Alterations in Cerebrospinal Fluid PO2, PCO2, and pH Measurements during and after Experimental Thoracic Aortic Cross-Clamping

In a model of aortic cross-clamping, we studied the use of a multiparameter sensor for measurement of cerebrospinal fluid (CSF) PO2, PCO2, and pH during and after aortic cross-clamping. The present study addressed the above-mentioned alterations and their relation according to time intervals. In 31 pigs, a sensor was introduced into the intrathecal space and epidural laser Doppler was used to measure spinal cord blood flow (SCF). By placing the aortic clamp at different levels, three different spinal cord ischemia groups were obtained (mild, moderate, and severe). CSF variables with SCF were studied for 25%, 50%, and 100% changes according to baseline level. In the clamping period, SCF decreased 71.5%, 40.0%, and 33.3% in groups 1, 2, and 3, respectively. CSF O2 tension reached 0 in group 1, decreased 74.8% in group 2, and was 12.7% in group 3. CSF CO2 tension increased 247.2% and 202.0% in groups 1 and 2, respectively, but slightly increased in group 3. The maximum reaction time of CSF O2 tension was about 16.7-26.9 min, although this range was 34.5-49.8 min in CSF CO2 tension. We recognized that O2 tension reacts faster than PCO2 and pH. It is possible for O2 tension to be used faster than produced CO2 in the ischemic medium, although it is known that the diffusion rate of CO2 is much higher. Spinal cord O2 tension monitoring is an important method to detect ischemic changes.