CEREBRAL INTERSTITIAL-TISSUE OXYGEN-TENSION, PH, HCO3, CO2

BACKGROUND There are many techniques for monitoring the injured brain following trauma, subarachnoid hemorrhage, or surgery. It is thought t hat the major determinants for recovery of injured cerebral tissue are oxygen, glucose delivery, and the clearance of metabolites. These fac tors, at optimal levels, are probably responsible for the regaining of neuronal functions. These parameters are in turn dependent on the tis sue's blood flow and metabolism. METHODS We have been using a single, compact, polyethylene sensor, the Paratrend 7(TM), for the measurement of cerebral oxygen tension, CO2, pH, and temperature. This sensor is designed for continuous blood gas analysis to aid in monitoring neuros urgical patients, both during surgery and in the intensive care unit. RESULTS Using the Paratrend 7(TM) sensor, we found the normal range of values to be: PO2 33 +/- 11 mm Hg; PCO2 48 +/- 7 mm Hg; pH 7.19 +/- 0 .11. Critical measurements are considered to be tissue PO2 <10 mm Hg; PCO2 >60 mm Hg, and pH <6.8. We have had no complications with this de vice; the risks are similar to those of plating a parenchymal intracra nial pressure monitor. CONCLUSIONS We believe that assessment of inter stitial cerebral oxygen saturation can be of great value both intraope ratively and postoperatively. In our experience, the Paratrend 7(TM) s ystem is an effective method of measuring tissue cerebral oxygen tensi on, along with carbon dioxide levels, pH, and temperature. (C) 1997 by Elsevier Science Inc.