Brain Tissue Oxygenation in Brain Death

Abstract

The value of brain tissue oxygenation (PbtO2) measurements in determining brain death is unknown. Eleven of 72 patients who had brain tissue oxygen monitors placed experienced brain death. Admission diagnoses included six severe traumatic brain injuries, one multiple trauma with cardiac arrest, one brain tumor, one subarachnoid hemorrhage, one intracerebral hemorrhage, and one cerebral stroke. Eleven males and zero females were studied, with an average age of 26 years (range: 20-70 years). Nine patients had Glasgow Coma Scores (GCS) of 3 on admission, one patient had a GCS of 5, and one patient had a GCS of 15. Time from admission to declaration of brain death varied from 5 hours to 7 days; the most common interval was 1 or 2 days. Cerebral perfusion pressure (CPP) fell to 0 in eight patients, which indicated primary failure of cerebral perfusion. CPP stayed above 60 mmHg in three patients, indicating primary tissue failure, possibly of the cerebral microvasculature. PbtO2 fell to 0 in all patients who experienced brain death, and all patients with PbtO2 of 0 experienced brain death. None of the 61 patients who did not experience brain death had confirmed PbtO2 readings of 0. PbtO2 can be successfully and accurately used as a bedside adjunctive test for brain death. The use of PbtO2 as a sole confirmatory test for brain death in the setting of an appropriate clinical examination will require the evaluation of a larger number of patients to assess its sensitivity and specificity.