Outline the preconditions that must be met in order for accurate determination of brain death by clinical examination.
• Evidence of sufficient intracranial pathology or a known cause of coma e.g.; traumatic brain injury, intracerebral haemorrhage, hypoxic-ischaemic encephaloopathy
• normothermia (temperature > 35°C);
• normotension (as a guide, systolic blood pressure > 90 mmHg, mean arterial pressure (MAP> 60 mmHg in an adult);
• exclusion of effects of sedative drugs (self-administered or otherwise) — the time taken for plasma concentrations of sedative drugs to fall below levels with clinically significant effects depends on the dose and pharmacokinetics of drugs used, and on hepatic and renal function. If there is any doubt about the persisting effects of opioids or benzodiazepines, an appropriate drug antagonist should be administered;
• absence of severe electrolyte, metabolic or endocrine disturbances— these include: marked derangements in plasma concentrations of glucose, sodium, phosphate or magnesium; liver and renal dysfunction; and severe endocrine dysfunction;
• intact neuromuscular function— if neuromuscular-blocking drugs have been administered, a peripheral nerve stimulator or other recognised method (e.g. electromyography) should always be used to confirm that neuromuscular conduction is normal;
• ability to adequately examine the brain-stem reflexes— it must be possible to examine at least one ear and one eye; and
• ability to perform apnoea testing— this may be precluded by severe hypoxic respiratory failure or a high cervical spinal cord injury.
The answer above is lifted straight from the ANZICS Statement on Death and Organ Donation (I have linked to Version 3.2, from 2013).
In brief, the preconditions are:
- Pathology sufficient to explain brain death
- Exclusion of the effects of sedating drugs
- Absence of severe electrolyte, metabolic or endocrine disturbance:
- Glucose <3 or > 25 mmol/L
- Sodium <125 or >160 mmol/L
- phosphate <0.5 mmol/L
- magnesium <0.5 mmol/L
- urea > 40 mmol/L
- "untreated severe hypothyroidism or severe hypoadrenalism"
- Intact neuromuscular function
- Ability to adequately examine brainstem reflexes
- Ability to perform apnoea testing
ANZICS Death and Organ Donation Committee, THE ANZICS STATEMENT ON DEATH AND ORGAN DONATION Edition 3.2 2013