Wednesday, May 09, 2007

The mechanics of death by lethal injection

I recently read Better: A Surgeon's Notes on Performance (reviewed here). One of the passages that fascinated me entirely describes the process by which a lethal injection is administered.

It’s quite morbid – but an education worth the time if only it means understanding the debate around the humaneness of the capital punishment du jour. Much of the material here is from Gawande’s book and Wikipedia.


The protocol was proposed by Oklahoma State Medical Examiner Jay Chapman in 1977 and validated by Dr. Stanley Deutsch, then Chairman of Anesthesiology at the University of Oklahoma. And considering death by shooting (too unreliable), hanging (too grisly) or electrocution (not humane enough), this has emerged as the primary way of executing death row inmates in the US and increasingly, other countries as well.

It involves three drugs administered in sequence.

The first one that goes in is between 2.5 to 5 grams of Sodium Thiopental, which is about 5 to 10 times the recommended maximum for therapeutic use. This causes a loss of consciousness in about 10 seconds. Sodium Thiopental is a short lived anesthesia, spreading to the brain first, but then distributing itself across the body causing the patient to regain consciousness. But in this quantity, it causes respiratory arrest and circulatory collapse. In other words, it could kill you in approximately 15 minutes.

After about one minute, this is followed by 60 to 100 mg of Pancuronium Bromide. This is a muscle relaxant when administered in doses of 6 to 10 mg. The bigger dose essentially causes paralysis. It is also the drug debated the most by critics of death by lethal injection. Pancuronium Bromide can potentially dilute the Sodium Thiopental, causing the patient to wake up but unable to respond to pain because of the induced paralysis.

Finally 120 to 240 milli-equivalents of Potassium Choride are administered. This pushes up the resting electrical activity of the heart muscle resulting in ventricular fibrillation. Eventually this will cause an asystolic cardiac arrest.

Thirty-seven states in the US use death by lethal injection. Texas leads the pack with 379 by the end of last year.

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