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The 19605 saw both the advent of open-heart surgery and the increasing use of cardiaccatheterization procedures. More and more patients with externalized transarterialcatheters, usually enclosing leads that could be quickly connected to an external cardiacpacemaker, were appearing in the new cardiac care or special are units of hospitals. Oncephysicians realized that this highly conductive pathway not only bypassed the usuallyprotective layers of relatively resistive body tissues, but that it also directed current to themost electrically sensitive areas of the inner walls of the heart, concerns arose about thepossibility that these patients could be electrocuted by currents much smaller than thosethat would affect the exterior of the body.

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The Great Debate on Electrical Safety-In Retrospect 281

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The Great Debate onElectrical Safety-InRetrospect

Malcolm G. RidgwaySr, Vice President, Technology Management and ChiefTechnology Officer, MasterPlan Inc,Chatsworth, CA

large currents passing through low resistance grounding conductors, could easily sendhigh magnitude currents into the exposed conductive pathways,

The concept of equipotential grounding, in which substantial (green) grounding con-ductors are used to connect all exposed conductive surfaces to a central grounding pointin a star configuration, was developed as a prime defensive measure against this new haz-ard. Others championed the use of isolation transformers as the best way to reduce leak-age current in the ground circuits of the hospital's electrical distribution system, Severalregulatory and standards-serting organizations began taking notice.

In April 1968, the division of medical sciences of the National Research Council(NRC) held a two-day workshop on "Electrical Hazards in Hospitals" that was attendedby more than tOO people. The proceedings of this workshop were edited by Dr. CarlWalters and later published by the influential National Academy of Sciences (Walter,1970). Carl Walter was a renowned surgeon at the Peter Bent Brigham Hospital in Boston,a member of the faculty at Harvard Medical School, and chairman of the committee onhospitals of the National Fire Protection Association (NFPA). Dr. Walter has been cred-ited with establishing one of the world's ftrst blood banks in a basement room at Harvardin 1934, and later ( 1949) with the invention of the blood bag, which ended the cumber-some and dangerous procedure of pumping blood directly from donor to patient via paraf-fin coated glass tubes. In addition, his insight and pioneering work with the Castlecompany led to the introduction of high pressure steam sterilizers (sometimes called

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282 Clinical Engineering Handbook

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autoclaves) for reprocessing surgical instruments. Before the autoclave, surgical instru-ments were simply "sterilized" in boiling water.

At the 1968 NRC-sponsored workshop, Dr. Walter first speculated on the probableincidence of death by "microshock" in US hospitals. During a discussion of nationalstatistics on electrocution that were available at the time, he claimed that an insurance

actuary, whose statistical hobby is electric shock and electrocautery injuries, had assuredhim that there were 1200 misdiagnosed electrocutions annually in hospitals during 1964and 1965. That would have amounted to one "misadventure" annually in every sevenhospitals in this country. Walter said these misadventures were classified as cardiac

arrest, but the deaths occurred during resuscitation efforts unrelated to the patient's pri-mary disease or during application of electric appliances. He also said the statistics were

culled to demonstrate the prevalence of the problem and to show why the medical pro-fession has not recognized the problem (i.e., during a lifesaving venture, those involvedmay not perceive what is going on). Walter claimed to have encountered three suchinstances in a recovery room himself and further said that when the situation was recre-

ated, it was readily apparent exactly which device caused the trouble. Finally, Walterwent on to assert there were at least a dozen analyses in existing literature of the patientelectrocution risk and claimed that is why so many doctors were becoming interested inelectric shock.

On January 27, 1969, a report titled, "Accidental Electrocutions Claim 1200 Patients aYear" was published in Electronic News (Electronic News, 1969). The report quotedmicroshock statistics obtained from Dr. Walter during a telephone interview. These samestatistics were repeated again during presentations made by Dr. Walter and others at the71" Annual Meeting of the American Hospital Association in Chicago in August 1969.After the proceedings of the NRC workshop were published in 1970, these statistics wererepeated at a press conference and widely reported throughdut the national press.

In June 1970, a report was distributed by the UPI wire service that Ralph Nader, anattorney and consumer activist, had alleged in a speech that 5000 deaths attributable tomicroshock occurred each year in the nation's hospitals. To this day Mr. Nader has notprovided any independent substantiation for his figure.

In March 1971 the Ladies Home Journal ran an article quoting Ralph Nader titled,"Ralph Nader's Most Shocking Expose,'" which stated that, "at the very least, 1200Americans are electrocuted annually during routine diagnostic and therapeutic proce-dures," and that "medical engineers such as Professor Hans von der Mosel, co-chairmanof the Subcommittee on Electrical Safety of the Association for the Advancement ofMedical Instrumentation and safety consultant to New York City's Health ServicesAdministration, believe that the number might be ten times as high as the conservativeestimate of 1200" (Nader, 1971). This is the source of the sometimes quoted "estimate"of 12,000 deaths per year. Interestingly, this same article states that, "Only three hospitalsin the country have biomedical engineers on their staffs to supervise the operation andmaintenance of complex machines: Downstate Medical Center in New York City; SinaiHospital in Baltimore; and Charles S. Wilson Hospital in Johnson City, N. Y."

