3. CICM Fellowship exam /2012
With regards to the determination of brain death:
1. Apart from identifying evidence of sufficient intracranial pathology, list the
preconditions that must be met prior to the determination of brain death by clinical
criteria:
2. What is the recommended minimum time for observation in cases of hypoxic-
ischaemic brain injury, prior to performing clinical testing of brain-stem function?
3. For each of the following brainstem reflexes, list the cranial nerves that are tested:
a. Cough reflex
b. Vestibulo-ocular reflex
c. Pupilary light reflex
d. Corneal reflex
e. Gag reflex
4. List three contraindications to performing apnoea testing:
5. List the acceptable imaging techniques that may be used to demonstrate brain
death as an alternative to clinical testing as recommended by the ANZICS Statement
on Death and Organ Donation
4. Which of the following precludes
certification of death by clinical brain
death testing?
• A) Flexion of the right elbow on painful
stimulus within the cranial nerve distribution
• B) Unilateral hemotympanum
• C) No family consent
• D) Isolated Brainstem infarction without
cerebral injury
• E) Avulsion of one eye
5. Brain Death
• Brain death occurs in the setting of a severe brain
injury associated with marked elevation of
intracranial pressure.
• Inadequate perfusion pressure results in a cycle
of cerebral ischaemia and oedema and further
increases in intracranial pressure.
• When intracranial pressure reaches or exceeds
systemic blood pressure, intracranial blood flow
ceases and the whole brain, including the brain-
stem dies.
6. • Determination of brain death requires that
there is unresponsive coma, the absence of
brain-stem reflexes and the absence of
respiratory centre function.
• These findings are irreversible.
• In particular, there must be definite clinical or
neuro-imaging evidence of acute brain
pathology consistent with the irreversible loss
of neurological function.
7. • Brain death cannot be determined without evidence of
sufficient intracranial pathology.
• Cases in which brain-stem has been the primary site of
injury and death of the brain-stem has occurred
without death of the cerebral hemispheres.
• Thus brain death cannot be determined when the
condition causing coma, and loss of all brain stem
functions has affected only the brain stem, and there is
still blood flow to the supratentorial part of the brain.
• Whole brain death is required for the legal
determination of death in Australia and NZ. (cf to the
UK.)
8. • The 3 essential findings in brain death are
– Coma(unresponsiveness)
– Absence of brainstem reflexes
– Apnoea
9. Brain death determination
• Clinical testing if preconditions are met
• Imaging that demonstrates the absence of
intracranial blood flow.
• There is no documented case of a person who fulfills the preconditions
and criteria for brain death ever subsequently developing any return of
brain function.
10. Determination of Brain death by
clinical examination
• Preconditions
– Evidence of sufficient intracranial pathology
• ALL the following preconditions must be met if brain
death is to be determined by clinical examination.
– cause for coma consistent with brain death
– at least 4 hours of observation during which preconditions
must be met (GCS 3, pupil non-reactive, no cough, apnoea)
– neuro-imaging consistent with acute brain pathology that
could cause brain death
– normothermia (T>35C)
11. Brain death preconditions
• normotension (SBP>90 or MAP>60mmHg in an adult)
• no sedation or analgesia (dependent on types of drugs
used, renal and hepatic function; use antagonists if
concerned)
• absence of severe electrolyte, metabolic and endocrine
disturbances (glucose, Na+, PO43-, Mg2+, renal and hepatic
function)
• no paralysis (use NMJ monitor or electromyography if
concerned)
• ability to assess brain stem reflexes (at least one eye and
ear)
• ability to perform apnoea test (doesn’t have severe hypoxic
respiratory failure or have a high cervical spine injury)
12. • In cases of acute hypoxic ischaemic brain injury, clinical
testing for brain death be delayed for at least 24 hours
subsequent to ROSC.
• Therapeutic hypothermia may modify outcome
prediction after cardiac arrest.
