Brain death occurs when there is irreversible cessation of all functions of the entire brain, including the brain stem. It can be caused by conditions that lead to loss of oxygen to the brain like cerebral anoxia, hemorrhage or trauma. Diagnosing brain death involves assessing for the absence of brain stem reflexes and response to stimuli, as well as a positive apnea test where the patient fails to breathe independently with high carbon dioxide levels. Ancillary tests like EEG, angiography or PET scans may be used to confirm the diagnosis when clinical assessment is limited.
2. Brain Death
Out line
What is brain death?
Causes of Brain Death
Clinical evaluation of brain death
Brain Death Diagnosis
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3. Normal Brain Anatomy
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Cerebral Cortex
Brain Stem
Reticular
Activating
System
Receives multiple
sensory inputs
&
Mediates
Consciousness
(wakefulness)
5. Brain Stem : Functions
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Medulla
Cranial Nerve IX, X
Pharyngeal (Gag) Reflex
Tracheal (Cough) Reflex
Respiration
6. Death : Definition
Thanatology
Branch of science dealing with study of death
Death is the complete and irreversible stoppage of
Circulation
Respiration
Brain function (Tripod of life)
As long as oxygenated blood reaches brain stem, Life exists
….
Mechanical Ventilator use in ICU
Brought concept of “Brain Death”
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7. Brain Death
Ireversible destruction of the brain,with the
resulting total absence of all cortical and
brainstem functions,although spinal cord
refleves may remain
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9. 3 clinical findings necessary to confirm
irreversible cessation of all functions of the
entire brain, including brain stem
Coma (with a known cause)
Absence of brainstem reflexes
Apnoea
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13. Brain Death : Mechanism
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Neuronal Injury
Decreased Intracranial
Blood Flow
Neuronal Swelling
Increased Intracranial
Pressure
ICP > MAP is
incompatible
with life
14. 4 Steps in Determining
Brain Death
The Clinical Evaluation
The Neurologic Assessment
Ancillary Test
Documentation
15. Clinical evaluation of brain death
Irreversible coma
Known etiology and or reversible causes ruled out
Must have an absence of
Hypothermia (>32.50C)
Neuromuscular blockade and Shock
Significant levels of sedatives
Severe metabolic distrubance and Endocrine abnormalities
Poisoning
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16. Absence of cortical functions
No spontaneous movement, eye opening, or movement
or response after auditory, verbal, or visual commands
Cerebral motor response to pain
Supraorbital ridge, the nail beds, trapezius
Motor responses may occur spontaneously during
apnea testing (spinal reflexes)
Spinal arcs are intact!
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17. Absence of brain stem
function-1)Pupillary reflex
2)Corneal reflex
3)Gag reflex
4)Cough reflex
5)Oculocephalic reflex (doll’s eye reflex)
6)Oculovestibular reflex (caloric reflex)
7)No integrated motor response to pain
8)Apnea testing
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18. Pupillary reflex-
pupils may be midposition or dilated (4 to 9 mm)
Absent pupillary light reflex
IV atropine does not markedly affect response
Paralytics do not affect pupillary size
Topical administration of drugs and eye trauma may
influence pupillary size and reactivity
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19. Corneal reflex-
Corneal reflexes are absent in brain death
Corneal reflexes - tested by using a cotton-tipped
swab
.
There is no blink response to direct corneal stimulation.
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20. Oculocephalic reflex
Rapidly turn the head 90° on both sides
Normal response = deviation of the eyes to the
opposite side of head turning
Brain death = oculocephalic reflexes are absent (no
Doll’s eyes) = no eye movement in response to head
movement
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22. Vestibularocular reflex
No eye movements within 3 mints after irrigating each
tympanic membrane (if intact) sequentially with 50 ml
ice water for 30 to 45 seconds while the head of the
supine patient is elevated 30 degrees
Retained vestibulocular reflex
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23. Cold calorics interpretation
Not comatose
Nystagmus; both eyes slow toward cold, fast to midline
Coma with intact brainstem
Both eyes tonically deviate away cold water
No eye movement
Brainstem injury / death
Movement only of eye on side of stimulus
Internuclear ophthalmoplegia
Suggests brainstem structural lesion
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24. Brain Death : Apnoea Test
Pre-requisites
Body Temperature > 36° C
Systolic Blood Pressure ≥ 100 mm Hg
Normal Electrolytes profile
Normal PaCO2 (35-45 mm Hg)
Pre-Oxygenation
100% Oxygen via Tracheal Cannula for 10 min
Achieve PaO2 = 200 mm Hg
Monitor PaO2 with pulse oximetry
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25. Brain Death : Apnoea Test
Reduce Ventilation frequency to 10/min
Reduce PEEP to 5 Cm H2O
Take 1st Blood sample for Blood Gas analysis
Disconnect Ventilator
Deliver 100% O2 by catheter through ET tube
@ 6 L/min
Observe for Respiratory Movement
Atleast for 8 – 10 min
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26. Interpreting the test
The apnea test is POSITIVE (i.e., supports the
diagnosis of brain death) if:
There are no respiratory efforts during the test AND
Repeat ABG shows PCO2 > 60 mm Hg.
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27. Interpreting the test
The apnea test is INDETERMINATE if:
after 10 minutes, the patient demonstrates no
respiratory effort, but the PCO2 is < 60 mm Hg.
The apnea test is NEGATIVE (i.e., does NOT
support the diagnosis of brain death) if:
the patient demonstrates any respiratory effort at any
time during the test.
Cease the test and reconnect the ventilator immediately
upon observing respiratory effort.
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28. The Apnea Test
If the patient becomes unstable at any point
during the Apnea Test (i.e. SBP drops less than
90, significant desaturation on pulse-oximetry,
observance of cardiac arrhythmias, etc.), the test
should be aborted.
The Apnea Test should not “induce a code!”
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29. Movements originating from the spinal cord
or peripheral nerve which occur in brain
death
Spontaneous 'spinal' reflexes in the limbs
Respiratory-like movements
Sweating, blushing, tachycardia
Normal BP
Normal osmolar control mechanism
Deep tendon reflexes, Babinski's reflex
Facial myokymias
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30. Brain Death
Ancillary Confirmatory Testing
Recommended when
Proximate cause of coma is not known or
When confounding clinical conditions limit clinical
examination
EEG
Cerebral Angiography
PET : Glucose Metabolic Studies
Dynamic Nuclear Scan
Somato-Sensory Evoked Potential
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33. PET
Glucose Metabolism Studies
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“Hollow-skull sign”
of brain death
Cerebral metabolism
globally reduced ~50%
Normal
Nature Rev Neurosci 2005;6:899-909
34. Dynamic Nuclear Brain Scan
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“Hollow-skull sign” of brain death
NEJM 2001;344:1215-1221