11] shock applied for more than 2 seconds can incapacitate the patient. Global statements concerning the safety of stun gun devices cannot be confidently made because the devices have been insufficiently tested, exhibit considerable intragun and intergun variability, and tend to malfunction frequently. [20][21]. Over 7000 stun guns were sold prior to the Food and Drug Administration banning the advertising of stun guns for the treatment of bites and stings in April 1990. Stun guns, although previously advertised for the treatment of venomous bites or stings, have never been licensed by the Food and Drug Administration for the treatment of any medical condition.[26]

Anecdotal use of stun guns and cattle prods has indicated that the low voltage cattle prods and low powered stun guns below 75kv, obtain results in regards to snake bite, where high voltage stun guns, in excess of ~100Kv, may not show results. The higher voltage of the high powered stun guns does not seem to neutralize the venom properly, this could explain some of the failed studies..

Mechanical solutions such as the spark generated by lawn mowers and vehicles have had positive results[2] [22][3] but have had their obvious limitations. Hand crank generators such as the Wade Machine are difficult to manufacture, bulky and expensive. A recent portable mechanical spring design looks promising.

As with many naturopathic remedies, the established medical community has been skeptical and none of their studies have showed positive results[12][13][14][15][16][17][18][19]. All of the studies available to date have their limitations. One major recurring concern of shock therapy advocates is that no human subjects were used, only laboratory animals. Venom Shock supporters question whether using an animal (mice and rats) that venomous snakes normally prey on is an appropriate model. Snake venom is designed to jump start the digestive process on prey, even before it has been swallowed. Other recurring concerns involve the type (fresh vs commercially available), source (species), and dose of venom administered in the controlled trials.

Recent Research

Recent, yet to be published research, shows there is a striking difference between morbid sequelae for patients receiving conventional treatment and for the patients receiving the electroshock treatment. The effectiveness of electroshock treatment of snakebites is clearly shown by the clinical data. In addition there is a good correlation between the promptness of treatment and speed of recovery.

The most striking results have been obtained by researchers at Hospital Vozandes in Ecuador where electrical treatment of snakebite is a government-endorsed program. In one study, 299 snakebite patients were treated with various approaches; conventional therapy resulted in >20% morbidity and 5% mortality. In the same population, treatment by electrical shock had 1% morbidity and no mortality, a substantial improvement over conventional treatment results.

A more comprehensive study of 322 patients treated with electroshock first aid showed very encouraging results. The group who were treated promptly recovered with substantially better mortality and morbidity than would be expected without electroshock first aid.

Treatment within 20 minutes of bite (282 patients) Pain subsided in 15-30 minutes Swelling regressed in 48 hours No necrosis, secondary infections, or abscesses, or other complications



Treatment 30-180 minutes after bite (40 patients) Pain subsided in 15-30 minutes Swelling increased slowly in first 24 hours, regressed in 72 hours No evidence of bleeding, necrosis, secondary infections, abscesses



Similar results have been reported by medical teams in Mexico, Guatemala, Columbia, Venezuela, Ecuador, Brazil, India, Thailand, Liberia, Kenya, Nigeria, Indonesia, and Irian Jaya. These results demand a careful evaluation of the techniques and mechanisms of electroshock; they are expected to lead to a greater understanding of a broad range of applications in natural and man made toxins. Studies in the US are anticipated under Investigational Device Exemptions but have not yet begun.

The rest of this research can be found following this LINK

Electric Shock Guidelines & Protocols

Whenever using shock, the following IMPORTANT guidelines should be followed.

Using shock on venomous bites is a FIRST AID measure.

It must be ONLY High Voltage pulsed Direct Current (DC) 15KV to 75KV at around 1mA as found in: Small internal combustion engine ignition systems. Stun Guns up to 75KV (over 75KV is more distressing on the patient and not necessary). Cattle prods have been know to work. Car ignition systems have been known to work. (Common sense should be used, some can pack quite a punch. Remove the primary coil wire to keep the engine from starting). Electric fence chargers (DC variety) have also been known to work.

It should be administered within the first 20 minutes of the bite and should not be used if the process could reduce the transportation time to a medical facility. Success has been observed with applications up to 3 hours after the bite was received.

Shock should NOT be applied to head bites or those near the heart.

Most documented cases used the spark generated by pulling the crank of a small engine (with the spark plug lead removed from the spark plug to keep the engine from starting).

Apply 1 second shocks directly to each bite incision, with a rest between applications. 8 applications have been shown to be sufficient, more do not seem to be a problem.



Overview Of Snake Bites

As indicated above, venomous bites present a danger to humans as well as animals. The results can be as severe as death or loss of a limb from highly toxic venoms, or relatively moderate such as acute swelling and discoloration, with substantial pain and fever, or relatively slight, such as minor discoloration with minimal pain and relatively localized swelling.

Typically, venom is injected into the body by a bite, which typically is characterized by a single localized area, usually on the extremities such as a limb. This is particularly true in the case of snake bites. However, with other kinds of insects, such as bees, the bites could be on the head, face and the remainder of the body, as well. Also in the case of bees, multiple bites, such as from a swarm of bees, are common. Other toxic substances in addition to animal/insect venom may be produced in the body by a bacterial infection of one kind or another, such as what typically happens in a boil, or even may be the result of humanly induced or created substances such as bacterial, biological or chemical agents introduced into the body by injection, breathing or the like, such as might occur in chemical, biological or bacterial warfare. The word toxins is used herein to cover all such substances, including particularly venom from snake bites and the like.

Chemical Composition and Effects

In the case of venomous snake bites but also with other toxins, the effect of the venom usually depends upon the amount of the venom injected as well as the toxicity and complexity of the venom itself. In some cases, such as for certain snake bites, the chemical composition of the venom is very complex with some venoms comprising up to ten or even more different toxic substances. Such toxic substances will include a large number, i.e. as many as 26, different enzymes, many of which are found in all venoms. Typically, the complex chemical compounds in such venoms act in some manner on the membranes of the body, disturbing their function as well as their organization, resulting in the range of symptoms discussed above. In many cases only a small amount of venom can produce a very significant result. Fortunately, in many cases, the time of contact between the victim and the snake/insect is minimal, so that the amount of injected venom is relatively small and the resulting effect is not nearly as great as would be the case with a large dose.

