Hyperoxia of internal jugular venous blood in brain death.

Abstract

✓ The oxygen tension and acid-base values of internal jugular venous blood were compared to those of arterial and systemic mixed venous blood in 40 patients suffering from severe head injury. The results were divided into “brain death” and “coma groups” according to the clinical status when the sample was obtained. Hyperoxia of the jugular venous blood was a common finding in both groups, especially in the brain death group. The mean value of the arteriojugular venous oxygen content difference was 1.86 vol % in the brain death group, and 4.41 vol % in the coma group. Although most of the oxygen content differences in the brain death group were below 3 vol %, there was an overlap with the coma group at the low level of arteriojugular O2 difference. For definitive assessment of brain death, the fact that jugular pO2 was higher than that in systemic mixed venous pO2 was more valuable than the decrease of arteriojugular oxygen difference. The extreme hyperoxia of the jugular venous blood is possibly a sign of brain death, but should not be interpreted as the result of decreased oxygen consumption in the brain, because most of the jugular venous blood is returned from the extracerebral tissues. The causes of jugular hyperoxia in the state of brain death are discussed.