The Effect Of Intrathecal Blook On The Depth Of Anesthesia

Objective: To compare the effect of general anesthesia and combined epidural-general anesthesia on the depth of anesthesia. Methods: 42 ASA I - II patients undergoing elective thoracic surgery were divided into two groups using a prospective double-blind design: Group I, general anesthesia (n=21), group II, combined epidural-general anesthesia (n=21). Bispectral index (BIS) was continuously monitored in both groups during the surgery. All patients received epidural puncture and catheterizing. Patients in group I received epidural normal salt while the patients in group II received epidurally 0.25% bupivacaine. All the patients in both groups received same drug for anesthesia induction and the anesthesia was maintained with propofol and vecuronium infusion, fentanyl was injected intravenously as necessary. According to invasive blood pressure, the rate of propofol infusion was adjusted to keep homodynamic stable. Vecuronium infusion was stopped after thorax was closed and propofol infusion was stopped before skin was sutured. All patients were asked for awareness during the surgery in postoperative 24 hours.Results: (1) In both groups the BIS scores reduced after induction (P<0.05). There was no significant difference between the two groups (P>0.05). (2) Theaverage of the BIS scores during the surgery were lower in group I than in group II (P<0.05). The amount of propofol used significantly more in group I compared to that of group II (P<0.05). (3) The time of recovery, awakening and extubation was longer in group I than in group II (PO.05), but there was no significant difference in the BIS scores at the time of recovery, awakening and extubation between the two groups. (4) No single case of awareness during the surgery happened in postoperative 24 hours investigation.Conclusion: Compared with general anesthesia, combined epidural-general anesthesia reduced the dosages of anesthetics without increasing of awareness during the surgery. Combined epidural-general anesthesia also made the patients recovery from the anesthesia more quickly.