Transcript Brain Death - Mecriticalcare.net

Brain Death
Mouhamad Ghyath Jamil, MD, FCCP
CCM, Pulmonary & sleep Medicine
Director sleep Medicine unit
Director Home Mechanical Ventilation
Director Tele-ICU
King Faisal Specialist Hospital & Research Center
mecriticalcare.net
Background

President’s Commission report - 1981
 First
formalized criteria for determination of
brain death
 Criteria

for adults
National Task Force – 1987
 Assembled
to recommend guidelines for the
determination of cerebral death in children
1987 Task force Recommendations






Presence of coma and apnea
Absent brainstem function
Absent oculocephalic and oculovestibular reflexes
No cough, gag or corneal reflexes
Spinal arcs could be present
Time delay between exams recommended based
on patient age
d – 2 mo = 48 hr and 2 EEG
 2 mo – 1 yr = 24 hr and 2 EEG
 >1 yr = 12 hr, no EEG
7
Definition


Coma: A state of unconsciousness from which the
patient cannot be aroused even with stimulation such as
pressure on the supraorbital nerve, temporomandibular
angle of the mandible, sternum, or nailbed
Irreversible coma: Coma wherein reversible causes such
as acid-base, electrolyte, endocrine disturbances,
hypothermia (core temperature < 32°C), drug
intoxication, hypotension, poisoning, and
pharmacological neuromuscular blockade have been
ruled out as potential causes or contributors
Criteria for CNS Determination of
Death (Brain Death)
Irreversible coma
 Absence of cortical function
 Absence of brainstem function
 Apnea
 2 examinations with interval according to
patient’s age
 Ancillary tests

Irreversible Coma
Known etiology and or reversible causes
ruled out
 Must have an absence of

(>32.50C)
 Neuromuscular blockade
 Shock or significant hemodynamic instability
 Significant levels of sedatives
 Severe metabolic distrubance
 Hypothermia
Basic exam 1 - Pain

Cerebral motor response to pain
 Supraorbital
ridge, the nail beds, trapezius
 Motor responses may occur spontaneously
during apnea testing (spinal reflexes)
 Spinal reflex responses occur more often in
young
 If pt had NMB, then test w/ train-of-four

Spinal arcs are intact!
Basic exam 2 - Pupils



Round, oval, or irregularly shaped
Midsize (4-6 mm), but may be totally dilated
Absent pupillary light reflex
 Although
drugs can influence pupillary size, the light
reflex remains intact only in the absence of brain death
 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
 Pre-existing ocular anatomic abnormalities may also
confound pupillary assessment in brain death
Pupils fixed and unresponsive to light.
Basic exam 3
Eye movement

Oculocephalic reflex = doll’s eyes

Oculovestibular reflex = cold caloric test
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

Not Barbie, but old fashioned type dolls
Cold calorics
Elevate the HOB 30°
 Irrigate one tympanic membrane with iced
water

 Observe
pt for 1 minute after each ear
irrigation, with a 5 minute wait between testing
of each ear
 Facial trauma involving the auditory canal and
petrous bone can also inhibit these reflexes
Eyes do not deviate toward cold water
instilled into an auditory canal.
Cold calorics interpretation

Not comatose
 Nystagmus;

Coma with intact brainstem
 Both

eyes tonically deviate toward cold water
No eye movement
 Brainstem

both eyes slow toward cold, fast to midline
injury / death
Movement only of eye on side of stimulus
 Internuclear
ophthalmoplegia
 Suggests brainstem structural lesion
Basic exam 4
Facial sensory & motor responses

Corneal reflexes are absent in brain death
 Corneal
reflexes - tested by using a cottontipped swab
 Grimacing in response to pain can be tested
by applying deep pressure to the nail beds,
supraorbital ridge, TMJ, or swab in nose
 Severe facial trauma can inhibit interpretation
of facial brain stem reflexes
There is no blink response to direct corneal
stimulation.
Basic exam 5
Pharyngeal and tracheal reflexes

