All due respect and all that, but I disagree with the contemporry interpretation of Torah that recognizes the respirator as an device providing an artificial means of prolonging life only until the time that it is used, but then treats it as a "natural" element of the patient's existance that may not be removed once it has been employed.

The more logical interpretation, it seems to be, is that removal of the patient from any such device would not be considered active "killing," but rather simply "allowing" the natural course of events to ensue.

I also think it bears repeating that we do not and cannot KNOW whether an unresponsive patient is suffering pain or not. The person may indeed be in great physical and/or psychic pain, while unable to communicate their distress to anyone. The position that artificial means of prolonging respiration can be removed if the patient is visibly suffering, but not if he/she is comatose, begs a question that we truly cannot answer.