verification of brain death in the ventilated patient

see also:

• death and the potentially dead
• how to verify death
• reportable and reviewable deaths - deaths which MUST be reported to the Coroner
• how to complete a death certificate for cause of death
• the comatose patient
• post-coma unresponsiveness (persistent vegetative state)

• while the definition of brain death is largely a matter of legal statute, the law does not specify a precise means for its assessment.
• two separate examinations should be performed by two medical practitioners and preferably, at least 2 hours apart, but there is no legal stated time the examinations be separated by, and there is no legal requirement for two medical practitioners if tissues or organs will not be removed for transplantation purposes.
• time of death for legal purposes is the time of the second examination
• the 1st formal examination should only be performed after:
  • all the pre-conditions have been met
  • a minimum of 4 hours observation and mechanical ventilation during which the patient was comatose (GCS 3), had non-reactive pupils, absent cough and gag reflex, and no spontaneous efforts of breathing.
    • NB. in cases of hypoxic brain injury or encephalitis, a longer period of observation may be required¹⁾

• diagnosis of severe brain injury and coma which is consistent with progression to brain death (usually confirmed with neuro-imaging)
• exclusion of coma caused by drugs or poisoning
  • most commonly used drugs will be cleared by 8-12 hours but some longer acting drugs such as barbiturates, benzodiazepines, etc will require longer to clear
  • consider blood and urine drug screens if substance abuse is suspected
• exclusion of metabolic causes (eg. severe electrolyte disturbances (esp. severe hypophosphataemia) or endocrine disturbances)
• exclusion of hypothermia (a core temperature of 35deg C should be achieved by active re-warming if necessary)
• confirmation of intact neuromuscular conduction
  • particularly if neuromuscular relaxants have been used

• response to painful stimuli applied in the cranial nerve distribution
• pupillary responses to light
• corneal reflexes
• gag reflex
• cough reflex
• vestibulo-ocular reflexes
• respiratory function testing if none of the above reflexes are present, and there is no severe hypoxic respiratory failure:
  • pre-oxygenate with 100% oxygen
  • cease mechanical ventilation
  • supply oxygen through a tracheal catheter or other device
  • apnoea with paCO2 > 60mmHg and pH < 7.30 confirms absence of spontaneous respiration

• spontaneous “spinal” movements of the limbs
• respiratory-like movements (eg. shoulder elevation and adduction, back arching, intercostal expansion) without significant tidal volume
• sweating, blushing, tachycardia
• normal blood pressure without pharmacologic support
• absence of diabetes insipidus (normal osmolar control mechanism)
• deep tendon reflexes
• Babinski's reflex

• radiocontrast cerebral angiography
• HM-POA raduo-nuclide scanning
• EEG
  • NB. presence of electrical activity on an EEG does not necessarily indicate viable functioning neuronal activity - electrical interferences from ICU equipment, etc may be the cause
  • a sophisticated analysis of the EEG using Power Spectrum Density and Permutation Entropy methods appears to discriminate brain death from coma with 90-93.5% ²⁾