Sunday, November 9, 2014

Determining Brain Death: Legal Definition and Original Guidelines

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Sean Weaver, DO MPH
Emergency Medicine Resident
University of Nevada, School of Medicine

The following blog post appeared initially at and is reproduced with the permission of the author.  


Brain death accounts for 1-2% of all deaths in the United States.[1] Patients will present to your emergency department clinically brain dead. While neurologists, neurosurgeons and intensivists may have more experience in determining brain death, all physicians have the legal authority to determine brain death.[2] As emergency physicians we need to know how to properly evaluate these patients, assess their level of brain function, guide their disposition, and prepare their family or loved ones for the eventual outcome.

Legal Definition
The legal definition of death was established in 1980 by the Uniform Determination of Death Act (UDDA). A group of lawyers and lawmakers met for 7 days in Kauai, Hawaii and decided on the follow definition of brain death:

“An individual who has sustained either [1] Irreversible cessation of circulatory and respiratory function, or [2] Irreversible cessation of all functions of the entire brain, including the brain stem, is dead. A determination of death must be made with acceptable medical standards.”[3]

While this law created a legal term of death, there was appropriately no clarification regarding “acceptable medical standards.”

Original Acceptable Medical Standards for Declaring Brain Death [4]
In 1995 the American Academy of Neurologists published practice parameters regarding declaration of brain death. These guidelines are worth knowing, and have been upheld in subsequent studies. Here is a summary of their recommendations:

Brain Death Criteria
Definition: absence of clinical brain function when the proximate cause is known and demonstrably irreversible.
  • Clinical or neuroimaging evidence of acute CNS catastrophe
  • No confounding medical condition
  • No drug intoxication
  • Core temp > 90 deg F

Three Cardinal Signs of Brain Death: Coma, Absence of Brain Stem Reflexes, and Apnea
  1. Coma or unresponsiveness: no cerebral motor response to pain
  2. No brain stem reflexes
    • No occulocephalic testing: dolls eye
    • No deviation of eyes to 50 mL of cold water irrigation in each ear
  3. Lack of facial sensation and facial motor response
    • No corneal reflex to touch
    • No jaw reflex
    • No grimace to deep pressure of the supraorbital ridge or TMJ 
  4. Pharyngeal and tracheal reflexes
    • No response after stimulation of posterior pharynx with a tongue blade
    • No cough to bronchial suctioning
  5. Apnea testing: prerequisites
    • Core temp ≥ 36.5 deg C or 97 deg F
    • SBP ≥90mmHg
    • Euvolemic
    • Normal PCO2: option of arterial PCO2 >40mmHg
    • Normal PO2: option of preoxygenation to obtain arterial PO2 ≥200mmHg
  6. Apnea Testing: process
    • Deliver 100% O2 either directly into the trachea or by placing a cannula a the level of the carina
    • Connect a pulse ox (if not done already) and disconnect the ventilator
    • Get an ABG 8 minutes after the ventilator has been disconnected: goal is to obtain PaO2, PaCO2 and pH
    • Reconnect the ventilator
    • If respiratory movements are absent and PaCO2 is 60mmHg the apnea test is positive
    • If respiratory movements are observed, the apnea test result is negative. Repeat the test
    • If during testing the SBP is ≤90mmHg or pulse ox indicates significant O2 desaturation or if cardiac arrhythmias develop immediately obtain an ABG. If PaCO2 is ≥60mmHg or PaCO2 is increased by 20mmHg over baseline the apnea test is positive. If PaCO2 is <60mmHg or PaCO2 is <20mmHg over baseline normal PaCO2 the test is indeterminate.
  7. Pitfalls
    • Severe facial trauma
    • Preexisting pupillary abnormalities
    • Toxic levels of sedative drugs, aminoglycosides, TCA’s, etc.
    • Sleep apnea or severe pulmonary disease resulting in chronic CO2 retention
Observations That Do Not Exclude Brain Death
  • Spontaneous movement of limbs
  • Respiratory like movements
  • Sweating, blushing, tachycardia
  • Normal blood pressure or sudden increases in blood pressure
  • DTR’s
  • Babinski reflex
Next week we will review updated recommendations from the American Academy of Neurologists to determine brain death. Additionally we will review ancillary tests that the emergency medicine physician may be asked to order.

  1. Spinello IM. Brain Death Determination. J Intensive Care Med. 2013.
  2. Wijdicks EF, Varelas PN, Gronseth GS, Greer DM. Evidence-based guideline update: determining brain death in adults: report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology. 2010;74(23):1911-8. 
  3. Available at: Accessed June 27, 2014.
  4. Practice parameters for determining brain death in adults (summary statement). The Quality Standards Subcommittee of the American Academy of Neurology. Neurology. 1995;45(5):1012-4.

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