Other Kinds Of Bites

With certain other kinds of bites, such as bees, ants and the like, the venom is much less complex and not as toxic. However, it is well recognized that a fairly large percentage of the population has developed a substantial sensitivity to such venoms, and thus, severe reactions may in fact occur in an individual person, even for a venom which on an objective scale may not be particularly toxic.

Design guidelines for Shock Generating mechanisms

Probe And Grounding Plate

FIGS. 1 and 2 illustrate generally the method of treatment. It should be understood that although the following description is directed toward venomous bites, the treatment could be used for other toxins as well. Assuming that the venomous bite occurs on a limb, as represented by the numeral 10, an electrical signal is applied to the site 12 of the bite by means of the combination of a probe 14, which is generally applied in the vicinity of the site 12, and a grounding plate 16 which is typically positioned on the rear side of the limb 10 opposite from the probe 14. The probe could be pointed to maximize current density or relatively blunt or rounded to cover a larger area. Also two probes, positioned near the site of toxin or across the affected area or limb could be used in some cases, as opposed to the combination of a probe and grounding plate. The probe 14 and the grounding plate 16 are connected to an electrical signal apparatus 18.

Electrical Signal Generating Apparatus

The electrical signal apparatus 18 is designed to produce an electrical current having selected characteristics. In the embodiment shown, the signal is in the form of a pulsating DC, wherein the respective pulses decay from their peak value over a selected time interval.

Output Signal Voltage And Current Characteristics

The output signal has a relatively high peak voltage, approximately 20 kilovolts to 50 kilovolts (open circuit), but a relatively small current, on the order of 5 milliamps or even lower. The voltage must be sufficient to overcome the skin resistance of the bite victim, so that an electrical current path is completed. However, once the electrical current has been established through the body, the voltage will drop to a relatively nominal value, on the order of 5-10 volts. Low currents are used to prevent the undesirable side effects of burning or necrosis of the skin tissues. The probe could be sharp enough to penetrate the skin, which would bring the source of electric current closer to the affected tissues.

Output Signal Pulse Characteristics

The output signal is a pulsating DC, in which the individual pulses decay over a selected period of time. The pulse width in this embodiment is approximately 4 milliseconds. The duty cycle is approximately five percent although this could be varied substantially.

Methods Of Generating Electrical Pulses

Small Motor Ignition Systems

The required electrical signal can be produced by a variety of known circuits. For instance, the electrical signals produced by conventional lawnmower or outboard motor ignition systems, which generally produce an oscillating output voltage of between 4,000-20,000 volts, could be used. With the spark plug removed, the lead from the ignition circuit is applied to the bite victim and the starter pulled. Typically the victim receives a several pulses before their limb jerks away. This may be done 3 or 4 times, at intervals of several seconds. The mechanics of this design have been reproduced using a flywheel, gears, a crank and a magnito as seen in the picture to the right.

Modified Stun Gun

Also, the new 'STAR Spring Zapper' (below) is the latest design that uses a magneto, flywheel and magnets to create a spark. This design is small, can be operated by a single person, uses no batteries, and can withstand rural third world environments. More information and pictures can be found at http://www.FirstAidVenomShock.com

Also, an apparatus known generically as a stun gun, which is commercially available, has been successfully used. The stun gun circuit typically includes an oscillator/low voltage transformer circuit which provides a high voltage signal which is then rectified and stored in a capacitor. The stored charge is then dumped into a high voltage transformer, which produces an open circuit voltage of 50 kilovolts. The electrical output is thus in the form of successive signal "bursts", controlled by the trigger of the gun. The significant advantage of the stun gun is that it operates off a conventional 9 volt battery, and is readily portable. The gun can be readily modified to include the ground plate, as shown in FIG. 2. The drawbacks are that the current provided by stun guns generally greatly exceeds the required 5-10 milliamps and is very painful.

Summary

Hence, it should be understood that various circuits can be used to provide the required electrical current, although there is a significant advantage to an apparatus which is portable. It should be understood also that the characteristics of the electrical signal can be varied, although as indicated above, the voltage must be sufficient to establish the current through the body. Typically in a given treatment, the circuit is activated four or five times, so that there is a pattern of discharge and signal decay several times for a particular treatment.

Although the embodiment illustrated includes a point probe in combination with an opposed grounding plate, it is possible as mentioned above to use opposed points, and in certain cases just one probe which contains two electrodes.

It has been found that use of the point/plate embodiment is substantially uniformly successful if applied within a relatively short time, i.e. less than 20 minutes, following the bite. In such a case, there is relief of pain from the snakebite, without any long term toxic effects and no tissue damage.

As indicated above, the treatment is also effective in treatment of bacterial toxins, such as found in boils, although several days are usually necessary for complete recovery. The treatment also can be used to treat other toxins, including man-made, which are present in a patient.

Although it is believed that the electrical current has an effect on the venom itself, physiological effects on the bite victim may also play an important part. For instance, the electric current may restrict circulation in the affected area, or it may alter the molecular structure of the toxin, rendering it harmless and/or evoke a physiological reaction or response in the body which interrupts the normal action of the toxin.

Hence, an apparatus and method has been described for the prompt, effective treatment of venomous bites. The technique is effective on both humans and animals. The treatment basically involves the application of an electric current into the body portion affected, i.e. typically the site of the bite.

The Challenge

The goal of this site is to join the community of 'Venom Shock' believers, disseminate information and to work together to design a simple, economic and manufacturable device which could be used in Third World countries for first aid on venomous bites.

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We are dedicated to exploring the FIRST AID benefits of electric shock on venomous bites. If you would like to join and contribute to our site, go to Wikidot and create a account. Then come back to this page and go to the How to join this site? link.

Appendix A - Unplublished Materials

The material contained in this paper is unpublished and is used here with written permission of Doctor Ron Guderian, from his work in Esmereldas province of Ecuador. The material contained in this paper is proprietary and must not be copied or distributed to others without permission of Dr. Ron Guderian.

Introduction

Venoms from snakes, scorpions, other animals and insects have traditionally been of great concern to all who must operate in infested areas. Recent data on the use of electroshock as a first aid for snake and insect bite has extended the body of clinical data to hundreds of patients. This is an appropriate time to investigate the utility of electroshock in treatment of naturally occurring and man-made toxins.

