Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT Part 24-16: Stupor & Coma + Key Features Download Section PDF Listen +++ ++ 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 Download Section PDF Listen +++ ++ Coma (irreversible) No response to external stimulation No brainstem reflexes No spontaneous respirations and no respirations during apnea test + Diagnosis Download Section PDF Listen +++ ++ 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 Download Section PDF Listen +++ ++ Palliative care