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Lethal injections may cause suffocation

Study cites flaws in mix used to execute prisoners

Angel Dias took 34 minutes to die after lethal injection. Angel Dias took 34 minutes to die after lethal injection.

MIAMI -- Some prisoners executed by lethal injection in the United States may die of suffocation while they are still conscious and in pain, University of Miami researchers said yesterday in a study that concluded the drugs do not work as intended.

The study, published in the Public Library of Science journal PLoS Medicine, raised new questions about whether the lethal cocktail violates the US Constitution's ban on cruel and unusual punishment.

Lethal injection is the primary method of execution for 37 US states and the federal government, though more than a dozen states have halted or suspended the procedure as a result of legal or ethical questions.

The mix contains an anesthetic, thiopental; pancuronium bromide, to paralyze the muscles and lungs; and potassium chloride, to stop the heart.

First adopted by Oklahoma lawmakers looking for a humane alternative to the electric chair, the combination is supposed to produce unconsciousness and then death due to respiratory and cardiac arrest.

The researchers studied drug dosages and time elapsed until death in 42 lethal injections in North Carolina and eight in California. They concluded the thiopental might have been insufficient to keep the prisoners unconscious in some cases, based on concentrations in their blood after death.

They said the potassium chloride, which causes an intense burning sensation, did not reliably hasten death, finding prisoners given it died no faster than those who got only the other two drugs.

They concluded that the pancuronium was the only reliably fatal part of the cocktail, meaning the executed may actually have died of suffocation as it paralyzed their lungs.

In cases where the injection was botched and the drugs were delivered into muscle or under the skin rather than into a vein, prisoners would be fully aware as the paralysis took hold and the potassium chloride was administered, said Teresa Zimmers, who led the study.

"It would sort of be the equivalent of slowly suffocating while being burned alive," Zimmers said in a telephone interview.

The researchers said that was likely the experience of Florida inmate Angel Diaz, who took 34 minutes to die in December after the needles were inserted improperly.

Doctors and nurses, bound by a medical code of ethics, are barred from administering lethal injections. But even when the injections were done properly, there were doubts the anesthesia was adequate to avert suffering.

It was unclear whether levels measured in the blood after death accurately reflected those before death, the authors cautioned. But they said execution witnesses have reported that some prisoners were visibly distressed even after the anesthesia was injected, and in four cases they tried to sit up.

"The reason that people support lethal injection is because they perceive it to be a humane medical procedure," said Dr. Leonidas Koniaris, associate professor of surgery and senior author on the report. "Here we provide more evidence that it is anything but that."

Since the Supreme Court upheld the death penalty in 1976, the United States has had 1,070 executions, 901 of them by lethal injection, according to the Death Penalty Information Center.

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