COMPARISON BETWEEN CONTINUOUS BRAIN-TISSUE PO(2), PCO(2), PH, AND TEMPERATURE AND SIMULTANEOUS CEREBROVENOUS MEASUREMENT USING A MULTISENSOR PROBE IN A PORCINE INTRACRANIAL-PRESSURE MODEL

Local brain tissue oxygenation (p(ti)O(2)) and global cerebrovenous he moglobin saturation (SjO2) are increasingly used to continuously monit or patients after severe head injury (SHI). In patients, simultaneous local and global oxygen measurements of these types have shown differe nt results regarding the comparability of the findings during changes in CPP and ICP. This is in contrast to theoretical expectations. The a im of this study was to compare p(ti)O(2) measurement with cerebroveno us oxygen partial pressure measurement (p(cv)O(2)) in an animal intrac ranial pressure model. To this end, a multisensor probe was placed in the left frontoparietal white matter to measure p(ti)O(2), pCO(2) (p(t i)CO(2)), pH (pH(ti)), and temperature (t(ti)) while simultaneously me asuring these same parameters (pc(vb)O(2), p(cv)CO(2), pH(cv), t(cv)) in the sagittal sinus of 9 pigs under general anesthesia. By stepwise inflating a balloon catheter, placed in supracerebellar infratentorial compartment, ICP was increased and CPP was decreased. The baseline le vels of p(ti)O(2), p(ti)CO(2), and pH(ti) in the noninjured brain tiss ue showed more heterogeneity compared to the findings in cerebrovenous blood. Both, p(ti)O(2) and p(cv)O(2) were significantly correlated to the induced CPP decrease. PCO2 was inversely correlated to the course of CPP in both measurement compartments. Temperature measurement show ed a positive correlation with CPP in both compartments. These finding s demonstrate that brain tissue oximetry and cerebrovenous pO(2) measu rement are sensitive to CPP changes. The newly available continuous pa rameters in multisensor probes could be helpful in interpreting findin gs of cerebral oxygen measurement in man by analyzing the interrelatio nship of these parameters.