In our mob we are only allowed to stop if:
1 Signs of breathing and circulation resume
2 An MD declares death
Going on an 8 hour defib course this thursday, very happy that we are now allowed by law to use them.
Did CPR for real once, elderly gent who collapsed shovelling the first snow of the season at my kids' school.
Took over an hour for the ambulance to get there, and they were the longest 60 mins of my life. Especially the part after I had heard the umistakeable death rattle and knew that I had to keep at it anyway untill the med folks got there.
Breathing down the throat of a dead body not for the faint hearted.
So if you have any doubts about yourself being able to do that, leaving CPR to another crewmember is nothing to be ashamed about.