• It is therefore recommended when induced
hypothermia has been used after resuscitation from
cardiorespiratory arrest that clinical testing for brain
death be delayed for at least 24 hours AFTER
rewarming.
• Brain death may be determined PRIOR to 24 hours by
demonstration of absent cerebral blood flow.
14. “It’s about testing connections”
• GCS 3 – no response in CN distribution (supraorbital
compression) and deep nail bed pain in all four limbs
• !!Spinal reflexes may be present in patients with brain
death
• Observations that are incompatible with brain death
– Decerebrate/decorticate posturing
– True extensor or flexor motor responses to painful stimuli
– Seizures
15. Brain Stem Reflexes testing
ALL MUST BE ABSENT
• pupils fixed, no reaction to light (CN II, III) –
must be > 4mm
• !! Anticholinergic drugs such as atropine can
cause pupillary dilatation
• Cataract or iris surgery is not a CI for clinical
testing
16. • no corneal reflex (CN V, VII)
• !! Touching the sclera is not sufficient
17. • Reflex response to pain in the trigeminal nn
distribution- CN V-VII
18. • no oculo-vestibular reflexes (CN III, IV, VI, VIII)
• !! Ruptured eardrums does not invalidate test
• # to BOS or petrous temporal bone may
obliterate the response on the side of the #
• Testing for the oculocephalic reflex – submaximal
stimulus/aggravate spinal injury
21. • no cough (CN X)
• !! Efferent nerves are the phrenic/innovation
of the thoracic and abdominal musculature.
Therefore it cannot be assessed in patients
with high cervical cord injury.
22. • positive apnoea test (after preoxygenation,
and pH 7.3, no breath taken after
disconnection from ventilator with a PaCO2 >
60mmHg; or increase in PCO2 by 20 mmHg if
COPD/ CO2 retainer)
Apnoea test
23. • independent examination by 2 suitably trained
and experienced doctors
• can be sequential (don’t have to wait 2 hours
between testing)
• time of death is the time of completion of the
second examination
24. Brain Death Investigations
• the indication for cerebral perfusion imaging is
when clinical brain death can not be
determined (any of the preconditions can not
be met)
• an investigation showing absent cerebral
parenchymal blood flow is required
25. • Problematic in
– Infants
– Massive skull fractures
– Craniotomy with extensive bone removal
28. ANZICS recommendation
• 4 vessel angiography
• Radionuclide imaging
• CT A may be acceptible, although experience
in the technique is limited.
• MRI and TCD are not recommended.
29. 4 vessel cerebral angiography
• Gold standard of confirmatory tests.
• No false positives reported.
• False negative examinations may occur if
– No significant elevation of the ICP
– Contrast is injected too vigorously into the
downstream circulation, thereby artifactually
opacifying the intracranial vasculature. (?screen
with TCD)
30. 4 vessel angiography
• Advantages
– Able to visualise cerebral and posterior fossa
blood flow
– Gold standard
• Disadvantages
– Invasive
– Expensive
– Exposed donor to toxic contrast material
– False negatives
32. Tc-99 HMPAO SPECT radionuclide
• Absence of intracranial perfusion.
• IV bolus of radioactive material Crosses BBB to
be retained in the parenchyma
• There are occasional technical failures due to
inadequate bolus injection of the
radiopharmaceutical.
• Single Photon Emission CT(SPECT) provides
superior imaging in adults and in children Vs
2-planar imaging
33. • Advantages:
– ?Ability to detect blood flow patients who are in a
coma due to drug intoxication.
• Disadvantages:
– Posterior fossa circulation not evaluated
– Occasional technical failure- inadequate bolus
injection of the radiopharmaceutical.
