After a broad-based, in-depth study of real-world applications, an independent research team says its findings “suggest” that department policies restricting the firing of Taser probes to the chest because of heart safety concerns “are unnecessary.”
Case analysts led by Dr. William Bozeman of the Wake Forest University School of Medicine in North Carolina determined that conducted electrical weapon (CEW) discharges impacting on the front torso are no more dangerous than those delivered to other parts of a suspect’s body.
In some 1,200 instances of Taser use taken from police files, they found no evidence of cardiac complications resulting from CEW contact, even in “worst case” scenarios where Taser probes delivered an electrical charge that would have passed directly over the heart.
The Bozeman study contrasts sharply with a much smaller report that has sparked buzz in the media and law enforcement circles. The source of that report is Dr. Douglas Zipes, a heart specialist who has testified as a plaintiff’s expert witness in multiple lawsuits against Taser’s manufacturer.
Analyzing eight cases in which subjects lapsed into unconsciousness and some died after Tasering with the X26, Zipes suggests that a CEW’s electrical shocks can lead to death from cardiac arrest. His claim is set forth in an article in Circulation, a cardiology journal published by the American Heart Assn.
Zipes’s critics argue that his approach was biased, his research methods were unscientific, and his conclusions are suspect.
Whatever the limitations, one authority on in-custody death, Dr. John Peters Jr., predicts that Zipes’s contrarian report, published in a respected professional journal, will still have “significant tactical and economic implications for law enforcement.”
In exploring this controversy, let’s look first at the latest evidence from Bozeman, an associate professor of emergency medicine and a highly respected researcher who has been investigating CEW outcomes since 2004.
The pig problem & human safety
Some experiments on anesthetized pigs have shown that in rare instances the electrical discharge from a CEW near the heart can disrupt normal functioning of that organ with fatal results. To date, Bozeman writes, this “has not been replicated in human studies, even with ‘worst case’ precordial [immediately in front of the heart] placement of CEW probes in human volunteers.”
Among these human tests were ones conducted by Bozeman-led researchers in which police officer volunteers were Tased and “the immediate cardiac and cardiovascular effects” were evaluated. The team found “no adverse cardiac effects or rhythm changes” and concluded that Taser exposure “overall was safe and well-tolerated.”
Still, there are occasional unexplained in-custody deaths that occur after Taser use and, as Bozeman has observed, test subjects who are healthy, compliant police officers may not experience the same outcomes as suspects Tasered in the wild, so to speak, where sustained struggling, heightened excitation, drug and/or alcohol intoxication, and unknown pre-existing physical and mental debilities may well be the norm.
The goal of Bozeman’s latest study, then, was to assess Taser heart risk in actual confrontations with criminal suspects. The project was funded by the National Institute of Justice.
Bozeman’s team of physicians examined a vast database of use-of-force reports from a cooperating “research network” of law enforcement agencies scattered across six geographic areas in the U.S.
They found 1,201 cases of Taser application. Of these, the researchers determined, only three sustained “moderate to severe” injury related to the Tasering, mostly from falling. Two post-Tasering deaths were discovered but were not related to the effects of a CEW, according to medical examiner investigations.
From the gross pool, Bozeman’s team winnowed out all drive-stun incidents (that mode is not a potential heart threat, according to existing animal and human studies) and all single-probe-only contacts. From those that remained, the team identified 178 cases (22%) in which Taser probes had landed on the suspect’s chest within a radius where the electrical discharge potentially could have affected the heart. (CEW contacts in other parts of the body are not considered a heart risk.)
Overwhelmingly subjects in the field who were studied were male (94%) and relatively young (mean age 32; range 13-80 years). In each case, researchers reviewed all available documentation, including detailed police reports and medical records.
• No deaths occurred in any of the 178 subjects actually Tasered in the heart zone.
• There was no evidence in any of these subjects of any cardiac dysrhythmia; that is, any impairment, disruption, or complication of normal heart performance.
• There was no higher rate of injury of any kind among subjects shocked in the chest versus other target areas.
