Effects of increasing concentrations of propofol on jugular venous bulb oxygen saturation in neurosurgical patients under normothermic and mildly hypothermic conditions

Background: Recent evidence suggested that propofol can deteriorate the cerebral oxygen balance compared with inhalational anesthetics. However, dose-related influences of propofol on cerebral oxygen balances were not clearly investigated. In the current study, the authors investigated the effects of increasing concentrations of propofol on jugular venous bulb oxygen saturation (Sjo.) in neurosurgical patients under normothermic and mildly hypothermic conditions. Methods: After institutional approval and informed consent were obtained, 30 adult patients undergoing elective craniotomy were studied. Patients were randomly allocated to either normothermic or hypothermic group (n = 15 in each group). in the normothermic and hypothermic groups, tympanic membrane temperature was maintained at 36.5 degrees and 34.5 degrees C, respectively. Sjo, was measured at predicted propofol concentrations of 3, 5, and 7 mu g/nd using a target-controlled infusion system in both groups. Results: At a predicted propofol concentration of 3 mu g/ml, there were no significant differences in Sjo, values between the normothermic and hypothermic groups, although the incidence of desaturation (Sjo(2) < 50%) was significantly higher in the normothermic group than in the hypothermic group (30% vs. 13%; P < 0.05). Sjo(2) values and the incidence of desaturation remained unchanged during the changes in predicted propofol concentration from 3 to 7 mu g/ml both in the normothermic and hypothermic groups. Conclusion: The results indicated that the increasing concentrations of propofol did not affect Sjo, values in neurosurgical patients under normothermic and mildly hypothermic conditions.