NOVEMBER 15-30, 2007


Doctors question safety of Tasers
after deaths

After three men killed this fall, doctors
debate police Taser use

The deaths of three Canadians, all killed this fall shortly after being shot by police with stun guns, have drawn renewed attention to the safety of the "non-lethal" devices.

Claudio Castagnetta, an Italian immigrant, died in Quebec City on September 21 after being shot by police with a Taser on September 18. Robert Dziekanski, a Polish immigrant just arriving in Canada, died at the Vancouver International Airport minutes after being shot with a Taser early October 15. Quilem Registre died in a Montreal hospital on October 18 after being Tasered during a drunk-driving arrest four days earlier. The number of deaths over such a short period of time — along with 14 other Canadian deaths after Taser shocks since 2003 — has led to calls from the public for reconsideration of police's use of the stun guns, and they're looking to physicians to provide answers. But those answers have thus far been elusive.

Dr John Butt, a forensic pathologist, says understanding the reasons for the death of Mr Dziekanski, the most high-profile victim because he died in public at the airport shortly after being shot with a Taser, will be a challenge. Was it caused by the shock, or due to his reportedly "agitated" state (though no drugs or alcohol were found in a post mortem tox report), some trauma suffered when he was restrained, or a combination of these factors? "I don't think you're going to get a very good answer to that question because you can't experiment," says Dr Butt, who has looked at deaths from conducted electricity devices (CEDs) in the past. He suggests the repeated shocks from a stun gun could have played a role in the man's death. He concluded as much in 2005 when asked to review the medical literature for a BC Police Complaints Commission report on CEDs. Too many shocks could arrest respiration and should be avoided, says Butt, but more studies need to focus on the still poorly understood physiology of people suffering from a controversial condition called "excited delirium."

In 2005, a pair of Chicago physicians wrote a letter to the editors of New England Journal of Medicine claiming that CEDs can cause ventricular fibrillation (VF). They had recently treated a 14 year-old boy who had gone into VF after being shocked with a Taser stun gun. The boy was resuscitated by paramedics at the scene, but the letter attracted international interest.

Medical advisors to the weapon's manufacturer, Taser International, said the doctors' report was "speculative and not backed by scientific evidence." Dr Mark Knoll, Taser International's scientific and medical board chair, told NRM by email that the authors of the letter should have known better than to go off half-cocked. The company has blamed the boy's medical crisis on metabolic acidosis resulting from "excited delirium" — a vague, drug intoxication-related diagnosis often cited by Taser International. But the condition doesn't appear in any psychiatric literature or diagnostic guides; the American Civil Liberties Union has called excited delirium a method of "whitewashing" in-custody deaths. Taser International insists illicit drug use can cause excited delirium, which increases the risk of adverse events from the shock, including death. Indeed, all three recent cases in Canada have involved allegations of intoxication. None of those, however, have been proven.

The medical literature on stun gun-induced VF has demonstrated that it can occur, but that it's highly unlikely. "In my mind it's not an issue," says John Webster, PhD, a professor of Biomedical Engineering at the University of Wisconsin who has studied the question. Using pigs as subjects, Dr Webster measured how close to the heart the barb from a stun gun would have to be to cause VF. The result was 17mm and even less when he revised his method of inserting the barb following criticism from Taser scientists.

"We've done a lot of work trying to estimate the probability that a human could die of ventricular fibrillation," explains Dr Webster. "It's a few per million kind of thing. You've got to have a very thin person with a dart between his ribs right over his heart."

Chicago cardiologist Dr Wayne Franklin, one of the authors of the 2005 NEJM letter that is responsible for much of the current controversy, declined to comment. Though he insists it's "an extremely important issue," he says his lawyers have told him not to speak to the press.



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