Brain death presentation

1 May 2023 brain death

Brain death

Brain DeathOut 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 multiplesensory inputs

&Mediates

Consciousness(wakefulness)

Cerebral Cortex: Function


Cognition Voluntary Movement Sensation

Brain Stem : Functions


MedullaCranial 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”1 May 2023 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 fromBrain 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 reflexesApnoea

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 DeathAncillary 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 DeathConfirmatory Testing


Electro-Cerebral Silence

Normal

EEG

Brain DeathConfirmatory Testing


No Intra- Cranial Flow

Normal

Cerebral Angiography

PETGlucose 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

Health & Medicine

Brain death presentation