Does execution by lethal injection involve conscious asphyxiation?

April 23, 2007

Execution by lethal injection may cause death by asphyxiation, and prisoners being executed may be conscious and may experience pain, claim the authors of a new study published this week in PLoS Medicine. Leonidas Koniaris and colleagues from the University of Miami assessed data from two US states that release information on executions together with previously published work on the drugs used in the protocols for lethal injections. They conclude that these protocols may not reliably effect death through the mechanisms intended.

Lethal injection is used for execution in a number of countries, most notably the US and China. The current regimens for lethal injection in the US are based on one drawn up by legislators in Oklahoma, which in turn to appear to have been based on personal opinion rather than independent research. The drugs used are a barbiturate, thiopental (which acts as an anesthetic, but does not have any analgesic effect), a neuromuscular blocker, pancuronium bromide (which causes muscle paralysis); and an electrolyte, potassium chloride (which stops the heart from beating). Each of these drugs on its own was apparently intended by those who derived the protocols to be sufficient to cause death; the combination was intended to produce anesthesia then death due to respiratory and cardiac arrest. Following a number of executions in the US, however, it has recently become apparent that the regimen as currently administered does not work as intended. Some p risoners take many minutes to die, and others become very distressed.

The authors concluded that in the current regimen thiopental might not be fatal and might even be insufficient to induce surgical anesthesia for the duration of the execution, and that the doses of potassium chloride used did not reliably induce cardiac arrest. Hence, potentially aware inmates are likely to die through asphyxiation induced by the muscle paralysis caused by pancuronium. The authors conclude that even if lethal injection is administered without technical error, those executed may suffocate, and therefore ''the conventional view of lethal injection as an invariably peaceful and painless death is questionable.''

In a related editorial the PLoS Medicine editors discuss the study's findings and their reason for publishing it in the journal. They state that "It is not our intention to encourage further research to "improve" lethal injection protocols. As editors of a medical journal, we must ensure that research is ethical, and there is no ethical way to establish the humaneness of procedures for killing people who do not wish to die," and note that "the data presented by Koniaris and colleagues adds to the evidence that lethal injection is simply the latest in a long line of execution methods that have been found to be inhumane." They argue that the evidence presented in this paper "will further strengthen the constitutional case for the abandonment of execution in the US."
Citation: Zimmers TA, Sheldon JP, Lubarsky DA, López-Muñoz F, Waterman L, et al. (2007) Lethal injection for execution: Chemical asphyxiation? PLoS Med 4(4): e156.



Related image for press use:

- Caption: Lethal injection table - provided by California Department of Corrections and Rehabilitation


Dr. Leonidas G. Koniaris
University of Miami
Surgery, Cell Biology, Anatomy
3550 SCCC
1475 NW 12th Ave
Miami, FL 33156
United States of America
+1 305 243-1684
+1 305 243-7083 (fax)

Related PLoS Medicine Editorial:

Citation: The PLoS Medicine Editors (2007) Lethal injection is not humane. PLoS Med 4(4): e171.



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