Brain Tissue PO2: Correlation with Cerebral Blood Flow

This investigation analyzed 22 xenon CT cerebral blood flow (CBF) studies from 18 severely head-injured patients (Glasgow motor score < 6) who underwent xenon CT scanning while brain tissue oxygen tension (PbtO2) was being monitored. CBF was determined both in a localized region of interest around the actual or estimated location of the tip of the PbtO2 probe and in the entire corresponding CT slice. Linear regression analysis was used to examine the relationship between these CBF measurements and PbtO2 values recorded immediately prior to the xenon CT CBF study. PbtO2 varied linearly with both regional CBF (rCBF) and global CBF measurements, but the average global CBF value was significantly higher than the average rCBF value. Very low values were significantly less common for global CBF than for rCBF. Further investigation is necessary to determine how probe placement near contused areas vs. in normal tissue affects our understanding of the relationship between rCBF, global CBF, PbtO2, and cerebral oxygen consumption.