It's really important to address all your legal issues prior to any major surgery! Remember, a small number of people have died on the table (dunno how many, don't even try to find out). So take a few minutes to prepare for the worst -- while hoping for the best!
A helpful article:
Can Patients Make Good Decisions? - Forbes
In the above article, see the 5 listed resources, that will provide state-specific resources, like this one:
https://www.compassionandchoices.org...nce+Directives
I'll sticky this topic, it's very important for obvious reasons.