I didn't read the story in the OP until yesterday and wow, that's a good piece. Well written and thought provoking. So, anyone who hasn't read that story, should do so.

I spoke to my wife about this and she reiterated what Bike Rat and HawkOwl have said. A DNR will not stop them from intibating you or having a machine breath for you. They won't use the paddles to restart your heart, but they will hook you up to a respirator. You will need a DNI to avoid that AND, neither of these is going to come into play with the EMTs; only later, at the hospital.