Prerequisites:
(1) The proximate cause of brain dysfunction is known and demonstrably irreversible.
(2) There is clinical and/or neuroimaging evidence of an acute CNS catastrophe compatible with brain death.
(3) There are no medical conditions that could interfere with the clinical assessment (severe electrolyte or acid-base abnormality, severe endocrine disturbance).
(4) There is no drug intoxication or poisoning.
(5) The core body temperature >= 32°C (>= 90°F).
Cardinal findings:
(1) apnea (see apnea test in previous section)
(2) coma or unresponsiveness (absence of motor response and grimacing) to pain (nail-bed pressure, supraorbital pressure, deep pressure on temporomandibular joint)
(3) absence of brain stem reflexes
Absent brain stem reflexes:
(1) no pupillary response to bright light; pupils should be 4 to 9 mm in diameter (midposition to dilated)
(2) no oculocephalic reflex (not performed if there is a fracture or instability of the cervical spine)
(3) no oculovestibular response to caloric stimulation with cold water
(4) no corneal reflex to touch
(5) no jaw reflex
(6) absent pharyngeal reflex (no response after stimulation of the posterior pharynx)
(7) no tracheal reflex (no cough response on tracheal suctioning)
Repeat testing is recommended to confirm the above findings. The usual interval for the adult is 6 hours, but this is arbitrary.
Confirmatory testing is not required. It is desirable when a specific component of the clinical assessment cannot be performed reliably. Methods include:
(1) angiography
(2) EEG
(3) transcranial Doppler ultrasonography
(4) technetium-99m hexamethylpropyleneamineoxime brain scan
