Controversies in defining and determining death in critical care.

Circulatory-respiratory 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 definition is 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 cessation of 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.