The big, really big issue, and I hate to say it. Is that, depending on the jurisdiction and laws in place, executions cannot be done by professionals. Most of the people who would know how to do it properly, medics, nurses, engineers, are ethically banned from participating or facilitating executions. Not that this stops them all from participating, and in some contexts some do, but on the general, executions on the USA are performed by completely incompetent individuals.

The more reason to just not fucking do them in the first place. How did they botched it using a mask when almost every single expert on medically assisted death recommends at least a sealed hood.