Both gag and cough reflexes are absent in
patients with brain death
 Gag
reflex can be evaluated by stimulating
the posterior pharynx with a tongue blade, but
the results can be difficult to evaluate in orally
intubated patients
 Cough reflex can be tested by using ETT
suctioning, past end of ETT
There is no gag or cough reflex.
Basic exam 6
Apnea
PaCO2 levels greater than 60 mmHg, ≥20
mmHg over baseline
 Technique:

 Pre-oxygenate
with 100% oxygen several min
 Allow baseline PaCO2 to be ~40 mmHg
 Place pt on CPAP or bag-ETT
 Observe for respirations for ~6-10 minutes
 Get ABG to determine PaCO2
Confirmatory testing

4 vessel angiography

EEG
 30

minutes
Cerebral blood flow = perfusion scan
Cerebral perfusion scan
Blood flow is absent in the cranial vault
when examined by cerebral scintigraphy
(shown) or angiography.
Kids over 1 year old

Absence of all brain and brainstem function
 Comatose: no purposeful response to any stimulus
 Brainstem function is absent when:
 Pupils are mid-position and do not react to light
 Eyes does not blink when touched (corneal reflex)
 Eyes do not rotate in the socket when the head is moved from
side to side (oculocephalic reflex).
 Eyes do not move when ice water is placed in the ear canal
(oculovestibular reflex)
 Child does not cough or gag when a suction tube is placed
deep into the breathing tube
 Child does not breathe when taken off the ventilator

Repeat in ~6 hours
Children under 1 year

Necessary to repeat the clinical examination after
an ‘appropriate’ observation period has passed
Age 7 days to 2 months
Two examinations 48 hours apart and one EEG
Age 2 months-1 year
Two examinations 24 hours apart and one EEG or
perfusion scan

Confirmatory EEG unless it is determined that
there is no blood flow to the brain
Clinical Pearls and Pitfalls


Damage to the base of the pons, typically from a basilar
artery embolism, can result in the development of the socalled locked-in syndrome, where the patient loses all
voluntary movements with the exception of blinking and
vertical eye movements.
Guillain-Barre syndrome can involve all peripheral and
cranial nerves and mimic brain death, but can be
differentiated from it by the time course of the
development of the disease which evolves over several
days and by electrical and blood flow examinations.
Clinical Pearls and Pitfalls


Hypothermia must be reversed prior to performance of the clinical
examination to eliminate the confounding effects on the clinical
examination.
A variety of drugs including narcotics, benzodiazepines, tricyclic
antidepressants, anticholinergics, and barbiturates can mimic brain
death. It is prudent to administer reversal agents where the cause of
coma is unknown and the agents are available (ie, naloxone,
flumazenil). Alternatively, where drug levels are available, brain
death should not be declared until the levels of these agents are
subtherapeutic. If the serum level of a drug cannot be determined,
declaration of brain death should not be done until several
elimination half-lives have passed without change in the patient's
examination.
Clinical Pearls and Pitfalls




The cold-caloric oculocephalic examination can be confounded by
wax or blood in the ear canal.
Doll's eyes examination should not be performed if the cervical
spine is unstable.
Chronic obstructive pulmonary disease or sleep apnea may result in
elevated baseline CO2 retention, confounding the apnea
examination.
Certain spinal reflexes including spontaneous movements of the
torso, arms, or toes may mimic volitional movements, but should be
ignored if the clinical brain stem examination is consistent with brain
death or confirmatory examinations are positive.
Common misconceptions

Since there is a heartbeat, he is alive
 Brain
dead pts have permanently lost the
capacity to think, be aware of self or
surroundings, experience, or communicate with
others

He’s in a coma
 Reinforce

that they are dead
With rehab/time he’ll get better
 Irreversible,
dead brain cells do not regrow
How to make it clear
Say “dead”, not “brain dead”
 Say “artificial or mechanical ventilation”,
not “life support”
 Time of death = neurologic determination

 NOT
when ventilator removed
 NOT when heart beat ceases
Do not say “kept alive” for organ donation
 Do not talk to the pt as if he’s still alive

www.mecriticalcare.net