Work has already been done with leading researchers worldwide in treatment of snakebite and related injuries using an electrical current. Up to date data on results from these studies sponsored by the National Institutes of Health, Hospital Vozandes, and other organizations are reviewed in this paper.

The most striking results have been obtained by researchers at Hospital Vozandes in Ecuador where electrical treatment of snakebite is a government-endorsed program. In one study, 299 snakebite patients were treated with various approaches; conventional therapy resulted in >20% morbidity and 5% mortality. In the same population, treatment by electrical shock had 1% morbidity and no mortality, a substantial improvement over conventional treatment results.

A more comprehensive study of 322 patients treated with electroshock first aid showed very encouraging results. The group who were treated promptly recovered with substantially better mortality and morbidity than would be expected without electroshock first aid.

Treatment within 20 minutes of bite (282 patients) Pain subsided in 15-30 minutes Swelling regressed in 48 hours No necrosis, secondary infections, or abscesses, or other complications



Treatment 30-180 minutes after bite (40 patients) Pain subsided in 15-30 minutes Swelling increased slowly in first 24 hours, regressed in 72 hours No evidence of bleeding, necrosis, secondary infections, abscesses



Similar results have been reported by medical teams in Mexico, Guatemala, Columbia, Venezuela, Ecuador, Brazil, India, Thailand, Liberia, Kenya, Nigeria, Indonesia, and Irian Jaya. These results demand a careful evaluation of the techniques and mechanisms of electroshock; they are expected to lead to a greater understanding of a broad range of applications in natural and man made toxins. Studies in the US are anticipated under Investigational Device Exemptions but have not yet begun.

Background

Venomous stings and bites are a serious medical problem whose consequences range from pain to loss of limb or life. Annually 30,000 to 40,000 deaths are attributed to snakebite worldwide. In the U.S. of a study of 460 deaths due to venomous animals between 1950 and 1959 attributed 50% to insects[27].

The most widely accepted treatment for snakebite is the immediate transport of the patient to medical facilities for treatment which may include anti-venin, tetanus prophylaxis, and broad spectrum antibiotics. Anti-venin may not be indicated as a portion of snakebites occur without envenomation[28]. Anti-venin therapy is not without its limitations. Anti-venin may induce allergic reaction or serum sickness; it has a limited shelf life, often requiring refrigeration. Anti-venins are species-specific, requiring identification of the snake species, and are not available for all species. Sources ofanti-venin are generally centralized precluding its use in many remote areas.

Anti-venin therapy is inappropriate for use in the field or as a first aid treatment. Three first aid treatment methods are suggested by the medical community for treatment of snakebite[29]. (1) incisions over the bite site and sucking out of the venom; (2) the use of a tourniquet (3) immobilization of the bite victim and use of an elastic bandage on the affected limb. Recent studies indicate that the immobilization treatment may cause fewer complications and benefit the patient[30]. It is safe to say that most other methods are controversial.

A potential alternative treatment for envenomation using high voltage electroshock was described in Lancet[31] in 1986 by Guderian et al, Well over 300 recorded cases have been treated to date. Treatment has been administered at times ranging from minutes to hours post-bite. There has been no loss of limb, pain is relieved, necrosis around the wound is arrested immediately, and the usual sequelae of untreated bite (swelling, serosanguinous bullae, bleeding, shock, and renal failure) do not occur. Only one fatality, a 2 year-old girl, was experienced. With conventional therapy, 15 deaths would have been expected out of 300 similar cases. None of the humans treated has shown adverse reaction to the electroshock administered as part of the snakebite treatment.

In vitro testing of electroshock

A number of investigators have examined the effect of electrical current on snake venom. Some of the results show decreases in venom component activity, however more work must be done to gain a better understanding of mechanisms.

Through in vitro work[29] reduced activity of the enzyme phosphatase and coagulase after treatment with electroshock has been observed. SDS-PAGE protein electrophoresis does not show any alterations of the protein profile of the crude venom following application of the electrical current. However, upon purification of the phosphoesterases from the crude venom, the "inactivation" of the enzyme by electrical current disappears.

The loss of enzymatic activity is illustrated in the figure below

In vitro tests[29] of coagulation time effects of electrical current also show a strong effect. This is illustrated in the figure below.

Escobar[33] reported the effects of high voltage electroshock on proteases, PME, PDE, and blood coagulation peptides in Bothrops venom. She found that electroshock treatment could inhibit or completely neutralize the snake venom peptides that cause blood coagulation. Electroshock treatments were most effective at higher pulse repetition rates, higher voltages, and when the venom had been diluted. Electroshock completely neutralized the coagulation effects when 20 kV at 20 Hz were applied to a 1:3000 dilution of Bothrops venom for 90 seconds. Electroshock also inhibited general protease activities in Bothrops venoms as measured by the action of venom proteases on gelatin. In other enzyme studies, electroshock reduced PME activity 40% in Bothrops asper but had little effect on PME activity of a related species, Bothrops xantogrammus, where the PME activity of the venom was already quite low. On the other hand, electroshock treatment greatly reduced the PDE activity of both Bothrops species.

Animal model studies

Animal studies have been pursued in an attempt to explain the clinical phenomena being observed. Attempts to replicate the human response to envenomation in experimental animals have not been successful. In all small animals studied — rats, mice, rabbits, cats, dogs, piglets, small sheep and small goats, NO LOCALIZED REACTION (similar to the affects on a human) to the venom could be produced. Once a reaction to the venom could be induced, it was systemic and fatal[29]. This problem, a lack of control, makes animal studies of electroshock first aid impractical.

Researchers, in fact, have reported that electroshock treatment of mice and rats following injection of snake venom does not reduce animal mortality. Johnson[33] et al. used a 12 V car battery and coil to shock mice (20 -25 kV, < 1mA average Current) within 60 seconds after injecting reconstituted rattle snake venom into the shank. The electrodes were placed on the tail and below the injection site. In another study by Howe[35] et al., rats were injected subcutaneously with reconstituted Bothrops atrox venom and shocked with one central point electrode and a surface ring electrode with a 15 mm radius, 5 minutes after envenomation. No significant differences in morbidity or mortality were found between the shocked and untreated rats.

It is not known why mice and rats did not appear to respond as humans to envenomation in these experiments. There may be significant differences between humans and these animals in their sensitivity to different venom components as they are the natural prey for snakes or they may be unequally affected by electroshock. Although it seems unlikely, the electroshock may beneficially effect the human but not elicit the same physiological responses in these animals.

