If you were in a serious accident, a good emergency room staff could have you on a ventilator, feeding tube, etc. before your family gets to the hospital. If the situation is grave, and you can’t speak for yourself, you would need someone to speak for you. The legalese for such a document includes “Advance Medical Directive,” “Living Will,” “Medical Power of Attorney,” and “Healthcare Proxy.” You want it to be clear about which of the anxious people in the hospital speak for you and what they are supposed to do.
The hospital might give you a “Medical Power of Attorney” form to fill out, but it is drafted by the hospital’s attorney, not yours. You might not be in much shape to sign it either. That is why I include such a document in every estate plan. If you are in the ICU, and don’t have one, you’re too late.