Canary, this has got to be causing a huge amount of stress and I am sorry. As I said earlier, although not very well, I completely understand why you don't want to cath your OH, and I agree with you and would feel the same way (for what that is worth).
I agree that my mother's surgery in 2017 went much better from an anesthetic standpoint than I would have expected. It helped that it was a fairly quick procedure, so only about an hour or less actually "under" the anesthetic. It helped that I was permitted into the pre-op area and spoke directly to the surgeon and the anesthesiologist about my concerns and they listened and understood.
I do think my mother had some decline, but it's hard to identify the anesthesia as the cause, as there were a number of contributing factors and I can't actually point to the anesthesia as a problem.
I'm just gently urging you to not fixate on an anesthetic as a definite problem. The bladder issue has to be dealt with one way or another and it is NOT your fault. If he has to has surgery, that is also not your fault. Please lay the blame where it belongs, on the disease. I definitely understand how it can feel that we are condemning our PWDs to this or that (I have been there) but we are not responsible for them having dementia.
It is awful and I am sorry.