A man is admitted to the hospital, unconscious, with a history of serious health

A man is admitted to the hospital, unconscious, with a history of serious health problems and a high blood alcohol level. He has no identification and no family with him. On his chest, he has a tattoo: “Do Not Resuscitate”, and a signature, his, right-justified beneath it. Do you resuscitate him or let natural events take their course?

(Serious Question. This happened recently.)