Snapshot A previously healthy 46-year-old female presents to the emergency department after a motor vehicle accident. The patient is unresponsive to noxious stimuli. Pupils are dilated and unresponsive to light. Oculovestibular and gag reflexes are absent. The patient is intubated due to loss of spontaneous respirations. After further workup, an apnea test is performed, which shows no respiratory response with a PaCO2 > 60 mm Hg. Introduction Irreversible brain function login to view 17 more bullets Etiologies Cardiopulmonary arrest login to view 1 more bullet Traumatic brain injury Subarachnoid hemorrhage Ischemic or hemorrhagic process login to view 1 more bullet Evaluation Clinical diagnosis login to view 2 more bullets Apnea testing login to view 7 more bullets Ancillary testing login to view 6 more bullets Differential Locked-in syndrome Hypothermia Drug intoxication Guillain-Barré syndrome