Their conclusion, quoting from a report of the study in the Journal of Emergency Medicine:
“These findings based on actual field data confirm that fatal cardiac dysrhythmias are unlikely to occur when CEWs are deployed on human subjects in real-life situations…and suggest that policies restricting anterior thoracic [front torso] discharges of CEWs based on cardiac safety concerns are unnecessary.”
An abstract of the Journal report is available free by clicking here.
Bozeman says, “This study adds to the accumulated medical evidence that Tasers are safe and effective and that their risks overall are extremely low. Tasers have been associated with lower rates of injuries to suspects and officers than other traditional intermediate-force options such as physical force, pepper spray, and handheld impact weapons.”
On the other hand…
In his Circulation article, Dr. Zipes says, in effect, Not so fast….
A cum laude graduate of Harvard Medical School, Zipes is past president of the North American Society of Pacing and Electrophysiology/Heart Rhythm Society and a “distinguished professor emeritus” at the Indiana University School of Medicine in Indianapolis. He has written over 700 articles and 17 books, according to his online biography.
As a physician specializing in the study of electrical activity in the human body, he also is a persistent testifier in Taser-related lawsuits, having appeared at least eight times as an expert witness on behalf of plaintiffs who claim the device is dangerous. He acknowledges his expert-witness work in his paper and the cases he describes come from his court appearances.
An abstract of his article, “Sudden Cardiac Arrest and Death Following Application of Shocks from a TASER Electronic Control Device,” can be accessed free by clicking here.
In this paper, Zipes describes eight instances in which males ranging in age from 16 to 48 received shocks from the Taser X26, with “1 or both barbs in the anterior [frontal] chest near or over the heart,” and lost consciousness “during or immediately after the [electrical] shock.” One, after defibrillator intervention and the injection of heart stabilizing drugs, survived. The others all died.
The subjects received shocks lasting from 3 to nearly 50 seconds. One received 13 shocks totaling 62 seconds in less than three 3 minutes. Four had BAC levels ranging from 0.111 to 0.35 (in the U.S., 0.08 is the legal limit). Two of these subjects plus two others were “alleged to have structural heart disease,” Zipes says.
Studying these cases “as part of litigation,” Zipes writes that he discovered “evidence detailing the mechanism by which [a CEW] can produce transthoracic stimulation resulting in cardiac electrical capture and ventricular arrhythmias leading to cardiac arrest.” In laymen’s terms, Zipes says that electrical impulses radiating from Taser probes in the chest affect the heart, causing abnormal heartbeat, leading to stoppage and death.
Zipes specifically mentions ventricular fibrillation (VF), a fatal rhythm where the heart does not generate blood flow, so blood pressure drops significantly and severely impacts the flow to vital organs, and ventricular tachycardia (VT), an excessively rapid heart rate which, untreated, can deteriorate into fatal ventricular fibrillation, a common cause of sudden death.
After analyzing information “where available” from police and EMS reports, Taser dataports, defibrillators, electrocardiogram (ECG) strips, and autopsy results, Zipes writes that he has concluded that “cardiac arrest caused by VF can result from [a Taser] shock.” Indeed, he says officers should “suspect this adverse response in any victim who loses consciousness” after a CEW shock. He warns to “avoid chest shocks if possible.”
An editorial accompanying Zipes’s article in Circulation observes that his work “demonstrates a direct association between delivery of [a CEW] shock and the onset of cardiac arrest” in at least some humans in whom “other possible causes are not present.” Zipe’s “most salient” point, the editorial says, is that “the energy delivered by [the Taser] is sufficient to achieve [heart disruption] when delivered to the anterior chest.”
Michael Brave, an attorney for Taser International, charges that Zipes’s “case series” is replete with “deceptions, half-truths, and analytical gaps,” many of which are “not obvious to anyone who does not intimately know and understand all of the scientific and medical literature” on CEW outcomes. “To adequately explain all the problems would take about 200 pages.”
