Brain death presentation

Brain death
24 May 2016 brain death

Brain Death
Out line
 What is brain death?
 Causes of Brain Death
 Clinical evaluation of brain death
 Brain Death Diagnosis

Normal Brain Anatomy
Cerebral Cortex
Brain Stem
Reticular
Activating
System
Receives multiple
sensory inputs
&
Mediates
Consciousness
(wakefulness)

Cerebral Cortex: Function
 Cognition
 Voluntary Movement
 Sensation

Brain Stem : Functions
Medulla
Cranial Nerve IX, X
 Pharyngeal (Gag) Reflex
 Tracheal (Cough) Reflex
Respiration

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”

Brain Death
 Ireversible destruction of the brain,with the
resulting total absence of all cortical and
brainstem functions,although spinal cord
refleves may remain

Conditions Distinct from
Brain Death
 Coma
 Persistent Vegetative State
 Locked in Syndrome

 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

Causes: Brain Death
Normal Cerebral Anoxia

Causes: Brain Death
Normal
Cerebral
Haemorrhage

Causes: Brain Death
Normal Cerebral Trauma

Brain Death : Mechanism
Neuronal Injury
Decreased Intracranial
Blood Flow
Neuronal Swelling
Increased Intracranial
Pressure
ICP > MAP is
incompatible
with life

4 Steps in Determining
Brain Death
 The Clinical Evaluation
 The Neurologic Assessment
 Ancillary Test
 Documentation

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

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!

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

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

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.

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

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

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

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

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

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.

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.

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!”

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

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

Brain Death
Confirmatory Testing
Electro-Cerebral SilenceNormal
EEG

Brain Death
Confirmatory Testing
No Intra- Cranial FlowNormal
Cerebral Angiography

PET
Glucose Metabolism Studies
“Hollow-skull sign”
of brain death
Cerebral metabolism
globally reduced ~50%
Normal
Nature Rev Neurosci 2005;6:899-909

Dynamic Nuclear Brain Scan
“Hollow-skull sign” of brain death
NEJM 2001;344:1215-1221

Brain death presentation

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