Clinical Experience with Electroshock Treatment of Snakebites.

Data from one clinical use study in Ecuador includes 74 victims of poisonous snakebites who were treated with electroshock. None received anti-venin. All patients recovered fully with minor morbidity in one case. Comparison data from a group of 225 bite victims (129 received anti-venin) had 10 mortalities and there was significant morbidity. In addition a striking relationship was found in the case of treatment with electroshock, between the promptness of treatment and the resolution of pain and swelling , providing additional evidence for the effectiveness of shock treatment of snakebite. The data are used here by permission and were collected by R. Guderian, in the Esmereldas province of Ecuador. For a patient's data to have been included in the study, three criteria needed to be met:

Visible puncture wounds from the snake fangs

Clinical evidence of envenomation such as swelling or discoloration

Positive identification of all snakes highly poisonous

72 of the snakes were Bothrops species, and 1 was Lachesis muta. Most of the snakebites occurred on the toes, foot or ankle (53) , but they also occurred on the fingers or hand (13) and arm (2). Fifty-three of the victims were male, twenty-one were female. The ages of the victims ranged from 5 to 65 years with an average of 31.2 ±15.3 years. Both native Indian (15) and afro-indian (Moreno 58) races are represented, and one Caucasian.

The victims received high voltage electroshock treatment from a Kettering ignition system or from a stun gun. With the stun gun a lead to a flat metal plate is attached to one electrode of the stun gun. The flat plate is applied to the side of the limb opposite the wound site and the other electrode is applied directly to the wound. Repeated shocks of short duration (less than 2 seconds) are made. The number of shocks given varied, 44 received 4 shocks, 18 received 5 shocks, 11 received 6 shocks, and one received 10 shocks. The shock does cause involuntary muscular spasm and makes it difficult to be absolutely uniform in the delivered dose for each shock with the existing devices, hence one might give an extra shock if one had been poorly executed. Patient tolerance or fear of the consequences is also a variable.

None of the electroshock patients was treated with anti-venin. Sixty-seven received electroshock treatment within 1 hour of the bite, three received treatment within 1 to 1 1/2 hours and the remainder were treated 3, 3.5. or 8 hours after being bitten. Table 1 shows the time lapse between the bite and electroshock therapy and time before the swelling, pain and other symptoms disappeared.

Table 1 Relationship between the promptness of electric shock treatment and time to disappearance of snakebite symptoms.

The data in Table 1 show a clear correlation between the time of treatment and time required for resolution of all symptoms. On average the patients were asymptomatic within 37 ±12 hours when treatment occurred within 15 minutes of the bite. Those treated 31 to 60 minutes after the bite recovered within 45 ±16 hours. Victims treated later required correspondingly longer recovery times, e.g., those treated more than 91 minutes after the bite (an average of 248 minutes) recovered within 108 ±24 hours. This is summarized in the figure below and provides strong evidence for efficacy of the electroshock treatment.

The stringent requirements for inclusion of patient data should have precluded cases of "dry bites" in which envenomation did not occur. Nevertheless there is a small possibility that a few dry bite cases were included (e.g. the patient treated at 61 - 90 minutes whose symptoms disappeared within 24 hours). Eliminating from consideration data from patients who recovered within 24 hours would eliminate possible dry bite cases. After doing so, the remaining data (i.e. from those whose symptoms resolved after 48 hours or longer) also show a very strong correlation between time to treatment and time to resolution of symptoms.Similar results have been reported by medical teams in Mexico, Guatemala, Columbia, Venezuela, Ecuador, Brazil, India, Thailand, Liberia, Kenya, Nigeria, Indonesia, and Irian Jaya[ 36 ].

For comparison, K. Kerrigan, working at Hospital Vozandes Oriente, Shell, Pastaza, Ecuador has published data[37] on snakebite cases admitted to their hospital during the period 1980 - 1987. None of these patients received the electroshock treatment. Results from electroshock and conventional therapy are summarized in the table below.

Table 2 Data from patients treated with electroshock, anti-venin, or neither method shows a substantial difference for electroshock treatment.

Most of Dr. Kerrigan's data is from patients who were brought into the hospital, while Dr. Guderian's cases were treated in the field. Thus the elapsed times between envenomation and first treatment differ for the groups. Also presumably Dr. Guderian would be presented with cases in the field which may not have been serious enough to have been transported any distance to a hospital. Taking only the cases from Dr. Kerrigan's data in which the patients were presented within 3 hours of envenomation should be somewhat comparable. In Dr. Kerrigan's data there were 54 cases presenting within 3 hours of envenomation, 11 were treated without the use of anti-venin and 43 were treated with anti-venin. In the cases receiving anti-venin there was significant morbidity in five cases including receiving transfusions, amputations, with abscess, GI bleeding.

Published studies also show morbidity and mortality for snakebites in the region is significant, even for those treated with anti-venin. In an epidemiological study Larrick[38] et al. state that snakebite deaths account for 4% of the deaths over six generations. They also cite an incidence of snakebite (1.5 / lifetime), suggesting a mortality rate of at least 2%. The World Health Organization[38] (WHO) reports a snakebite mortality rate of 4% in 2,182 cases treated in Guayaquil, Ecuador. Even with immune-serum treatment, the WHO reported a mortality rate of 1% in a study of 5,676 Bothrops snake bites[39].

While a strong indication of unshocked results, this data cannot be taken strictly as control. There is however a striking difference between morbid sequelae for these patients receiving conventional treatment and for the patients receiving the electroshock treatment.

The effectiveness of electroshock treatment of snakebites is clearly shown by the clinical data. In addition there is a good correlation between the promptness of treatment and speed of recovery. None of the patients who were treated with electroshock received anti-venin.

A later study [29] consolidated data over a 10-year period for rural areas of Ecuador. Most of the bites in this study were on the hands of males in their 20's who were working in the fields. In 282 victims, the electrical shock treatment was applied within 20 minutes of the bite. All cases had pain localized at the site of the bite and in 4 cases there was localized swelling around the fang marks. After treatment pain subsided within 15-30 minutes and no localized swelling developed following treatment. In the 4 cases with swelling, it disappeared within 48 hours. Patients were followed by a medical officer at a health center or by a mobile medical team for up to 72 hours. No necrosis, secondary infections, or abcesses were noted at the site of the bite.

