Detection of brain death in barbiturate coma: the dilemma of an intracranial pulse

Patients treated with barbiturate coma for elevated intracranial pressure after head injury may suffer brain death. Since such patients have an iatrogenically induced absence of neurological function, brain death cannot be diagnosed clinically. Furthermore, as demonstrated by two of our patients, monitoring of intracranial pressure, even in the face of brain death, may show a low intracranial pressure and an intracranial pulse, suggesting the presence of adequate cerebral perfusion pressure and, therefore, brain viability. Under these circumstances, however, significant intracranial blood flow may be absent. Therefore, we suggest that a patient in barbiturate coma should undergo serial blood flow studies, even when the intracranial pressure is low and an intracranial pulse is present, to determine whether brain death has occurred.