Question 17

Created on Wed, 05/13/2015 - 00:45
Last updated on Thu, 01/14/2016 - 18:02
Pass rate: 84%
Highest mark: 9.1

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With regards to the determination of brain death:

a) 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:

b)What is the recommended minimum time for observation in cases of hypoxic-ischaemic brain injury, prior to performing clinical testing of brain-stem function?

c)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

d) List three contraindications to performing apnoea testing:

e) 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.

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College Answer

a)

  • 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

b)

24 hours

c)

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)

d)

      • Concomitant high cervical cord injury
      • Severe hypoxaemia
      • Haemodynamic instability

e)

  • Four vessel intra-arterial catheter angiography with digital subtraction (preferred)
  • Radionuclide imaging with Tc-99m HMPAO and single photon emission computerised tomography (SPECT) (preferred)
  • CT angiography (limited experience to date) (acceptable)

Discussion

This question tests the candidate's detailed knowledge of the ANZICS Statement on Death and Organ Donation (I have linked to Version 3.2, from 2013).

a) 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:

The below answer is taken directly from the Statement.

  • Normothermia
  • Normotension
  • Exclusion of the effects of sedating drugs
  • Absence of severe electrolyte, metabolic or endocrine disturbance
  • Intact neuromuscular function
  • Ability to adequately examine brainstem reflexes
  • Ability to perform apnoea testing

b)What is the recommended minimum time for observation in cases of hypoxic-ischaemic brain injury, prior to performing clinical testing of brain-stem function?

Again, quoting ANZICS:

"There must be a minimum of four hours observation and mechanical ventilation during which the patient has unresponsive coma "

c)For each of the following brainstem reflexes, list the cranial nerves that are tested:

a.

Cough reflex

Vagus (CN X)

b.

Vestibulo-ocular reflex

CN III, IV, VI, and VIII

c.

Pupilary light reflex

CN II, CN III

d.

Corneal reflex

CN V, CN VII

e.

Gag reflex

CN IX, CN X

In this list the college have omitted the test for pain in the trigeminal nerve distribution (CN V and VII)

d) List three contraindications to performing apnoea testing:

  • Hemodynamic instability
  • Severe hypoxic respiratory failure
  • High cervical cord injury

The presence of any brainstem reflexes is also a contraindication. Apnoea testing must be carried out only after the brainstem reflexes have been tested, and if any of them were found to be positive any further braindeath testing cannot continue.

e) 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 digital subtraction arterial angiography
  • Tc-99m HMPAO (technetium 99m radiolabelled hexamethyl propylene amine oxime) SPECT
  • CT angiography

References

ANZICS Death and Organ Donation Committee, THE ANZICS STATEMENT ON DEATH AND ORGAN DONATION Edition 3.2 2013