Brain Death







  • A.

    Brain death is defined, in the United States and many other countries, as permanent and irreversible cessation of whole brain function. Some countries, such as the United Kingdom, consider loss of all brainstem function sufficient to meet criteria for brain death. Brain death is a clinical diagnosis and, in localities that recognize the determination, is legally equivalent to death from permanent cessation of cardiac function. While various guidelines exist for determination of brain death, practice is determined by local law and by institutional policy. It is therefore incumbent upon the physician to know and to follow these.


  • B.

    Examples of etiologies sufficient to account for loss of whole brain function include global hypoxic-ischemic injury and herniation from severe cerebral edema or hydrocephalus.


  • C.

    The concept of brain death is frequently confusing to both physicians and the lay public. While permission to determine brain death is generally not required, it is good practice to educate families about the concept of brain death and to describe the process of brain-death determination.


  • D.

    Some institutions require two clinical examinations separated by a waiting period, while others require only a single examination. An examination that is consistent with brain death establishes that the patient is comatose and lacks all brainstem reflexes, including spontaneous breathing. The following examination elements should be assessed and documented:




    • Coma – there should be no motor responses to pain except for reflexes mediated by the spinal cord.



    • Pupillary light reflex – the pupils should be nonreactive to bright light.



    • Corneal reflexes – there should be no reflex eye closure when the corneas are touched with a gauze.



    • Oculocephalic reflexes – there should be no reflex movement of the eyes when the head is turned. This test should be deferred in patients with known or suspected instability of the cervical spine.



    • Oculovestibular reflexes – there should be no movement of the eyes after instillation of cold water into each external auditory canal.



    • Cough – there should be no cough when the carina is stimulated with a deep suction catheter.



    • Gag – there should be no gag when the posterior pharynx is stimulated with a tongue depressor or firm plastic suction tip.



    • Spontaneous breathing – there should be no patient-initiated breaths on the mechanical ventilator. Spontaneous breathing is also tested more rigorously by a formal apnea test.



  • E.

    In general, confirmatory studies are not required to determine brain death. However, under certain circumstances and in some areas, confirmatory testing may be mandated. When portions of the clinical examination cannot be completed (e.g., due to severe facial trauma), confirmatory testing is indicated. Confirmatory tests might include a nuclear blood flow scan or a catheter cerebral angiogram showing no cerebral blood flow, or a brain-death protocol electroencephalogram showing no cerebral electrical activity.


  • F.

    Formal apnea testing should be performed and aims to demonstrate absent function of medullary breathing centers. Typically, after a brief period of preoxygenation, the patient is removed from the ventilator and observed for 10–15 minutes. An apnea test is considered consistent with brain death if the patient makes no respiratory effort and the patient’s arterial partial pressure of carbon dioxide rises from a normal baseline to > 60 mmHg or to 20 mmHg above baseline.




May 3, 2021 | Posted by in NEUROLOGY | Comments Off on Brain Death

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