Evaluation of brain tissue O2 supply based on results of PO2 measurements with needle and surface microelectrodes.

Tissue PO2 distribution was measured in rat cerebral cortex during arterial normoxia and arterial hypoxia. The study was designed to examine the relationship between the PO2 histograms determined with surface electrodes in the superficial cortical cells and with needle electrodes in the cortical laminae below. Under normoxic as well as under hypoxic conditions the PO2 distributions of the compared brain regions were in close agreement. The results indicate that PO2 measurements in the brain cortex with surface microelectrodes give a correct view over the tissue oxygenation in cortical regions up to 500 microns below the measuring field.