By the mid-1970s, the NFPA's Committee on Hospitals had developed and distributedfor public comment some proposed amendments to Article 517 of the 1971 edition of the

National Electric Code (NEC) that would require all hospitals to have isolation trans-former-based "Safe Patient Power Centers" in all special care areas of the nation'sapproximately 6000 hospitals. The potential financial impact of this proposal shocked thehealth care community. The technical inadequacy of the proposed solution also shockedthe embryonic clinical engineering community.

In the spring of 1971, shortly before the Annual NFPA Meeting in San Francisco atwhich the Committee on Hospitals' proposed amendment would be voted on, the Hill-Burton Program Committee convened a private meeting in Rockville, Maryland, at whichten experts, in "electronics in hospitals" were invited to debate with Dr. Walter and his

technical advisors about the merits of the proposed new requirements. In a follow-upreport, one of the ten experts concluded Dr. Walter arrived at his "estimate" of 1200

deaths per year due to microshock by noting one patient death in his hospital he suspectedas having been the result of microshock and then extrapolating that to 1200 microshockelectrocutions per year on the basis of his hospital caring for about one in 1200 of all USpatients yearly.

Participants at the meeting indicated that the proposed solution was technically inad-eqnate because the isolation monitor, that the National Electric Code required to beused with an isolation transformer, injects far more current into the circuit than the"safe" level of 15 microamps. Dr. Walter's team was unable to rebut the criticism. Thereport goes on to state that, "The Hill-Burton Program Committee'sfindings were neverpublicized, but the committee did inform the NFPA that if isolated power in all specialcare areas was required by the NFPA in its forthcoming standards, the committee would

terminate its long-standing requirement that hospitals receiving its funds comply with'NFPA's standards." This was a substantial threat-at that time virtually all new hospi-tal construction and renovations were subsidized with federal funds from the Hill-Burton Program.

When the proposed amendments to the NEC were presented at the NFPA AnnualMeeting in San Francisco in May 1971, they prompted a very lively floor debate, afterwhich adoption was deferred and they were returned to committee by a 106 to 38 vote ofthe membership of the electrical section. .

In spite of this period of spirited discussion about the reality or non-existence of thisnew, perhaps life-threatening hazard, and the uncertainty about whether or not the variousproposed countermeasures and elaborate safety tests could eliminate or reduce the threat,a battery of new electrical safety requirements appeared. Many of these requirements per-sist today in only slightly modified form as part of various regulations. The JointCommission on Accreditation of Hospitals issued new standards that prescribed quarterlydocumented electrical safety testing for all of a facility'S! patient care equipment. InCalifornia, the State Department of Health issued stringent electrical safety measures aspart of its new requirements for general acute care hospitals. Title 22 of the StateAdministrative Code introduced the soon-to-be-obsolete concept of the "electricallysensitive patient" and a host of related tests. It was a time of absurdities, such as festoons

of green grounding wires connecting every piece of exposed metal surface within the

vicinity of any special care bed (even in the adjacent bathrooms) to substantial central

grounding posts. However, diligent, dedicated investigations over the next several yearsfor possible occurrences of microshock failed to turn up any credible evidence that this

ingeniously conceived but still theoretical hazard was claiming any lives.In September 1973, Dr. Joel Nobel, Director of the Emergency Care Research Institute,

made a statement during hearings before a Senate subcommittee on the proposed MedicalDevice Amendments of 1973:

"The issue of microshock electrocution, its real versus claimed incidence, its wide-spread publicity, the enactment of codes and laws to combat it, and the economicfortunes of the electrical transformer industry, are inextricably intertwined. Phonystatistics have been used to promote the sales of safety equipment and manipulatethe National Electric Code to require the use of specific products. We are not sug-gesting that the microshock electrocution issue was fabricated by the industrial andcode making camps and consumer advocates. Each, however, capitalizing on theissue, has distorted both the technical problems and the priorities rather badly. Theresult is that many millions of dollars have been diverted from more critical areas ofhealth care. This electrical safety issue has, however, performed a useful catalyticfunction in drawing attention to other problems associated with the use of technol-ogy for health care. It has helped hospitals to understand the broader needs for engi-neering support of patient care, including the judicious purchase, inspection, andpreventive maintenance of medical equipment.

In later testimony, he added:

"Our information and priorities are sometimes distorted by special interest groups,however, and this is acceptable. By way of example, consider how much attentionhas been devoted to the problem of electrical safety in hospitals during the last 5years, especially by the engineering community and the manufacturers of safetydevices and equipment. Speculation is often translated into reality, or at least belief,by the very fact of statement or publication. Bogus statistics on electrocution in hos-pitals have been proclaimed and republished without end or confirmation, for 5years. Many millions of words have been written about microshock and many mil-lions of dollars spent to avoid it. It is obvious, however, that we still know nothingof its real incidence. Is it a widespread problem or a phantom? We are not sug-gesting that the electrical safety problem is nonexistent. Our data show that it does

exist, and it is significant; but its characteristics and magnitude are rather differentthan is generally believed. Our biggest problem is not electrocution by microshockbut, instead, inadequate or unreliable power. Not too much electricity but too little.

