Should a patient be unable to make his or her own decisions -- for example, because of a coma -- a health care proxy becomes the legal decision-maker on his or her behalf. The proxy's decisions are not supposed to be predicated on his or her own beliefs. Rather they're a reflection of the expressed wishes of the person he or she is representing.
To that end, a health care proxy may have to devote considerable time to his or her duties. To put it bluntly: Dying can take a long time, or an apparently terminal condition can be subject to sudden reversals. A health care proxy should be prepared to be in and out of a hospital for days or weeks at a time. He or she will have to speak with doctors, receive updates about the patient's condition, consider avenues of treatment, ask doctors and specialists about the patient's illness and what options exist and, perhaps most importantly, make decisions about whether to agree to certain procedures.
All of this means that being a health care proxy is a grave responsibility. It can also be an emotionally difficult one, particularly if the proxy must deal with family members who don't share the opinions laid out in the advance directive. A health care proxy will have to be resolute, inquisitive, organized and capable of making tough decisions. Above all, he or she will have to put the patient's established wishes at the forefront of all decision making.