ABSTRACT
This chapter considers patients in a coma and ventilated in a critical care unit. These patients may have been in a coma for a varying duration, and since dying is a process rather than an event, subtle changes or deterioration in neurology or new pathology may raise the possibility of the onset of "brain stem death (BSD)". The chapter describes the way tests are carried out in the United Kingdom and which cranial nerves (CNs) are tested at each point. Time of death is recorded as the time of absent brain stem reflexes at the end of the first set of tests. Brain stem death testing (BSDT) protocols may vary throughout the world. In some countries additional neurophysiological or imaging tests are used to confirm BSD. These can also be used if any uncertainty exists as to the nature of any metabolic or endocrine derangement or if routine testing as outlined in the previous section is not possible.
