• Andrew Baker and Sam D Shemie.
• Departments of Critical Care and Anesthesia, Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, Ontario, Canada; Departments of Anesthesia and Surgery, Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Ontario, Canada. Electronic address: bakera@smh.ca.
• J Crit Care. 2014 Aug 1;29(4):687-9.

AbstractThe capacity for consciousness and self-awareness is uniquely synonymous with human life and personhood, and its absence is necessary and sufficient to identify that death has occurred. The presence of these functions is uniquely synonymous with human life. Ongoing organ function, response to infection, growth, wound healing, or the ability to sustain an unborn fetus do not alone constitute the unique experience of life and personhood. Death occurs after the loss of the ability to use oxygen by the brain, which occurs because of either raised intracranial pressure preventing any cerebral blood flow or, more commonly, the absence of systemic blood flow following abrupt or hypoxic circulatory cessation. The abrupt cessation of circulation leads to loss of consciousness and brain electrical activity; and when it becomes truly permanent and then irreversible, this becomes an operational definition of death. One must infer and decide that sufficient ischemic hypoxic injury has rendered the potential for reinstating any consciousness and brain stem function irreversibly lost. Progressive hypoxia that is seen in many patients after withdrawal of advanced physiologic support leads to apnea and then circulatory arrest. The outward sign of apnea that is then followed by circulatory arrest is the basis for inferring that irreversible loss of capacity for consciousness and self-awareness has occurred and that death can be identified has having occurred. The capacity for consciousness and self-awareness is the only irreplaceable emergent phenomenon—arising from physiologic function of the brain—that is necessary and sufficient to define the life of a person.

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