Subject: Speaking of killing things...
Some ignorant and uninformed questions (I am not a medical doctor) about the methods of execution used to implement the death penalty, prompted by yet another controversial case, this time in Alabama. Alabama used nitrogen hypoxia, which was described as being slowly suffocated, and which one witness to the execution said was the most violent of the 5 he had witnessed, the executee violenting convulsing for many minutes.

Why is this so difficult? Why not carbon monoxide exposure/poisoning which is billed as causing drowsiness and a maybe a headache, then falling asleep and never waking up? I suppose it's not always that simple?

Why not propofol injection (which seems to be the anesthesia of choice for colonoscopies and other medical procedures not requiring deeper anesthesia), followed by carbon monoxide or dioxide poisoning? Can it still result in a visibly uncomfortable death? (Of course, what the person experiencing it is actually feeling would remain a mystery even absent visible signs of distress.)

And if not propofol, why not the medical anesthesia methods used to induce the very deep unconsciousness necessary for major surgery? Followed by some method of depriving the brain of oxygen by introduction of increasing concentration of N₂/CO/CO₂ gas?

Finally, a 20mm cannon round to the head would clearly result in instantaneous death, and since the brain would be literally disintegrated, there could be no pain or even discomfort. But this method, though inarguably "comfortable" for the one being executed, might be pretty hard on the witnesses.😉

Are there really no good options here?