Oboler S K
Clin Geriatr Med. 1986 Aug;2(3):547-76.
Patients who suffer severe brain damage may be brain dead, even though their cardiorespiratory function is supported by mechanical ventilation. According to criteria established in the United Kingdom and the United States, if these patients meet the preconditions of apneic coma that is attributable to diagnosed irreversible cause, and the presence of drug intoxication, hypothermia, or metabolic coma is excluded, then documentation of absent brainstem reflexes and apnea despite a PaCO2 of 50 mm Hg or greater will confirm the presence of brain death. If the brain is dead, the patient is dead, regardless of the state of his circulation, and he should be declared dead and removed from the ventilator. If the patient has lost higher cortical function but brainstem function is preserved, he may be in the persistent vegetative state and live for years with apparent sleep-wake cycles but no awareness of any external or internal stimuli. As the prognosis for recovery from the persistent vegetative state is absent, there is no ethical responsibility to continue treatment other than to provide basic nursing care to maintain the dignity of the patient.
即使通过机械通气维持心肺功能，遭受严重脑损伤的患者仍可能脑死亡。根据英国和美国制定的标准，如果这些患者符合因诊断为不可逆病因导致的呼吸暂停昏迷的前提条件，且排除药物中毒、体温过低或代谢性昏迷的存在，那么尽管动脉血二氧化碳分压（PaCO2）达到或高于50毫米汞柱时仍无脑干反射和呼吸暂停的记录，将证实脑死亡的存在。如果脑已死亡，患者即已死亡，无论其循环状态如何，应宣布其死亡并停止使用呼吸机。如果患者丧失了高级皮质功能但脑干功能得以保留，他可能处于持续性植物状态，并在数年中维持明显的睡眠-觉醒周期，但对任何外部或内部刺激均无感知。由于从持续性植物状态康复的预后不佳，除了提供基本护理以维护患者尊严外，没有继续治疗的伦理责任。
