The patient is not conscious during these spasms, and feels no pain.
EDIT: Nitrogen hypoxia is an instant and painless death experience, because you pass out almost without conscious awareness, the same as if you go under the gas they have at the dentist while counting down from 10 and never remember getting to 1. The difference is that the body's death is very slow, as the body's tissues are deprived of oxygen and slowly run out of gas and stall out. As long as the patient continues to not spike in CO2, they will remain unconscious and unaware through the entire process - as necessary and brutal as it is to - you know - stop a body.
EDIT2: Exercise reasonable doubt when reading the comments below which are calling into question whether the patient 'gasped for air' or doubt for some reason that a mask is adequate. 1) The patient held their breath from the nitrogen intake as long as they could. This is the same as you sitting on a dentists chair refusing to inhale the gas. You will quickly suffer the normal heightened discomfort until your brain takes executive control and just makes you to inhale. The patient in this case brought their will right up against that reflex, a miserable experience and one in which I can't imagine it was a comfortable mental space to be in. Then the inhale reflex kicked in and they nearly instantly lost consciousness. Over the next hour or so their body slowly ceased function, without tripping any of the really scary nervous system alarms. Patient never woke up. 2) A mask is preferred in systems like this because of the inherent safety risk involved for the administers with invisible, body-encompassing volumes of nitrogen. A mask is also totally up to the task, as anyone who's been put down at the dentist can attest to. These masks also have multiple, multiple added redundancy features which help protect the air seal, as well as post-review-diagnostics. They're safe. The main concern in this situation is administer training, in the proper handling of the body's seizures such that the mask isn't somehow pried off.
Except they said he was gasping for air. Nitrogen hypoxia wouldn't do that, because you'd still be exchanging CO2 and your body wouldn't recognize the lack of oxygen in the air.
I'm not doubting anything your saying, but calling someone who is being murdered by the state the patient is icky, even if the methods being used are analogous to those used on patients who are receiving medical care. It also underlines the point that, of course the victim resisted because they were being killed, compared to a dental patient who is willingly undergoing a procedure they can expect to wake up from. Nitrogen hypoxia may be an effective way of administering a humane death to a willing participant, but in some ways giving a false perception of control to the victim (as long as I can hold my breath I won't die, as obviously futile as that may be) is undermining all of the considerations of physical discomfort that go into describing the process as humane
That seems like a good idea. If they really want to execute someone, make the official of the state shoot them on video. I'm guessing capital punishment would be almost zero within 10 years, because nobody wants to be seen as a cold-blooded killer, especially when they know that people could review the video.
Nah instead two elections cycles later a candidate will be elected, who will be running ad breaks and monetizing execution videos, all while parading patriotic bullshit.
This would backfire as you'd see people voting for right wingers more because it's "Cool and manly to kill people", you'd also get the foot in the door for legalized bloodsports.
I'm guessing the actual problem is with a method allegedly killing painlessly in minutes being "tweaked" to kill with maximum prejudice in the longest possible time... Knowing humans as I know humans, I don't think the "witnesses" would be in any discomfort seeing exactly what they came to see.
I hope they investigate and publish details. Nitrogen was supposed to be painless - it's used for suicide capsules after all. So I wonder what went wrong here.
Nitrogen is way better than CO. They just fucked up the delivery system, as government usually finds a way to fuck up somehow.
The problem with injections is they have to use a mishmash of different drugs because no drug company wants to have their products associated with executions and everybody reacts differently to drugs so you can't predict how long or how violently it might result in.
Everyone reacts the same to nitrogen gas though, it's predictable and peaceful and cheap as long as you do it right. One theory I heard was that they used a mask which was a closed system so he was able to breath his own breath for a long time since you don't use all the oxygen in every breath. They should have had a system where each breath is expelled out from the mask and in from the nitrogen source, like a back flow stop valve or something.