I think it's important to know if a DNR or other type of directive is in place even in cases when the situation may not be dire. Things can unfortunately become unstable very quickly, so the more informed the medical staff is, the more likely they can stay true to a patient's wishes. If he does not have family handy or easy to reach, it may be that they wouldn't know if a directive exists anyway. Two weeks on a ventilator is serious of course, but not unheard of - lets hope his body is using this time to heal effectively.