It didn't. This writer made it all up. 5 minutes from the start he was dead. Sadly I know of an industrial "accident" where a guy went into a confined space that was full of argon. That's all it took, and he never felt a thing. Just went to sleep. Such a death is too good for a murderer.
Thanks for the info. They made it sound like the guy was writhing for 22 minutes. If the 22 minutes describes the entire procedure than that is reasonable.