Taser’s VP of communications, Steve Tuttle, characterized Zipe’s paper as “clearly self-serving” of his “primary interest” as a plaintiff’s expert witness. “One example of Dr. Zipe’s bias is his omission of important facts that contradict his agenda.” In one of his cases, for example, “video clearly showed that the officer missed the subject” when firing the X26, Tuttle alleges. “Scanning electron microscopy of the probes also confirmed that no current was delivered through the wires to the subject. There are key facts that contradict the role of the Taser device in all of [Zipes's] cited cases.”
Force Science News sought comment on all this from a well-known researcher who has published reports of her own on ECWs and on sudden in-custody deaths. Dr. Christine Hall is a practicing emergency medicine specialist and is affiliated with two universities in Canada. She also serves on the faculty for the Force Science Analysis certification course and was recently appointed to a committee of 13 impartial experts who will report next year to the Canadian Police Research Center on the “medical and physiological impacts” of CEWs.
Zipe’s analysis, she says bluntly, “is not a study” in the scientific sense of the word (“a group of anecdotes is not a study”) and it is “not proof of anything.” Among “noteworthy scientists” of her acquaintance who have read Zipes’s article, including heart specialists, “none find it to be scientific evidence of medical certainty,” she says, adding: “I am continually flabbergasted at how fast people who are convinced Tasers are bad will embrace something like this and ignore more solid work.”
She ticks off a laundry list of Zipes’s article shortcomings, in her view: poor methodology in selecting the cases examined and the inclusion of some that are not relevant, inadequate data about the subjects and Tasering events involved, failure to specify precisely where Taser probes impacted or whether electrical current was actually delivered to the chest in the cases described, questionable selection and interpretation of ECG strips, a lack of fellow authors to participate in and critique the findings, an unrelieved suspicion of bias and conflict of interest–to mention a few.
“He has established that there are some cases that may be worrisome,” she says, “but salient features that would help in assessing his report are missing. Expert opinion is not evidence.”
She points out that if the situation were reversed and a researcher presented eight cases with equally skimpy and missing information to prove that Tasers were safe, “critics would be very quick to discard the series as ‘proof.’ Scrupulous methodology and scientific rigor are important on both sides of this discussion.
“Dr. Zipes raises an important hypothesis that invites research that holds to scientific standards. Dr. Bozeman has explored that hypothesis with proper methodology and concluded that the risk Zipes suggests appears to be extremely low.”
No “quick-fix” resolution
Still, the likely reality is that Zipes’s paper will serve to prolong the debate about Taser safety, in the opinion of some observers.
John Peters Jr., a PhD who heads the Institute for the Prevention of In-Custody Deaths, points out that Zipes’s is “the first peer-reviewed article that concluded an X26 probe deployment to the chest area can cause cardiac arrest leading to sudden death.” This conclusion, he told Force Science News, “seriously challenges the theory of 100% safety” regarding the Taser and comes from a source with impressive professional credentials.
While praising Taser as a street tool, Peters also reminds that the manufacturer’s own product warnings caution that CEWs “have not been scientifically tested on at-risk ‘susceptible populations,’ ” such as “frail, elderly, pregnant, small children, and individuals with low body mass indexes.”
All this combined assures, Peters says, that “there will not be a quick fix” to the controversy over CEWs and arrest-related or in-custody deaths. Zipes’s work, he predicts, “will have a ripple effect through the [CEW] industry and carry over into the legal arena for sure.”
Nov. 12-14 Peters’s Institute will hold its annual conference in Las Vegas. Zipes will speak on his findings and a panel of medical and legal experts will discuss Taser issues, Peters says. Dr. Hall is also scheduled as a speaker. For more conference information, click here.
NOTE: To aid future researchers, Hall urges law enforcement agencies to be diligent in “specifically documenting where Taser probes and drive stuns land (including one-probe-only contacts and total misses), which darts are paired, and the nature of the deployment event overall for every CEW use. This information is profoundly important, whether the subject lives or dies.”
She explains, “If we cannot determine the precise location of probes and the outcomes from them, we can never establish with certainty the risk in real-world circumstances.”
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