Electroshock treatment within 20 minutes of bite (282 patients)

All had localized pain

4% had localized swelling

Pain subsided 15-30 minutes of electroshock

Swelling regressed in 48 hours

No necrosis, secondary infections, or abcesses

40 patients received electroshock 30 - 180 minutes after being bitten. All had intense local pain and swelling. Pain subsided within 30 minutes of treatment. Swelling increased slowly for 24 hours; within 48 hours, there was regression of swelling and no pain. All patients were dismissed after 84 hours of observation without additional medication. No infection or necrosis were noted at the bite site.

Electroshock treatment 30-180 minutes after bite (40 patients)

All had intense pain and localized swelling

1% had plasma oozing from bite

Pain subsided in 15-30 minutes of electroshock

Swelling increased slowly in first 24 hours, regressed in 72 hours

No evidence of bleeding, necrosis, secondary infections, abscesses

Dismissed 84 hours after bite, no medication

Significant clinical observations are that for these patients, electroshock completely eliminated patient pain, secondary bacterial infections and formation of abcesses, and swelling.

Electroshock applied more than 3 hours after the snake bite did not affect patients. The author of this study did not recommend electroshock as a first aid with treatment delays of 3 hours or more.

Hypothesis of Mechanisms

Mechanisms are still being investigated. One hypothesis is that inactivation of the venom by high current density (and consequently high electric fields) takes place at the bite site. This may be caused by modification of the tertriary structural configuration of enzymes which destroys their biological activity[29] or depolarization of toxins and hence loss of their activity[32].

Appendix B - A Discussion of Snake Bite Treatments

The electroshock treatment is among the newer methods reported at achieving reasonable success in bite treatment. This is not yet considered traditional even though the earliest reports of application date quite some time back. These were not United States based field experiences and were thus less likely to end up as being counted as having moved through the time tested process of being considered traditional first aid. Still, the potentials for successful first aid reported in this area have been quite impressive. The book may continue to be open on this matter, but the approach itself, like the others, may present a contribution to an overall process that seeks out the best results. In this approach, the direct application of electric current to the bite locale is the central focus. Various presentations deliver this shock in different manners. The theory seems to rest in the basis of a very high voltage thrust at a very low amperage. Now, it is evident that whenever the application of electricity to live tissue is involved, there are some strong considerations to keep in mind. Just how much voltage is high enough? What is low amperage? Where and how often is this applied? These are serious questions and all need to be played out to establish some base line formulas for treatment. Research is still underway seeking to outline these parameters. Some people foolishly assume that since electricity is so widely utilized in the medical field for a very wide range of treatment and testing purposes, it surely cannot be that complicated to apply the principles to snake bite first aid. Anytime that high voltage, poor field conditions, a dose of frantic panic, severe pain, and the like are a part of the situation, great care should be placed upon decision making to use this technique. Yet, as a method of first aid it has much to offer and cannot be discounted due to the downside characteristics. The same principles applied to the other methods must be applied here as well.

Generally, it is accepted that DC current is more suitable for the method. This means stay away from electric plug in receptacles in a wall somewhere! The proper current can be obtained from older coil based gasoline engine ignition systems. Things such as outboard motors, lawn mowers, car or jeep engines, and the like have been pressed into service. There are currently small modified versions of the stun gun which are touted as being effective portable units sufficient to deliver the necessary shock. The idea is to hit the area with enough voltage to damage the cellular molecules of the venom. This must be accomplished at the same time that low enough amps are used to prevent tissue burning, organ damage, convulsions, and a host of other possibilities being experienced from uncontrolled voltage. This is definitely a precision approach with seeing to it that proper safeguards are being maintained. Past successes have reported that voltage in the 100K level with current at the 1 or 2 milliamper level seems to be workable. The bite area is tapped quickly in one second bursts of six or seven spots in a circular fashion around the wound. Earlier taps are closer in an effort to logically reach venom before it spreads farther out. As time in minutes progresses and swelling or other symptoms move outward, the electric taps move outward also. It has been reported that beginning immediately with the bite itself in time, a series of taps every 10 to 15 minutes for the first hour may work to reduce the impact of the venom. It should be obvious that having ready access to such a shock source is a central feature of this approach. To expend hours seeking out or building a power source is not practical. The idea in all treatments is to respond to the presence of the poison very rapidly! The sooner some can be removed, or in the case of this latter treatment, be damaged in some way, the less likely the onset or the lower the peak of some of the more negative symptoms. It is widely held that the shock properly accomplished has the direct effect of changing the shape of the venom cell such that the adhering quality to whole blood cells is reduced, thereby rendering at least a portion of the venom less able to produce the designed results. As a first aid tool, this approach also must be coupled with safe transport to competent medical service. Additionally, antiseptic procedures should be applied throughout as practical. The history of this approach is more limited but it certainly makes up for late ground by holding the most dramatic claims for rapid success in treatment with minimal resulting damage levels. This method requires a deeper investigative effort and such a continuing study is supported with great hope by those who have experienced the pain of a bite with all of the negatives associated with other treatment courses.

Appendix C - Is It Safe

A paper was written by Theodore Bernstein, Ph.D. Professor of Electrical and Computer Engineering University of Wisconsin-Madison January 22, 1985 called EVALUATION OF THE ELECTRIC SHOCK HAZARD FOR THE NOVA XR 5000 STUN GUN. It's purpose was to compare the output of the Nova stun gun with FDA safety regulations and to prove that it met the regulations and that it was safe.

You can see the contents of the report below or follow this link on the NOVA site.

Nova Stun Gun Safety Report

EVALUATION OF THE ELECTRIC SHOCK HAZARD FOR THE NOVA XR 5000 STUN GUN

Theodore Bernstein, Ph.D. Professor of Electrical and Computer Engineering University of Wisconsin-Madison January 22, 1985

SafelyDoc

INTRODUCTION

The design of most electrical equipment ensures that an individual should rarely contact energized parts and be subjected to electric shock. For such equipment electrical safety is provided primarily by insulation or guarding to prevent contact and by suitable grounding. Any contact with energized parts is considered hazardous. There are other equipment where, even though it may not be intended, contact with energized parts is expected so that the electrical safety must be provided by ensuring that any possible electric shock will not be hazardous or lethal. Examples of such electrical devices are the electric fence, medical electrical nerve stimulators, welder, cattle prod, and fly electrocuter. The Nova XR 5000 stun gun is an example of a new device where individuals are deliberately subjected to electrical shock.

