With respect to brain death and organ dbnation as specified in the ANZICS guidelines:
a) List the pre-conditions that would preclude the determination of brain death by clinical examination. (30% marks)
b) List the components of the clinical examination to determine brain death and where appropriate the cranial nerve(s) being tested. (40% marks)
c) If clinical testing has been precluded, what investigations can be used to demonstrate a lack of intracranial blood flow? (30% marks)
Conditions precluding clinical testing brain death
Clinical test Cranial Nerve
ii. Pupillary reflex II, III
iii. Corneal reflex V, VII
iv. Pain reflex in trigeminal nerve distribution V, VII
v. Vestibular ocular reflex III, IV, VI, VIII
vi. Gag reflex IX, X
vii. Cough reflex X
viii. Breathing effort with apnoea
Imaging techniques need to be done in association with exclusion of preconditions and assessment of those cranial nerves that can be assessed and results need to be reviewed by 2 appropriate clinicians excluding the clinician performing the test.
The below preconditions are taken directly from the ANZICS Statement.
Four hours of observation during which the patient remains in unresponsive coma
Preconditions for apnoea testing
Testing for unresponsive coma
Brain Stem Reflex Testing (these are tested in sequence; all reflexes must be absent)
Investigations used to demonstrate a lack of intracranial blood flow are slightly different to those which might be used to demonstrate brain death, as the lattercategory may include such things as EEG (isoelectric EEG).
The imaging modalities are discussed in greater detail in the chapter on radiological testing for brain death.
In brief, the ANZICS-recommended modalities are:
Modalities which are not recommended as strongly include:
The ANZICS statement now says CT angio "is acceptable", whereas at the time of this exam paper being written they merely weazeled that it "may be acceptable". The argument againt CT angiography is the gated timing of the scan. Whereas DSA watches contrast wash in over time in a series of still images, the CT offers a momentary snapshot of that contrast in the vessels. One might argue that the CT was mis-timed, and the contrast did not yet have time to move into the brain (in this way, perfectly healthy people could be made to appear brain-dead by adjusting the timing of the scan). Obviously, when one is going to declare brain death, there needs to be no argument about the validity of the confirmatory test. The 2014 Cochrane review (Taylor et al) could not support the use of CTA, but subsequent improvements in technology have improved the level of confidence with this modality. ANZICS now recommends the use of a four-point scale to radiologically confirm absent brain perfusion by CTA, which consists of "absent enhancement of both middle cerebral artery (MCA) cortical branches (i.e. beyond the Sylvian branches); andabsent enhancement of both internal cerebral veins"
Taylor, Tim, et al. "Computed tomography (CT) angiography for confirmation of the clinical diagnosis of brain death." The Cochrane Library (2014).