There's a good article[1] on this topic that talks about how older doctors generally choose to forego lifesaving measures. I think about it a lot because it seems like when a professional who's in the best position to know the tradeoffs makes this kind of decision for themselves they probably understand the risk/reward better than you or me.

[1] https://www.saturdayeveningpost.com/2013/03/how-doctors-die/

[delayed]

Plenty of people who make the sausage don't want to eat it.

I never wanted to go into medicine. Thus I do not believe the preferences of a typical older doctor represent my preferences in this respect.

I read an article once of a nurse who kept CPR going on her husband for somewhere around 2 hours until they could get him to a hospital that was able to restart his heart. I believe he ended up okay. CPR obviously isn't invasive tubing, but it's still kind of hard on the body.

It depends on the situation.

If it's part of a long decay I would categorically refuse anything like that. If it's due to an abrupt and fixable thing give it a try.