The XR 5000 is a small, hand-held device powered by a 9V battery. There are two small probes extending from the front approximately 5 millimeters, 2 inches apart. The probes are intended to be pressed into an attacker's body so that an electrical shock can be delivered to incapacitate the attacker. It is important that the attacker not be injured, as this is one of the major advantages of the device.

This report evaluates the safety of the shock delivered by the XR 5000. This is done by analyzing the output current waveform and comparinq this shock to known safe and hazardous shocks. Safety criteria for the electric fence are used to compare the shock delivered to that delivered by the XR 5000.

ABSTRACT

The electric shock hazard for the XR 5000 is determined by comparing the shock delivered to the known effects of a 60 Hz shock. With 60 Hz shocks a current of 1 mA is at the threshold of perception, 5 mA is at the let-go current level where shocks are painful but not dangerous, and 50 mA is the level where ventricular fibrillation and death can occur. The XR 5000 output is a train of damped, sinusoidal pulses with an approximate 10 u s time constant. The true r.m.s. value of the output is not a valid indication of the hazard because the output contains frequency components well above the 1 kHz frequency above which the effect for a given frequency component is reduced. When these factors are considered, the output for the XR 5000 is in the 3 to 4 mA range of an equivalent 60 Hz shock and is not dangerous. The fact that the shock is delivered between two probes 2 inches apart adds to the safety because the current is concentrated in the region of the body between the two probes and only a negligible current can reach the heart. ----------------

SINUSOIDAL, 60 Hz SHOCKS

Electrical shocks involving alternating current have been investigated since before 1890 (Bernstein, 1975). Most of the recent studies have involved sinusoidal, 50 or 60 Hz currents, though the effects of other frequencies and waveforms have also been studied. This report compares the shock delivered by the XR 5000 to an equivalent 60 Hz shock. In order to do this, the effects of 60 Hz shocks are reviewed.

Threshold of Perception

For 60 Hz shocks, the lowest level of current that can be a problem is the threshold of perception level. This level, where some people may feel a slight tingle but should have no extreme startle reaction, Is usually con sidered to be 0.5 mA r.m.s. for 60 Hz currents and is the maximum allowa ble leakage current for appliances (ANSI, 1973). Dalziel and Mansfield (1950) have determined that the median threshold of perception current at 60 Hz was 1.067 mA for 28 men and 1.18 mA for four women. Shocks near but above the threshold of perception current may be a hazard because of injury caused by the startle reaction producing a dangerous body motion.

Ventricular Fibrillation

At the other extreme is the level of current where the heart may be thrown into ventricular fibrillation and death occurs. For shocks between any two limbs, Biegelmeier and Lee (1980) have re-evaluated experimental data on ventricular fibrillation induced by electrical shock in animals and related the results to the physiological response to electrical shocks. For short duration shocks shorter than a cardiac cycle, the electrical current to cause fibrillation must be large and occur during the vulnerable period, T wave. Shocks longer than a cardiac cycle can cause premature ventricular contractions that lower the shock threshold current to a minimum after four or five premature ventricular contractions. Using these concepts, a safe current limit has been established as 500 mA for shocks less than 0.2 seconds in duration and 50 mA for shocks longer than 2 seconds. For shocks between 0.2 and 2 seconds, the safe current is given by the expression

I = 100/T mA r.m.s. (1)

where T is in seconds and 0.2 s < T < 2 s.

Let-Go Current

The let-go current level of shock is not immediately lethal as is the ventricular fibrillation level. At this level of shock, with a current path through the arm, the individual cannot let go of an energized conductor. This level is hazardous in that a person is receiving a very painful shock from electrical equipment that he cannot release. Such a long duration shock may eventually become hazardous because of evoked heart arrhythmias or a decrease in contact resistance because of perspiration or burns allows greater currents. Dalziel and Massoglia (1956) have determined that the 60 Hz let—go current level where 0.5% of the individuals cannot let-go is 9 mA for men and 6 mA for women. The median let-go level is 16 mA for men and 10.5 mA for women. The let-go level where 99.5% of the individuals cannot let-go is 23 mA for men and 15 mA for women. Underwriters Laboratories (1972) requires that the ground fault circuit interrupter trip with long duration shocks greater than 6 mA as most people can let-go at currents less than 6 mA. The electric fence controller (Underwriters Laboratories 1980) is designed so that any single controller failure will not produce a continuous current greater than 5 mA because of the let-go problem. Currents above an individual's let-go current level could be hazardous and painful because the individual would be frozen to the circuit.

EFFECT OF FREQUENCY

The frequency of the electrical current is important in determining the effect on the human body of a given magnitude of current. When testing appliances or medical devices for leakage current, test loads have been devised which are supposed to simulate the response of the human body to the various frequency components in the leakage current. In order to do this, an electronic voltmeter is connected across the simulated load in such a fashion that a given reading of the voltmeter at any frequency is equivalent to the same effect shock. Underwriters Laboratories (1976) specifies a test load to measure leakage current such that the allowable leakage current is the same for all frequencies to 1 kHz. The allowable leakage current is increased directly proportional to the frequency for frequencies higher than 1 kHz up to 100 kHz. Above 100 kHz the allowable leakage current is the same as at 100 kHz——100 times the value at 1 kHz.The equivalent dc shock current for the same effect is taken as 40% larger than the 60 Hz current. The ANSI/AAMI (1978) test load is similar.

There is a question as to whether the effect on the human body of a shock from a non-sinusoidal, periodic waveform can be considered the same as the effect of each individual frequency component effect summed appropriately. Until further data are available, there is no other way to analyze a non-sinusoidal, periodic waveform.

THE ELECTRIC FENCE TRAIN OF PULSE SHOCKS

The electric fence controller (Underwriters Laboratories, 1980) provides a basis for determining what is considered a safe electric shock for a train of pulses. The electric fence has been used for many years with the realization that humans will contact the fence but must not be injured. The controller delivers a pulse type output with the output during the "on time" being of the peak discharge-type output or of the 60 Hz sinusoidal-type output. All tests for the controller are performed with a 500 ohm load.

