The changes in brain surface, intracerebral tissue, and transconjunctival oxygen tension during hypo- and hyperventilation.

To evaluate the validity of organ surface oxygen tension monitoring for assessment of cerebral perfusion, the oxygen tension in brain surface (Pbs(O)(2)), intracerebral tissue (Pic(O)(2)), and conjunctiva (Pcj(O)(2)) were measured simultaneously during hypo- and hyperventilation in dogs, and the comparative study was done. Pbs(O)(2) and Pic(O)(2) significantly increased during hypoventilation and decreased during hyperventilation. And the values of Pbs(O)(2) and Pic(O)(2) were correlated to the corresponding Pa(CO)(2) values significantly ( P << 0.001 in each case). On the contrary, Pcj(O)(2) did not change significantly during hypo- and hyperventilation. These findings indicate that Pbs(O)(2) as well as Pic(O)(2) could reflect the changes in cerebral perfusion caused by induced hyper- and hypocapnia but that Pcj(O)(2) could not.