And in August 1975, a report appeared in the journal The Medical Staff under the head-ing, "The Myth of Iatrogenic Electrocution: Its Effect on Hospital Costs." That report dis-cussed Walter's widely publicized claim that there were 1200 electrocutions a year in UShospitals and how that charge was reported regularly thereafter in the lay press. The reportwent on to point out that evidence supporting Walter's claim had never been produced andthat John Bruner, MD, assistant professor of anesthesia, Harvard Medical School, flatlystated to an AMA annual scientific assembly in 1975 that there had been no documenteddeath due to electricity in a US hospital in more than a decade. While Bruner did admit

he was among those first concerned with iatrogenic (physician-caused) electrocution, hereported having subsequently developed little evidence to support concerns that it mightbe a common occurrence. On the contrary, Bruner said that unwarranted concerns aboutmicroshock likely lead to the scrapping of useful equipment in favor of high priced"safety-featured" gadgetry. While acknowledging the potential for injury wherever elec-tricity is used and where haste, stress, and moisture and other environmental factors com-bine to increase that risk, Bruner nonetheless saw that much of the effort and cost incurredin addressing microshock had little real benefit since the magnitude of the hazard waslargely imaginary in the first place.

In the meantime, someone had-with a stroke of genius-realized that this entirethreat could be completely eliminated by simply protecting the exposed conductive endsof the patient's catheter. Proper terminations for transarterial catheters providing lowimpedance pathways to the heart and great vessels became the order of the day, and elec-trically sensitive patient's need for special environmental consideration disappearedalmost overnight. Articles on electrical isolation of the patient appeared. See, for exam-ple, Guidelines for Clinical Engineering Programs; Part I: "Guidelines for ElectricalIsolation" (Ridgway, 1980).

A byproduct of this extended episode, however, was the discovery that the existingquality of maintenance of the typical hospital's ever-expanding inventory of electronicequipment was inadequate. A new high intensity focus on equipment maintenance andsafety was born.

Another interesting sidebar is the parallel, then subsequent, debate about the rationalefor perpetuating the isolated power requirement in operating rooms where the use of flam-mable agents had been prohibited. The original requirement for isolated power had beenintroduced into the NFPA standards governing anesthetizing locations in 1941, along withother antistatic measures intended to reduce the number of accidents due to the ignition.of flammable agents such as cyclopropane.

In 1970, the standard addressing anesthetizing locations (NFPA 56-Code for the Use ofFlammable Anesthetics) had been renumbered as NFPA56A and given the title "Standardfor the Use of Inhalation Anesthetics (Flammable and Nonflammable)." According to thisnew document, anesthetizing locations where the use of flammable agents was prohibiteddid not have to install or use any previously required antistatic safeguards, except the iso-lated power system. In retrospect this might appear strange, until one considers the otherissues faced by the NFPNs Committee on Hospitals at that time. The committee was advo-cating the use of isolated power systems (IPS) in other special care areas of the hospital asa safeguard against microshock. The, often acrimonious debate continued throughout the1970s and well into the next decade, documented in Guidelines for Clinical EngineeringPrograms; Part IV: Isolated Power in Anesthetizing Locations? History of An Appeal,(Ridgway, 1981). The IPS advocates finally settled for permitting isolated power in anes-thetizing locations, but not requiring it. The debate was particularly interesting because

advocates of the less stringent approach required considerably more professional courageand belief in their analyses than those advocating the "safer," more extravagant solution.One approach that proved useful in bringing some uncertain observers around to the more

radical position was the use of a probabilistic illustration to semi-quantify the level of risk,documented in Guidelines for Clinical Engineering Programs; Part III: The Risk ofElectric Shock In Hospitals (Ridgway, 1981).

There have been no significant adverse trends in electrical accidents in operating roomsover the past 20 years. The predominant categories of eqnipment-related misadventuresin the operating room continue to be patients accidentally burned by poorly implementedelectrosurgical procedures, and patients injured by pressure sores resulting from extendedcontact with the unyielding surface of the surgical table. Both of these problems are oftenmisdiagnosed as accidental bums.

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The Great Debate on Electrical Safety-In Retrospect 283

References

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Nonflammable), NFPA 56: ende for the Use of Flammable Anesthetics. Quincy, MA, National FireProtection Association, 1970.

Nader R. Ralph Nader's Most Shocking Expose. Ladies' Home Journal 3:98-179, 1971.

Nobel J. Testimony before a Senate sub-committee on the proposed Medical Device Amendments of1973. Washington, DC, September, 1973.

Ridgway M. Guidelines for Clinical Engineering Programs. J Clin Eng 5:287-298,1980.Ridgway M. Guidelines for Clinical Engineering Programs. J Clin Eng 6:287-298, 1981.

Walter CWo Electrical Hazards in Hospiials. National Academy of Sciences Workshop Proceedings.Washington, DC, 1970.