The "off period" for the controller must be greater than 0.9 s for a sinusoidal type output or greater than 0.75 s for a peak discharge-type output. This "off period" is essential to allow an individual to get off the fence as the output during the "on period" is greater than the let-go current level. Continuous output is not permitted. Any single failure in the controller must not produce a continuous current greater than 5 mA.

The "on period" for peak discharge-type controllers must be less than 0.2 seconds. For this peak discharge-type controller, the output delivered to a 500 ohm load during the "on time" is limited to a given value of milliampere-seconds, charge, depending on the length of the "on period." The curve for the "on period" for peak discharge-type controllers provides allowable milliampere-second values for the time period from 0.03 s to 0.1 s. For "on periods" from 0.1 to 0.2 seconds the allowable output is 4 mA-s. The allowable output is reduced to 2 mA-s for a 0.03 second "on period."

For sinusoidal-type output the "on period" must be less than 0.2 s. For "on periods" between 0.025 s and 0.2 s, the allowable current must be less than

1 = 75 — 350T mA r.m.s.

where T is the "on period" in seconds. For "on period" between 0.025 s and 0.2 s, equation (2) allows sinusoidal type r.m.s. currents between 65 and 5 mA. These values are well below the 500 mA level considered dangerous for a single shock of such duration. It is important to note, however, that the fence controller produces a train of pulses rather than a single pulse.

Noting that the pulse repetition frequency for the sinusoidal-type pulse is approximately 1 Hz, the true r.m.s. current can be calculated for different pulse "on periods" when the r.m.s. value of the current during the pulse is given by equation (2). The results for pulse width between 0.025 s and 0.2 s are given in Table 1

TABLE 1 True r.m.s. Current Related to Pulse Width

Pulse Width (T) True r.m.s. Current (s) (mA) 0.025 10.47 0.05 12.84 0.07 13.34 (max) 0.10 12.62 0.15 8.65 0.2 1.9

This indicates that the highest output current is about 13 mA which is above the 60 Hz let-go current for some individuals. The current should not electrocute a person at this level. There still is a question as to whether the true r.m.s. current given in Table 1 can be equated to the effect of 60 Hz currents. The pulse train will have frequency components above 1 kHz.

To study the frequency components for the pulse train the Fourier spectrum (Cooper, 1967) for a single pulse is calculated. Because the pulses are periodic with a frequency of 1 Hz, the amplitudes for the individual harmonics are proportional to the value of the Fourier spectrum at discrete frequencies starting at 1 Hz and at all higher frequencies separated by 1 Hz. The peak discrete frequency component is 2/t times the Fourier spectrum value at that frequency where T is the period for the pulses in seconds. Above 1 kHz the effect of the frequency components on the human body decrease inversely proportional to the frequency. Using the Fourier spectrum and the decrease in effect of the shock for frequencies above 1 kHz, the effective r.m.s. current for the n'th harmonic is given in equation (3)

I n = (75-350T) T ( [sin(n-60 π T / (n-60) π T] + [ sin(n+60) π T / (n+60) π T] ) x {1+(n/105)2}(1/2) / {1+(n/103)2}(1/2) mA r.m.s.

where n is the harmonic and, in this case, its frequency (n = 1,2,3,—-); T is the "on period" in seconds; and the frequency of the sinusoidal output during the pulse is 60 Hz. Above 1 kHz, equation (3) indicates that the harmonics are small and falling off rapidly so that the frequency components below 1 kHz are the most prominent. Thus, the true r.m.s. current values in Table 1 are equivalent to the 60 Hz values as far as effect on the human body is concerned.

NOVA XR 5000 SHOCKS

The Nova XR 5000 has an output consisting of a train of damped sinusoidal pulses. The current output depends on the electrical resistance between the probes. This will vary depending on the type of contact and whether the shock is delivered through clothes.

In comparing current levels between the output of the XR 5000 and the previously discussed physiological effects it is important to take into account the path of the current. Ventricular fibrillation is caused by current traversing the heart. The XR 5000 has a very well defined path between the two closely spaced probes. The current delivered to the heart will be negligible. This makes discussing lethality using the total current a technique that provides an extra margin of safety. Medical inspection of volunteers undergoing XR 5000 shocks revealed no clinically significant changes to their E.K.G.

The action of the XR 5000 in causing muscle contraction shows an action much like the let-go phenomenon. In the arm currents of 5 to 10 mA cause this effect.

The XR 5000 is battery operated and ungrounded. Any electrical current will only travel between the two probes. A user holding the device and contacting ground with his other hand will receive no shock, as he is not in the current path between the probes.

Output Voltage Waveform and Parameters

The output voltage waveform for the XR 5000 consists of a train of damped sinusoidal pulses where each pulse is of the form

v(t) = Vo (e )(-t/T) sin ωd t V

the pulse repetition frequency is 16 Hz. From oscilloscope traces of the output voltage for various resistance loads, the parameters in equation (4) can be evaluated. The time constant T, and the frequency, ωdcan be measured directly from the trace. V0 is calculated by finding the time, for the first voltage peak and the magnitude of the first voltage peak,Vp from the trace and then using

Vp =Vo e(-tp/T) sin ωd tp V

to find Vo

Using the output voltage traces for loads of 200, '160, and 1020 ohms the parameters shown in Table 2 were determined.

TABLE 2 XR 5000 Output Parameters Load resistance (ohms)

200 460 1020 1700 Vp (V) 1500 4000 8000 13,000 tp (µs) ← 2.5 → 2 T (µs) ← 10 → 8 Vo (V) 2000 5000 10,000 17,600 ω(d) (rad/s) ← 7 * 105 → 6.28 x 105 fd (kHz) ← 111.4 → 100 Effective Output Current

Using the values from Table 2, the r.m.s. output current for a pulse train of damped sinusoids with a repetition frequency of 16 Hz can be calcu lated and are shown in Table 3.

TABLE 3 Calculated Effective Currents

Load Resistance (ohms) r.m.s. (mA) 200 62.6 460 68.0 1020 61.4 1700 57.4

The effective current shown in Table 3 could be hazardous if they were at 60 Hz; however, the output pulses contain high frequency components which are much less lethal than 60 Hz currents. It is necessary to consider all the frequency components for the pulses using a suitable weighting factor.

