Yes, apparently they call covering with plastic wrap “occlusion” - it helps prevent the cream from dehydrating and gives more opportunity for it to absorb into the skin. I occlude even when I’m not supposed to (e.g. the compounding pharmacy explicitly says not to occlude their cream), and it is one of the ways people end up with enough lidocaine in their blood stream that they die from it.

There were two women in the U.S. who put lidocaine on their legs for a laser session and used plastic wrap, and they died. I, however, have survived putting plastic wrap on my legs - I just break up my sessions into two parts, upper and lower legs, so I can reduce the surface area exposed to lidocaine. I’m also larger, so maybe my body can handle larger doses, and I intentionally eat a meal which may or may not help for various reasons (just speculation on my part).

I’m sorry you don’t benefit from anaesthetic and pain meds - I’m surprised it’s both since opioids work differently than lidocaine as I understand it, but either way that is awful - are you able to get general anaesthetic, do you know? I can’t imagine needing surgery in those circumstances …