You can sign it yourself or have a friend sign it, but only if you have a power of attorney. If you are a critically ill patient without family or friends, you can ask the doctor on duty in the hospital to sign for you and fill in the formalities later if you want to have an operation. By the way, if this situation is life-threatening, no matter whether you have money or not, you will go straight to the operating table with the green light. Our doctors are not so heartless, unlike those TV or bad doctors.