Stability of oxygen transmissibility during ischemia

Simultaneous measurements of oxygen availability (O2a) and partial pressure (PO2) were made by the double noble metal electrode system designed by Erdmann and Krell in an attempt to monitor the oxygen transmissibility (Dk) with respect to time before and after ischemic episodes in the brain cortex. Available current equations can appropriately describe the performance of the electrode in a homogeneous nonconsuming medium, and with some experimental error this electrode system can be used to estimate oxygen transmissibility changes in the brain based on the different characteristics of the O2a (rod-type, flush-ended bare tip) and the PO2 (rod-type, recessed tip) cathodes. Our method monitors the oxygen transmissibility within the diffusion sphere of the bare tip as the ratio of the currents related to O2a and PO2. We find with this system that even prolonged global cerebral ischemia does not alter the oxygen transmissibility of the brain tissue. Therefore, alternation of the oxygen transmissibility can not be a contributing factor to postischemic cerebral malfunction.