File whatever your wishes are with your doctor and a local hospital. The HIPPA laws prevent any type of disclosure.
You could always fill it out, then void/rip/burn it. Anything with a date that superceeds it is what they will go by.
When I was an ER/ICU nurse, I had members of the HLC escorted by the police out of the hospital, who, by the way, had that perrmission slip.