Correlations between the quantity of cerebral flow, brain surface pO2, and EEG in the dog

Complete cerebral ischemia was carried out in 19 dogs by repeated occlusion of the large neck arteries. The interruption of cerebral blood flow (CBF) was controlled with the electric silence recorded on EEG and the rapid fall of brain surface oxygen tension (bspO2). A critical flow was determined in each experiment by release of clamping of one artery (left carotid artery), which seemed effective not only to stop the decrease of bspO2 but also to ensure the reappearance of EEG waves. This crucial value of carotid artery flow (CAF) was 49 ml/min and 38 ml/min after the first and second occlusions, respectively. The EEG changes during different phases of experiments were stored on magnetic tape and analyzed by computer. The distribution of the analyzed power spectrum of EEG provides a special characterization of brain function. Strict correlations are found between the actual blood flow and the changes of EEG and bspO2. Either alteration of the recorded two parameters can accurately reflect the possibility of brain recovery during and after short-lasting ischemia.