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 that the major determinants for recovery of injured cerebral tissue are oxygen, glucose delivery, and the clearance of metabolites. These factors, at optimal levels, are probably responsible for the regaining of neuronal functions. These parameters are in turn dependent on the tissue's blood flow and metabolism.


METHODS
We have been using a single, compact, polyethylene sensor, the Paratrend 7 for the measurement of cerebral oxygen tension, CO2, pH, and temperature. This sensor is designed for continuous blood gas analysis to aid in monitoring neurosurgical patients, both during surgery and in the intensive care unit.


RESULTS
Using the Paratrend 7 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 device; the risks are similar to those of placing a parenchymal intracranial pressure monitor.


CONCLUSIONS
We believe that assessment of interstitial cerebral oxygen saturation can be of great value both intraoperatively and postoperatively. In our experience, the Paratrend 7 system is an effective method of measuring tissue cerebral oxygen tension, along with carbon dioxide levels, pH, and temperature.
Charbel
F T
FT
Department of Neurosurgery, University of Illinois at Chicago 60612-7329, USA
Hoffman
W E
WE
Misra
M
M
Hannigan
K
K
Ausman
J I
JI
D001639:Bicarbonates / Q000378:metabolism*; D001921:Brain / Q000098:blood supply / Q000378:metabolism*; D002245:Carbon Dioxide / Q000378:metabolism*; D004867:Equipment Design; D006801:Humans; D006863:Hydrogen-Ion Concentration; D010100:Oxygen / Q000378:metabolism*; D013997:Time Factors
D001639:Bicarbonates; D002245:Carbon Dioxide; D010100:Oxygen