Monitoring brain PO2, PCO2, and pH during graded levels of hypoxemia in rabbits

Brain ischemia and hypoxia are of concern when they occur following traumat ic brain injury because they frequently result in potentially preventable s econdary brain damage. In this study, we examined the ability of an implant able catheter (Paratrend 7; Diametrics Medical, St. Paul, MN) to continuous ly measure brain tissue pH, PCO2, and PO2 during graded levers of hypoxia. Values obtained from this catheter were compared with simultaneous measurem ents of arterial and sagittal sinus blood. As expected, there was a good co rrelation between the changes in pH, PCO2, and PO2 in brain tissue and sagi ttal sinus blood. Brain tissue PO2 was numerically lower than sagittal sinu s blood at all inspired levels of oxygen. These data suggest that the Parat rend 7 may be useful in monitoring brain tissue oxygen tension in patients at risk for regional cerebral ischemia and hypoxia.