35. CT angiography
• Small studies have shown absent enhancement
bilaterally of peripheral intracranial arteries and central
veins on CTA at 60 secs. There should be absent
enhancement bilaterally on ALL these
– MCA cortical branches- that is beyond the sylvian branches
– P2 segment of the posterior cerebral arteries
– Pericallosal arteries
– Internal cerebral veins
• to perform this examination, the potential risk of
contrast-mediated tissue injury is still present
36. CT angiography
• No large studies with matched controls
• When compared to clinical testing for brain
death, the CTA test had a sensitivity of 0.85
• (Cochrane systematic review -The use of
computed tomography angiography (CTA) to
confirm the clinical diagnosis of brain death
Taylor et al 31.3.2014
37. CT angiography
• Advantages
– Cheap, easily accessible
– Only needs IV access
• Disadvantages
– Low overall sensitivity-0.85
– Contrast mediated toxicity to donor organs
38. Transcranial Duplex US
• Classical findings in a patient who is brain
dead are short systolic spikes or peaks,
oscillating movement of blood within the
assessed arteries, and disappearance of
systolic flow on subsequent testing when
previously documented as present
• TCD is not considered an accurate and reliable
ancillary test in the confirmation of brain
39. • Advantages
– Easily accessible, portable
– Relatively inexpensive
– No contrast agents
• Disadvantages
– Lack of validation. Many false positives and
negatives
– 20%- thick cranium
• Used as a screening tool
40. Brain Death Controversy
• Controversial
• ?non acceptance of brain death as death.
• The idea that irreversible loss of brain function is
a sufficient condition for the certification of
death?
• Ariel Sharon? 8 years- vegetative state.
– fMRI – response to stimuli from family?
• Jahi McMath?
41.
42. One case study of reversible brain
death.
• One case study
• “reversible brain death after cardiopulmonary
arrest and induced hypothermia”
• Webb Adam C. MD, Samuels, OwenB MD
• Critical care Medicine June 2011 Vol 39- issue
6 pp 1538-1542
• ICU of an academic tertiary care hospital
43. Reversible brain death?
• 55 yo M
• This patient had a PEA arrest from asthma with time to ROSC of 20mins.
His sats were 60% even before the arrest.
• Cardiac arrest preceded by respiratory arrest.
• Therapeutic hypothermia for neuroprotection. ?not indication to be
cooled
• After rewarming to 36’5, sluggishly reactive pupils, spontaneous
myoclonic movements, absent corneal reflexes, and intact gag and
spontaneous respirations.
• Over 24 hours, remaining cranial nn function was lost. Clinical examination
consistent with brain death. Apnea test and repeat clinical examination
after 6 hours confirms brain death.
• Family consented for organ donation
• 24 hours after brain death pronouncement, in OT, patient regained corneal
and cough reflex, and spontaneous respirations.
44. DBD,DNDD
• Problems with terminology. “brain death”, “cardiac
death” and “circulatory death” is that they are
inaccurate and potentially misleading.
• “Donation after Neurological Determination of Death”
DNDD
45. • Failure to distinguish between patients who
are “dead,” “brain-dead,” “in a chronic
vegetative state,” “minimally conscious,”
“comatose,” or “terminally ill but conscious” is
a source of endless confusion.
46. 1. Apart from identifying evidence of sufficient intracranial pathology, list the
preconditions that must be met prior to the determination of brain death by
clinical criteria.
Minimum period of 4 hours in which the patient is observed to have
unresponsive coma, unreactive pupils, absent cough/tracheal reflex and no
spontaneous respiratory effort
• Normothermia (temp >35oC)
• Normotension (SBP >90 mmHg, MAP >60 mmHg in adult)
• Exclusion of sedative drugs
• Absence of severe electrolyte, metabolic or endocrine disturbance
• Intact neuromuscular function
• Ability to examine the brainstem reflexes including at least one ear and
one eye
• Ability to perform apnoea testing
2. What is the recommended minimum time for observation in cases of
hypoxic- ischaemic brain injury, prior to performing clinical testing of brain-
stem function?
