5Background President’s Commission report - 1981 First formalized criteria for determination of brain deathCriteria for adultsNational Task Force – 1987Assembled to recommend guidelines for the determination of cerebral death in children
61987 Task force Recommendations Presence of coma and apneaAbsent brainstem functionAbsent oculocephalic and oculovestibular reflexesNo cough, gag or corneal reflexesSpinal arcs could be presentTime delay between exams recommended based on patient age7 d – 2 mo = 48 hr and 2 EEG2 mo – 1 yr = 24 hr and 2 EEG>1 yr = 12 hr, no EEGSince this task force, there has been research into the determination of brain deathMost centers have a slight variation on the earlier recommendations
7DefinitionComa: 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 nailbedIrreversible 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
8Criteria for CNS Determination of Death (Brain Death) Irreversible comaAbsence of cortical functionAbsence of brainstem functionApnea2 examinations with interval according to patient’s ageAncillary tests
9Irreversible 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
10Basic exam 1 - Pain Cerebral motor response to pain Supraorbital ridge, the nail beds, trapeziusMotor responses may occur spontaneously during apnea testing (spinal reflexes)Spinal reflex responses occur more often in youngIf pt had NMB, then test w/ train-of-fourSpinal arcs are intact!
11Basic exam 2 - Pupils Round, oval, or irregularly shaped Midsize (4-6 mm), but may be totally dilatedAbsent pupillary light reflexAlthough drugs can influence pupillary size, the light reflex remains intact only in the absence of brain deathIV atropine does not markedly affect responseParalytics do not affect pupillary sizeTopical administration of drugs and eye trauma may influence pupillary size and reactivityPre-existing ocular anatomic abnormalities may also confound pupillary assessment in brain deathFixed/dilated – 3rd nerve compression (herniation, midbrain lesion)Pinpoint = pontine lesion
14Basic exam 3 Eye movement Oculocephalic reflex = doll’s eyesOculovestibular reflex = cold caloric test
15Oculocephalic reflex Rapidly turn the head 90° on both sides Normal response = deviation of the eyes to the opposite side of head turningBrain death = oculocephalic reflexes are absent (no Doll’s eyes) = no eye movement in response to head movementNot Barbie, but old fashioned type dolls
17Cold 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 earFacial trauma involving the auditory canal and petrous bone can also inhibit these reflexes
18Eyes do not deviate toward cold water instilled into an auditory canal.
20Cold calorics interpretation Not comatoseNystagmus; both eyes slow toward cold, fast to midlineComa with intact brainstemBoth eyes tonically deviate toward cold waterNo eye movementBrainstem injury / deathMovement only of eye on side of stimulusInternuclear ophthalmoplegiaSuggests brainstem structural lesionIce water to the right ear inhibits the right vestibular system and allows the normal left vestibular system to drive the eyes to the right (NORMAL RESPONSE)
21Basic exam 4 Facial sensory & motor responses Corneal reflexes are absent in brain deathCorneal reflexes - tested by using a cotton-tipped swabGrimacing in response to pain can be tested by applying deep pressure to the nail beds, supraorbital ridge, TMJ, or swab in noseSevere facial trauma can inhibit interpretation of facial brain stem reflexesCorneal reflex tests integrity of CN 5 (sensory) and CN 7 (motor); watch medial lower eyelid/lashes for movementNasal stimulation should elicit a grimace and tests CN 7
22There is no blink response to direct corneal stimulation.
23Basic exam 5 Pharyngeal 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 patientsCough reflex can be tested by using ETT suctioning, past end of ETT
25Basic exam 6 ApneaPaCO2 levels greater than 60 mmHg, ≥20 mmHg over baselineTechnique:Pre-oxygenate with 100% oxygen several minAllow baseline PaCO2 to be ~40 mmHgPlace pt on CPAP or bag-ETTObserve for respirations for ~6-10 minutesGet ABG to determine PaCO2
28Blood flow is absent in the cranial vault when examined by cerebral scintigraphy (shown) or angiography.
29Kids over 1 year old Absence of all brain and brainstem function Comatose: no purposeful response to any stimulusBrainstem function is absent when:Pupils are mid-position and do not react to lightEyes 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 tubeChild does not breathe when taken off the ventilatorRepeat in ~6 hours
30Children under 1 yearNecessary to repeat the clinical examination after an ‘appropriate’ observation period has passedAge 7 days to 2 monthsTwo examinations 48 hours apart and one EEGAge 2 months-1 yearTwo examinations 24 hours apart and one EEG or perfusion scanConfirmatory EEG unless it is determined that there is no blood flow to the brain
31Clinical 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.
32Clinical 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.
33Clinical 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.
34Common 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 othersHe’s in a comaReinforce that they are deadWith rehab/time he’ll get betterIrreversible, dead brain cells do not regrow
35How to make it clear Say “dead”, not “brain dead” Say “artificial or mechanical ventilation”, not “life support”Time of death = neurologic determinationNOT when ventilator removedNOT when heart beat ceasesDo not say “kept alive” for organ donationDo not talk to the pt as if he’s still alive
36Organ donation Call regional transplant coordinator for all deaths Donor or not in your eyesTissue – bone, corneas, heart valvesDo not mention organ donation to family“LifeLink” will approach them after the child is declaredIf family asks you about donationAcknowledge that it is a wonderful gift they are consideringTell them you will contact “LifeLink” to have them available for questionsContact “LifeLink” ASAP
37Clinical tests Absence of motor responses to painful stimuli. — Absence of light reflex on pupillary examination (no pupillary constriction to bright light) and pupils fixed in midposition or dilated 4 to 9 mm in diameter (Figure 14-1). —Absence of doll's eyes, that is, no compensatory eye movement in response to rapid rotation of the head to either side.Absence of oculovestibular response on cold-caloric examination, wherein the tympanum is irrigated with ice water after the head has been tilted to 30 (to make the auditory canal vertical so that it will fill with cold water)—no eye deviation toward cold stimulus (Figure 14-2).Absence of corneal reflex, that is, no blinking (Figure 14-3) when the cornea is touched (with a cotton swab or pledget). —Absence of gag reflex (Figure 14-4). —
38Absence of cough on suctioning or movement of the endotracheal tube. — Apnea test: Absence of spontaneous respiratory effort in response to a Paco2 that is 60 mm Hg or 20 mm Hg greater than patient's normal baseline value. —The test is typically performed after disconnection from the mechanical ventilator to avoid factitious breath sensing by ventilator sensors. —The patient is typically preoxygenated with 100% oxygen prior to test to eliminate pulmonary stores of nitrogen and thereby reduce the possibility that the patient's hemoglobin oxygenation saturation will drop during apnea test (necessitating premature stopping of the test) prior to achievement of the threshold CO2 level.
39Confirmatory testsCerebral angiography should show no intracerebral filling from either the carotid or vertebral arteries, but the external carotid circulation should be patent.Electroencephalography should demonstrate no reactivity to somatosensory or audiovisual stimuli.Transcranial Doppler ultrasound should show absent diastolic flow with small early systolic peaks.Cerebral technetium scan should show the absence of intracranial filling (Figure 14-5).
40Brain deathA patient meets the criteria for brain death following the performance of sequential (the interval is arbitrary, but a 6-hour interval is typical when the cause of coma is known, while a longer interval may be appropriate when the cause is undetermined) clinical examinations by a qualified examiner (typically an intensivist, neurologist, or neurosurgeon) consistent with brain death.The interval between sequential examinations may be shortened if there is a confirmatory test consistent with brain death