Brain death (core), Organ donation (advanced) | May present after stroke, TBI, anoxic brain injury, etc All patients with severe brain injuries who are brain dead or likely to progress to brain death should be considered potential organ donors → referral to local organ procurement organization | Brain death = irreversible, catastrophic brain injury causing total cessation of brain function Criteria for brain death declaration: - Irreversible, unresponsive coma with known cause - Exclude potentially reversible medical conditions (ie, acid-base or electrolyte derangements, endocrine function, paralytic or CNS depressant meds, hypothermia, etc) - Brain death exam Fixed and dilated pupils Absence of brainstem reflexes—corneal, oculocephalic, oculovestibular, gag, cough No motor response to noxious stimuli No spontaneous respirations Some states require two brain death exams by different physicians with defined time interval between the two - Confirmatory apnea test—the most definitive finding supporting the diagnosis of brain death PaCO2 normalized to 40 mm Hg, patient preoxygenated with 100% FiO2 and then disconnected from ventilator and placed on 100% FiO2 delivered passively to ETT via T-piece ABG drawn after ~10 min If there is no evidence of spontaneous respiratory activity, PaCO2 ≥ 60 mm Hg, and pH is acidotic, this is considered evidence of brain death If there is any evidence of respiratory activity, patient is not brain dead, return to vent immediately Apnea test not valid for patients with cervical fracture above C4 or on substances that depress respiratory drive - Adjuncts: Cerebral angiography (gold standard), cranial doppler, CTA, MRA, and nuclear cerebral blood flow scan Donation after cardiac death—a way for patients with severe brain injury who do not technically meet the criteria for brain death to be donors Must have family consent before patient can be an organ donor | Patients with severe brain injury develop physiologic derangements that must be treated to prevent cardiovascular collapse and loss of useable organs - Autonomic dysregulation → profound vasodilation and hypotension - Depletion of ADH → diabetes insipidus → inappropriate diuresis, hypovolemia, hyperosmolality, and hypernatremia Without intervention, brain death is usually followed by severe injury to all organs and circulatory collapse within 48 h | | | |