Frequency Components in XR 5000 Output

The XR 5000 output is a train of damped sinusoidal pulses of the form

v(t)=Voe-at sin ω dtV

The Fourier series frequency components for the train of damped sinusoidal pulses are obtained from the Fourier spectrum (Cooper, 1967) for the single damped sinusoidal pulse of equation (6) and is:

F(jw) = Vo ω d/{(jw)2 + 2a(j ω + (a2 + ω d2)}

where a = 1/T = 105s-1th Equation (7) can be recognized as a second order system with the following parameters

Undamped natural frequency ( ωn) = ( a2 + ωd2 )1/2 = 7.07 x 105 rad/s or

Undamped natural frequency fn = 112.5 kHz

and Damping ratio ζ = a/ ωn - 0.14

Since the bandwidth for such a system is approximately 172 kHz, the spectrum has significant high frequency components within the bandwidth, but these are above the 1 kHz frequency so the effects of electric shock on the human body for a given magnitude current are reduced.

Because the damped sinusoidal pulses are periodic with a frequency of 16 Hz, the r.m.s. values for the Fourier series harmonics are proportional to the value of the Fourier spectrum at the harmonic frequency. For this case the Fourier series has its fundamental frequency of 16 Hz with the higher harmonics all the multiples of 16 Hz.

Using equation (7), the r.m.s. value for the harmonic at each discrete harmonic frequency, ω is

I(j ω ) = [ √ 2f / r] [ Vo ωd / a2+ ωd2 ] [ 1/ {1-[ ω2/( a2 + ωd2)]} + j{ 2a ω / (a2 + ωd2)} ] A r.m.s.

where f =16Hz a ; a = 1/T = 105s-1

wd = 7 X 105 rad/s

and w has discrete values at w = 2π (16n) where n = 1,2,3,

The true r.m.s. value for the current including the first n harmonics is the square root of the sum of the squares for the first n harmonic values from equation (8).

The harmonics from equation (8) must be reduced by introducing the frequency response for the human body when the effects for shock currents are reduced proportional to frequency for frequencies between 1 kHz and 100 kHz. This can be accomplished by multiplying the magnitude for a given harmonic, n, found in equation (8) by the factor:

G(jw) = [ 1 + ( f/105)2]1/2 / [1 + (f/103)2]1/2

(1 + 2.56 * 10-8n2)1/2 / (1 m + 2.56 * 10-4n2)1/2

Combining equations (8) and (9) the r.m.s. values for the current to the

600th harmonic, 9600 Hz, have been calculated and are show in Table 4 Including higher harmonics would not increase the value significantly because of the attenuation at the higher frequencies.

TABLE 4 Effective XR 5000 Output for Frequency Components

to 600th Harmonic, 9600 Hz

Load Resistance (ohms) I (mA)

r.m.s.

200 3.03 460 3.29 1020 2.97 1700 3.43

PRIOR STUDIES RELATING TO XR-5OOO TYPE SHOCKS

In a report prepared for the U.S. Consumer Product Safety Commission (Bernstein, 1976), another device intended to be used on people and to deliver a train of damped sinusoidal pulses at a frequency of 13 Hz was evaluated. This report indicates that the output was equivalent to an approximate 9 mA, 60 Hz shock. A later study where the effects of the different frequency components were more accurately calculated showed that the device output was equivalent to an approximate 3 mA, 60 Hz shock (BernsteIn, 1983). These techniques were used in this report.

The XR5000 is certainly as safe as the device evaluated for the U.S. Consumer Product Safety Commission. In fact, it is safer because the well defined current path between the closely spaced probes of the XR5000 will significantly reduce the current delivered to the heart.

CONCLUSIONS

1. Table 4 shows that the output for the XR 5000 is about equivalent to a 3 mA, 60 Hz shock. Such a shock is not dangerous.

2. The 3 mA shock is at about the let-go current level. The shock may be more intense than that caused by such a 3 mA let-go current in the arm because the current density at the probes is greater and because of the sensation caused by the spark from the electrode to the skin.

3. Because the shocking current is only in the path between the electrodes about 2 inches apart, the current that might reach the heart is much less than in a limb-to-limb or an across-the-chest shock. This adds to the safety.

4. The units can be used in a damp or wet environment without hazard to the user. The unit may not work well because leakage between electrodes, but the operator should not be shocked if he keeps his hand in its usual position.

REFERENCES

ANSI ClOl .1 (1973). American National Standard for Leakage Current for Appliances. American National Standards Institute, New York.

ANSI/AAMI SCL 12/78(1978). American National Standard Safe Current Limits for Electromedical Apparatus. Association for the Advancement of Medical Instrumentation, Arlington, VA.

Bernstein, T. (1975). Theories of the causes of death from electricity in the late nineteenth century. Medical Instrumentation, 9, 267-273.

Bernstein, T. (1976) Letter report to Mr. Neil P. Zylich, U.S. Coonsumer Product Safety Commission. February 12, 1976. Revised February 7, 1977.

Bernstein, T. (1983). Safety criteria for intended or expected non-lethal electrical shocks. Symposium on Electrical Shock Safety Criteria sponsored by The Electric Power Research Institute, The Canadian Electrical Association, and Ontario Hydro. Toronto, Canada. September, 1983.

Biegelmeier, G. and W. R. Lee (1980). New Considerations on the Threshold of Ventricular Fibrillation for a.c. shocks at 50—60 Hz. Proc. lnstn Elec. Engrs., 127, 103—110.

Cooper, G. R. and C. D. McGiIIem (1967). Methods of Signal and System Analysis. Holt, Rinehart and Winston, New or , pg. 121.

Daiziel, C. F. and T. H. Mansfield (1950). Effect of Frequency on Perception Currents. Trans. Am. Inst. Elect. Engrs., 69, part 2, 1162-1168.

Dalziel, C. F. and F. P. Massoglia (1956). Let—go Currents and Voltages. Trans. Am. Inst. Elect. Engrs., 75, part 2, 49—56.

Underwriters Laboratories (1972). UL 943, Standard for Safety, Ground—Fault Circuit Interrupter, pg. 16B, revised January 7, 1977.

Underwriters Laboratories (1976). UL 544, Standard for Safety, Medical and Dental Equipment, 2nd ed., pg. 30, revised January 17, 1977.

Underwriters Laboratories (1980). UL 69, Standard for Safety, Electric Fence Controllers, 5th ed., pp. 12-13.