24hours
Answers to CICM exam question
47. 3. For each of the following brainstem reflexes, list the
cranial nerves that are tested
a. Cough reflex - cranial nerve X
b. Vestibulo-ocular reflex - cranial nerve III,IV,VI,VIII
c. Pupilary light reflex - cranial nerve II & III
d. Corneal reflex - cranial nerve V & VII
e. Gag reflex - cranial nerve IX & X
(for each part of this question ALL cranial nerves are
required in order to receive the 5 marks, no marks should
be given for an incomplete response)
48. 4. List three contraindications to performing apnoea testing
a. Concomitant high cervical cord injury
b. Severe hypoxaemia
c. Haemodynamic instability
5. List the acceptable imaging techniques that may be used to
demonstrate brain death as an alternative to clinical testing as
recommended by the ANZICS Statement on Death and Organ
Donation
• Four vessel intra-arterial catheter angiography with digital
subtraction (preferred)
• Radionuclide imaging with Tc-99mHMPAO and single
photon emission computerised tomography (SPECT)
(preferred)
• CT angiography (limited experience to date) (acceptable)
Notas do Editor
Determination of brain death requires that there is unresponsive coma, the absence of brain-stem reflexes and the absence of respiratory centre function, in the clinical setting in which these findings are irreversible.
In particular, there must be definite clinical or neuro-imaging evidence of acute brain pathology (e.g. traumatic brain injury, intracranial haemorrhage, hypoxic encephalopathy) consistent with the irreversible loss of neurological function.
(This contrasts with the UK where brain stem death even in the presence of cerebral blood flow is the standard.)
There must be a minimum of 4 hours observation and mechanical ventilation during which the patient has unresponsive coma GCS 3, prior to undertaking the first set of brain death tests.
Return of brain function may be delayed for more than 4 hours after resuscitation from cardiorespiratory arrest. It is therefore recommended that in cases of acute hypoxic ischaemic brain injury, clinical testing for brain death be delayed for at least 24 hours subsequent to the restoration of spontaneous circulation. Brain death may be determined prior to 24 hours by demonstration of absent cerebral blood flow.
Therapeutic hypothermia may modify outcome prediction after cardiac arrest and there are published case reports suggesting that determination of brain death might be confounded either by hypothermia itself or impaired clearance of associated medications.
It is therefore recommended when induced hypothermia has been used after resuscitation from cardiorespiratory arrest that clinical testing for brain death be delated for at least 24 hours AFTER rewarming. Brain death may be determined prior to 24 hours by demonstration of absent cerebral blood flow.
Summary:
Absence of responsiveness
Absence of brain death reflexes
Apnoea
Spinal reflexes can either be spontaneous or elicited by stimulation
Spinal reflexes may include:
Extensor pronation movements of the upper limbs or non speicif flexion of the lower limbs
Undulating toe reflex- plantar flexion of great toe, followed by brief plantar flexion sequentionally of 2nd to 5th toes
Lazarus sign (bilateral arm flexion, shoulder adduction, hand raisingabove the vest, and may include flexion of trunk hips and knees
Deep tendon reflexes
Plantarresponses either flexor or extensor
Respiratory-like movements (shoulder elevation and adduction back arching or intercostal expansion) without significant tidal volume, and head turning
Sweating blushing tachycardia
Normal BP without the need for pharmacological support
Absence of DI
Inspect EAC with otoscope. If not visible, canal must be cleared before testing can be done.
Elevate head 30 degrees to place the horizontal semicircular canal in a horizontal position.
50mls of ice cold water into ear canal. Hold eyelids and observe eye movement for 60 secs
Stimulate the posterior pharyngeal wall
? If orally intubated
Stimulate the tracheo bronchial wall with a soft suction catheter
To demonstrate the lack of ventilatory drive.
Usually PCO2 rises by 3 mmHg for every minute of apnoea. As PaCO2 rises, the vent centre is maximally stimulated by a PaCo2 of 60mmHg (from normocapnea ~usually about 10 minutes)
Preoxygenate 100% for 5 min
Issues with delayed filling of major vessels can occur
(1) 4 vessel angiogram (no flow above the carotid siphon in anterior circulation and foramen magnum in posterior circulation) Adv: Gold standard Disadv: expensive/Invasive – exposes potential organ donors to toxic contrast material.
