You have taken over the care of a 22-year-old male admitted to ICU 3 days previously. He has sustained a severe isolated traumatic brain injury, including significant bilateral ocular injuries resulting in a ruptured globe on the right and traumatic third nerve palsy on the left.
Your colleagues report that the patient has stopped triggering the ventilator overnight and suspect that he might be brain dead.
Describe how you would diagnose brain death in this patient, including the options that are available
Ensure severity of brain injury is compatible with brain death (i.e. sufficient intracranial pathology) by reviewing relevant imaging.
Confirm that there has been a minimum of four hours observation and mechanical ventilation during which the patient has had unresponsive coma (GCS-3), no spontaneous breathing effort, absent cough/tracheal reflex.
Complete brainstem reflexes cannot be performed in this case and therefore brain death cannot be certified by clinical testing alone and will have to be determined by demonstrating absence of intracranial blood flow. However, the part of the clinical examination that can be undertaken should be performed.
Ensure that the following pre-conditions have been met in order to do limited brain death testing-
Normothermia (temperature > 35C);
Normotension (as a guide, systolic blood pressure > 90 mmHg, mean arterial pressure (MAP) > 60 mmHg in an adult);
Exclusion of effects of sedative drugs
Absence of severe electrolyte, metabolic or endocrine disturbances
Intact neuromuscular function
Ability to perform apnoea testing
Undertake the clinical tests that can be done
Response to painful stimulus to four limbs and trunk.
Response to pain in trigeminal nerve distribution
Gag reflex
Cough reflex
Apnoea testing
* Pupillary, corneal and cold caloric reflexes cannot be tested.
If all above reflexes absent, proceed to 4-vessel intra-arterial catheter angiography. Blood flow should not be demonstrable above the level of the carotid siphon in the anterior circulation, or above the foramen magnum in the posterior circulation
Alternatives-
Radionuclide imaging with Technetium -99m radiolabelled hexamethyl propylene amine oxime. (Tc-99mHMPAO)
Contrast CT or CT-angiography subject to specific radiologic diagnostic guidelines. (Absent enhancement bilaterally of all of the following are likely to be the most reliable early CT indicators of brain death: middle cerebral artery cortical branches — that is beyond the Sylvian branches; P2 segment of the posterior cerebral arteries; pericallosal arteries; and internal cerebral veins)
Brain death can then be certified by 2 medical practitioners (not including the practitioner who performed the imaging investigation) who have examined the patient and have knowledge of the circumstances of the coma
Important points in the answer:
Confirmation of a diagnosis compatible with brain death
Why clinical testing will not be sufficient
Preconditions satisfied
List of clinical tests that can be performed
Details of imaging test of choice + list of 2 alternatives
Detailed radiologic features required for diagnosis on contrast CT was not required, but an indication that specific radiologic criteria exist was expected.
Confirmation with clinical testing alone was considered a fatal error.
The diagnosis of brain death should be the bread and butter of an ICU specialist (as it is the thing that we do which is sufficiently unique to be the domain of intensivists alone). It is therefore surprising that only 43% of the candidates scored a passing mark. The college answer is remarkable in that it offers us a glimpse of the normally hidden marking rubric for an SAQ.
To break down this rubric into answerable components:
Confirmation of a diagnosis compatible with brain death
Why clinical testing will not be sufficient
Preconditions satisfied
List of clinical tests that can be performed
One needs to be reminded that the ANZICS statement recommends clinical testing should still be attempted: "If a complete examination is not possible (e.g. eye or ear trauma) or apnoea testing precluded (e.g. severe lung injury or high cervical trauma), then that part of the clinical examination that can be performed, should be undertaken".
Details of imaging test of choice + list of 2 alternatives