If you suffer cardiopulmonary arrest there is no time to try to contact your durable power of attorney. You either resuscitate or you don’t. If there is no DNR you will get the full treatment. It’s not as pretty as they show on TV shows however.
Yes, it the situation you describe you are right.
Ahead of time, you can still plan for other situations, with a durable power of attorney. Mine is on file with my doctor and either of the two hospitals I’m likely to need.