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Controversies in defining and determining death in critical care
James L. Bernat
Abstract | Circulatoryrespiratory or brain tests are widely accepted for definition and determination of death, but have several controversial issues. Both determinations have been stimulated by organ donation, but must be valid independently of this process. Current controversies in brain death include whether the definitionis conceptually coherent, whether the whole-brain or brainstem criterion is correct, whether one neurological examination or two should be required, and when to conduct the examination following therapeutic hypothermia. Controversies about the circulatory determination of death include the minimum duration of asystole that is sufficient for death to be declared, and whether the distinction between permanent and irreversible cessationof circulatory functioning is important. In addition, the goal of organ donation raises issues such as the optimal way to time and conduct the request conversation with family members of the patient, and whether the Dead Donor Rule should be abandoned.
Bernat, J.L. Nat. Rev. Neurol. 9, 164173 (2013); published online 19 February 2013; http://www.nature.com/doifinder/10.1038/nrneurol.2013.12
Web End =doi:10.1038/nrneurol.2013.12
Introduction
Contemporary controversies about brain and circulatory determinations of death in the intensive care unit (ICU) can be informed by studying the historical impact of life-sustaining therapies (LSTs) on the definition of human death.1 Prior to development of LSTs
particularly tracheal positive-pressure ventilation (TPPV) and cardio-pulmonary resuscitation (CPR)in the 1950s, death was a unitary phenomenon. When illness or injury caused cessation of one of the three vital functions critical to lifecirculation, respiration and brain functionboth of the others ceased within minutes. This inter dependence of vital functions, and the inability of physicians to intervene to restore or support them, made the definition of death straight forward, although its determination was incorrect at times.2
The development of LSTs abolished the unitary nature of death, as the new technologies could support or restore individual vital functions while others remained absent.3 CPR could reverse cardiac arrest and restore circulation, vasopressors could maintain blood pressure in shock, and TPPV could support ventilation in apnoea. These LSTs were valuable interventions when they led to restoration of normal function, but were harmful when they restored circulation and supported ventilation in patients in whom all brain functions had ceased irreversibly. The concept of a brain-based determination of death...