Actually, a so-called official jw document is no more valid or comprehensive than getting a healthcare proxy form and filling it out and having 2 people witness your signature. You can choose any health treatment you want or don't want on it. Everyone should have such a form so if you are unconscious, you will have chosen someone to represent your wishes and there won't be any questions what you want.
Terry Schiavo ring a bell.
Blondie