Effects Of Bispectral Index Monnitoring On The Time Of Extubation And Stress Response During Recovery Period In Patient Undergoing TIVA

Objective The purpose of this study was to determine whether maintaining relatively high BIS of 60-70 and enough analgesia would affect the recovery parameters such as time of emergence from anesthesia and extubation in patients undergoing total intravenous infusion anesthesia(TIVA) .The level of plasma Cortisol and glucagons was also investigated to estimate the stress response during the recovery period.Methods 30 ASA Ⅰ-Ⅱ patients aged 30-50 yr (17 male, 13 female) undergoing elective abdominal surgery were randomly allocated to one of the three groups of 10 each: manually controlled infusion(MCI) group, target controlled infusion(TCI )group and BIS monitoring group. All the patients urderwent TIVA. In MCI group.propofol was manually infused by 4-8mg/kg/h and dosage of fentanyl was controlled all by clinical practice.In TCI and BIS group ,the target concentration of propofol was set at 3 ug/ml at the beginning, and was adjusted against clinical signs as BP,HR and movement in TCI group. Near the end of operation, the target concentration was adjusted to make the awake time expressed on the TCI pump equally to the predicted time. Fentanyl was no longer used during the last 30min of the operation in MCI and TCI group ;In BIS group, the target concentration was adjusted according to the BIS values. BIS values was maintained at 45-55 during the majority of the opereation process whereas 60-70 near the end of the operation, 1ug/kg Fentanyl was given according to hemodynamic changes or movements. The time from the end of the operation to the endpoint of emergence(open the eyes in response to verbal command) ,extubation and orientation regaining was recorded. Each of 4ml vein blood sample was drawn at the three endpoint of pre-induction, just before and 3 min after extubation to measure the level of plasma Cortisol and glucagon.Results ① The time from the end of the operation to the endpoint of emergence, extubation and orientation regaining were shortest in BIS monitoring group (P< 0. 05 ). ②Changes of BP and HR in BIS monitoring group were not as severe as in the other two groups during recovery period. (P< 0.05) .③ The level of plasma Cortisol and glucagons were lowest in BIS group at the endpoints of emergence and extubation when compared with the other two groups,and were approximately equall to that of pre-induction. ④ There was no correlation between the awake time expressed on the TCI pump and the real emergence time (r=0.056, P>0.05) ⑤. The average normalized propofol infusion was( 4.96±1.02)mg/kg/h in BIS monitoring group, much lower than in MCI and TCI group. None of the patients reported awareness during a standardized interview.Conclusions Maintaining BIS values at 60-70 according to BIS mornitoring and adequate analgesia during emergence period allows faster recovery from anesthesia and lower propofol consumption without disturbing the stress response in patients undergoing TIVA.