"Coma" can mean a wide variety of things, and a persistent vegetative state still isn't considered "dead", as was the case here. Judgement of death relies on s

"Coma" can mean a wide variety of things, and a persistent vegetative state still isn't considered "dead", as was the case here. Judgement of death relies on specific tests that establish the absence of cerebral and brainstem functions. See, for example: http://n.neurology.org/content/neurology/45/5/1012.full.pdf http://n.neurology.org/content/neurology/45/5/1012.full.pdf When the brain stops functioning systems such as electrolyte balance and internal temperature control often go as well, and we don't know yet how to keep bodies without brain function functional for extended periods of time (as opposed to comas where the patient's brain can still control autonomic processes.) In cases where a patient isn't dead, they or their health care proxy have the right to turn down treatments, including those necessary for life. Not everyone wants to be kept alive in a persistent vegetative state, even if they are not dead, and for plenty of reasons other than the cost.