(2) Tc-99 HMPAO SPECT radionuclide imaging (lack of perfusion across the BBB to be retained by the brain parenchyma) Advantage-ability to detect blood flow in patients who have coma secondary to drug intoxication. Disadvantage- posterior fossa circulation not evaluated.
(3) CT angiography (less experience with this technique, absent enhancement at 60 seconds in different cerebral arterial distributions, presence of contrast in external carotid artery must occur to establish a technically adequate study)
transcranial doppler (TCD) may be used as a screening test optimise the timing of the contrast study (TCD can rule out brain death, but cannot confirm it)
Cerebral Perfusion Scintigraphy – advantage – able to show the posterior fossa, Disadvantage – cost
XeCT- adv: High spatial resolution, eliminates issues with contrast mediated tissue injury. Disav: Neuroradiology expertise required, difficult accessibility.
MRAngiography, MR perfusion
Four-vessel cerebral angiography is the standard of confirmatory tests.
The currently accepted method of assessment is done with separate contrast injections performed in both common or internal carotid arteries, as well as in both vertebral arteries.
Blood flow should not be demonstrated above the level of the carotid siphon in the anterior circulation or above the foramen magnum in the posterior circulation.
Although no false positive cases have been reported, false negative examinations may occur if cerebral angiography is performed on a patient in whom there is no significant elevation of the ICP, or if angiography is performed in a manner where contrast is injected too vigorously into the downstream circulation, thereby artifactually opacifying the intracranial vasculature. (?screen with TCD)
Arrow points to absence of posterior fossa circulation. Tracer is seen in the carotid arteries to indicate that an adequate bolus is given. Because of the maintained external carotid artery perfusion, the nasal region can be quite prominent. This is referred to as the “hot nose” sign
. This means that in 100 cases of patients satisfying the clinical tests for death, the CTA test will correctly identify 85 of the cases.
The available evidence cannot support the use of CT angiography as a mandatory test, or as a complete replacement for neurological testing, in the management pathway of patients who are suspected to be clinically brain dead. CT angiography may be useful as a confirmatory or add-on test following a clinical diagnosis of death, assuming that clinicians are aware of the relatively low overall sensitivity.
http://www.cochrane.org/CD009694/ANAESTH_the-use-of-computed-tomography-angiography-cta-to-confirm-the-clinical-diagnosis-of-brain-death
. TCD has many potential advantages. It is safe, portable, noninvasive, and relatively rapidly performed. As well, it is relatively inexpensive, and does not require administration of potentially organotoxic contrast agents. However, TCD is not widely available, and is quite labour-intensive, requiring tremendous skill and rigor in its application to insonate all of the major intracranial arteries
In addition, up to 20% of patients may fail TCD scanning as their cranial vaults are too thick to allow appropriate visualization of these arteries. As well, many authors have reported false positives and negatives using TCD
Because of these drawbacks, as well as its lack of validation,
The Jahi McMath case centers on a teenaged girl who was declared brain dead in California following surgery in 2013, when she was 13, and the bioethical debate surrounding her family's rejection of the medicolegal findings of death in this case, and their efforts to maintain her body on mechanical ventilation and other measures, which her parents considered to constitute life support of their child but which her doctors considered to be futile treatment of a deceased person.[3][4][5][6][7][8] In October 2014, the McMath family attorney presented new evidence and made the unprecedented request that Jahi McMath's brain death declaration be overturned. The attorney later withdrew this request, saying he wanted time for the court-appointed medical expert and his own medical experts to confer.[9][10][11][12][13] In March 2015, McMath's family filed a malpractice lawsuit against Children's Hospital Oakland and against the surgeon who performed McMath's surgery indicating they were prepared to argue as part of the lawsuit that McMath is not dead.
Donation after Neurological determination of death