Ages ago the gp asked me about OHs end of life. Did I want DNR? Yes I did, one for me too, even though I'm only in my 60s. Nothing was put in writing, however, until recently when he went into another care home for respite. I was more than happy with this. Then came the unexpected, a guy with advanced dementia who had never had a UTI suddenly had an infection ( somewhere). Did I want antibiotics administered?
It's a question, out of the blue, that floors you. Well, yes. That type of infection can be knocked on the head fairly easily - usually. If it turns to pneumonia, then what? Probably no, but there's no guarantee that's what I will say.
You need to think about these things at all stages of life, so when they come you've a vague ideas of your tipping point. It's a bit like deciding when someone has to go into care.
I dislike having to make these decisions about someone else, but who else would/should do it?