Brain Death

Key Features

• Complete and irreversible cessation of all brain function

• Cause of coma must be established, compatible with a known cause of brain death

• Reversible coma simulating brain death may be seen with

  • Hypothermia (temperature < 32 °C)

  • Overdosage with central nervous system depressant drugs

• Hypothermia and drug overdose must be excluded by warming the patient and allowing enough time for all sedating medications to be metabolized (ie, at least 5 half-lives) or by measuring serum levels

• Severe blood pressure, electrolyte, acid-base, and endocrine derangements cannot be present

Clinical Findings

• Coma (irreversible)

• No response to external stimulation

• No brainstem reflexes

• No spontaneous respirations and no respirations during apnea test

Diagnosis

• The apnea test (presence or absence of spontaneous respiratory activity at a PaCO₂ of at least 60 mm Hg or after a rise of 20 mm Hg from baseline) serves to determine whether the patient is capable of respiratory activity

• An isoelectric electroencephalogram recorded according to the recommendations of the American Electroencephalographic Society may help in confirming the diagnosis

• Alternatively, the demonstration of an absent cerebral circulation by intravenous radioisotope cerebral angiography or four-vessel contrast cerebral angiography is confirmatory

Treatment

• Palliative care