"The medical advice that will support a conservator's decision to forego life-sustaining treatment must include the prognosis that there is no reasonable possibility of return to cognitive and sapient life. 'When dealing with patients for whom the possibility of full recovery is virtually nonexistent, and who are incapable of expressing their desires,' this prognosis is '"the focal point of decision." However, such a prognosis does not compel the conservator to forego life sustaining treatment. Instead, based on the medical advice, . . . section 2355 still requires the conservator to make a good faith decision whether treatment is necessary. Case law has not made clear whether "sapient" has any meaning distinct from "cognitive." In Matter of Quinlan, supra, 70 N.J. 10 [355 A.2d 647], the New Jersey Supreme Court quoted expert witness Dr. Fred Plum (who has been credited with coining the PVS term), who in his testimony distinguished between sapience and a vegetative state: "We have an internal vegetative regulation which controls body temperature, which controls breathing, which controls to a considerable degree blood pressure, which controls to some degree heart rate, which controls chewing, swallowing and which controls sleeping and waking. We have a more highly developed brain which is uniquely human which controls our relation to the outside world, our capacity to talk, to see, to feel, to sing, to think. Brain death necessarily must mean the death of both of these functions of the brain, vegetative and the sapient. Therefore, the presence of any function which is regulated or governed or controlled by the deeper parts of the brain which in laymen's terms might be considered purely vegetative would mean that the brain is not biologically dead." ( Id. 70 N.J. at p. 24 [355 A.2d at pp. 654-655].) "The concept of good faith precludes a decision affected by a material conflict of interest. Good faith also requires the conservator to consider the available information relevant to the conservatee's best interests. . . . Life-sustaining treatment is not 'necessary' under . . . section 2355 if it offers no reasonable possibility of returning the conservatee to cognitive life and if it is not otherwise in the conservatee's best interests, as determined by the conservator in good faith." ( Drabick, supra, 200 Cal. App. 3d at pp. 216-218, fns. omitted.)