Jugular bulb oxygen saturation during propofol and isoflurane/nitrous oxide anesthesia in patients undergoing brain tumor surgery

Abstract

We investigated, in brain tumor patients, the jugular bulb venous oxygen partial pressure (PjO2) and hemoglobin saturation (SjO2), the arterial to jugular bulb venous oxygen content difference (AJDO2), and middle cerebral artery blood flow velocity (Vmca) during anesthesia, and the effect of hyperventilation on these variables. Twenty patients were randomized to receive either isoflurane/ nitrous oxide/fentanyl (Group 1) or propofol/fentanyl (Group 2). At normoventilation (PacO2 35 +/- 2 mm Hg in Group 1 and 33 +/- 3 mm Hg in Group 2), SjO2 and PjO2 were significantly higher in Group 1 than in Group 2 (SjO2 60% +/- 6% and 49% +/- 13%, respectively; P = 0.019) (PjO2 32 +/- 3 and 27 +/- 5 mm Hg, respectively; P = 0.027). In Group 2, 5 of 10 patients had SjO2 < 50%, and 3 of these patients had SjO2 < 40% and AJDO2 > 9 mL/dL. All patients in Group 1 had SjO2 > 50%. During hyperventilation, there were no differences in SjO2, PjO2, or AJDO2 between the two groups. On hyperventilation, there was no correlation between the relative decreases of Vmca and 1/AJDO2 (r = 0.21, P = 0.41). The results indicate during propofol anesthesia, half of the brain tumor patients showed signs of cerebral hypoperfusion, but not during isoflurane/nitrous oxide anesthesia. Furthermore, during PacO2 manipulations, shifts in Vmca are inadequate to evaluate brian oxygen delivery in these patients.

Implications: During propofol anesthesia at normoventilation, 50% of brain tumor patients showed signs suggesting cerebral hypoperfusion, but this could not be demonstrated during isoflurane/nitrous oxide anesthesia. During PacO2 manipulations, consecutive measurements of the cerebral blood flow velocity may be inadequate to assess cerebral oxygenation.