Conditions That May Cause Difficulty in Making the Diagnosis of Brain Death

Certain conditions and drugs may interfere with the making of a diagnosis of brain death in a patient.

Condition	Can Result In
anoxia	isolectric EEG
anticholinergic drugs	fixed pupils
encephalitis	isolectric EEG
hypothermia	isolectric EEG
"locked in" state	absent motor activity
neuromuscular blockers	fixed pupils, absent spontaneous respirations, absent motor activity
ototoxic drugs	absent oculovestibular reflex
posthyperventilation apnea	absent spontaneous respirations
pre-existing eye disease	fixed pupils
pre-existing middle ear disease	absent oculovestibular reflex
sedative-hypnotic agents	isolectric EEG, absent motor activity
traumatic head injury	isolectric EEG
vestibular suppressants	absent oculovestibular reflex
severe facial trauma	make testing brainstem reflexes difficult
sleep apnea or severe COPD	chronic retention to carbon dioxide, making the apnea test more difficult to interpret

A confirmatory test (such as measurement of cerebral perfusion) may be warranted if one or more of these conditions are present.

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