DNR is usually the patient's choice - I have never heard of it being imposed by staff, although there can be errors - at one stage Veronica's case file had been marked DNR due to a misunderstanding which I was able to correct - this was about 7 years ago, and a good while before she actually died. At that time, sadly, nothing could save her.
A triage decision that sorry, we can do nothing to save this person' is something different - it is never said that bluntly, I am giving a precis
Mike