Brain Death

Mouhamad Ghyath Jamil, MD, FCCPCCM, Pulmonary & sleep Medicine

Director sleep Medicine unitDirector Home Mechanical Ventilation

Director Tele-ICUKing Faisal Specialist Hospital & Research Center

mecriticalcare.net

Background

President’s Commission report - 1981First formalized criteria for determination of

brain deathCriteria for adults

National Task Force – 1987Assembled 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 7 d – 2 mo = 48 hr and 2 EEG 2 mo – 1 yr = 24 hr and 2 EEG >1 yr = 12 hr, no EEG

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 ofHypothermia (>32.50C)Neuromuscular blockadeShock or significant hemodynamic instabilitySignificant levels of sedativesSevere metabolic distrubance

Basic exam 1 - Pain

Cerebral motor response to painSupraorbital ridge, the nail beds, trapeziusMotor 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 3Eye movement

Oculocephalic reflex = doll’s eyes

Oculovestibular reflex = cold caloric test

Oculocephalic reflex

Rapidly turn the head 90° on both sidesNormal 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

waterObserve 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; both eyes slow toward cold, fast to midline

Coma with intact brainstem Both eyes tonically deviate toward cold water

No eye movement Brainstem injury / death

Movement only of eye on side of stimulus Internuclear ophthalmoplegia Suggests brainstem structural lesion

Basic exam 4Facial sensory & motor responses Corneal reflexes are absent in brain death

Corneal reflexes - tested by using a cotton-tipped 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 5Pharyngeal and tracheal reflexes Both gag and cough reflexes are absent in

patients with brain deathGag 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 6Apnea

PaCO2 levels greater than 60 mmHg, ≥20 mmHg over baseline

Technique:Pre-oxygenate with 100% oxygen several minAllow baseline PaCO2 to be ~40 mmHg

Place pt on CPAP or bag-ETTObserve for respirations for ~6-10 minutesGet 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 so-called 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 aliveBrain dead pts have permanently lost the

capacity to think, be aware of self or surroundings, experience, or communicate with others

He’s in a comaReinforce 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 removedNOT when heart beat ceases

Do not say “kept alive” for organ donation Do not talk to the pt as if he’s still alive