Clinical Research On Proper Concentration Of Sevoflurane In The General Anesthesia Induction

Objective: With index of BIS 60 ,the median effective dose (ED₅₀) is observed during the induction of general anesthesia with sevoflurane or together with implementation of midazolam, to provide some information for clinical anesthesia.Methods: we randomly selected 59 patients, ASAâ… -â…¡, receiving general anesthesia. Groupâ… (sevoflurane group) induced with sevoflurane administered by up-and-down method. After given midazolam 0.05 mg / kg, the patients inhaled sevoflurane by up-and-down method in the groupâ…¡(sevoflurane + midazolam group). We recorded the time of patients'losing consciousness. we also recorded mean arterial pressure (MAP), heart rate (HR), product of rhythm of the heart and systolic blood pressure (RPP), bispectral index (BIS) and heart rate variability (HRV) at the time of before induction, consciousness disappear, before and after intubation.Results: ED₅₀ of sevoflurane in groupâ… is 3.52 (%),and its 95% confidence interval is 3.46%～3.57%. In groupâ…¡, ED₅₀ of sevoflurane is 2.61% while using midazolam, and its 95% confidence interval is 2.52%～2.70%. In groupâ… , compared to before induction there is significant statistical differences in MAP, HR, LF,LF/HF at the time of before intubation.(p<0.01) After intubation, MAP, HR, LF,LF/HF have significant changes compared to before intubation. (p<0.01)â… group after intubation HR,MAP,RPP ,BIS of 60 and less than 60 to have reached statistical significance. (p<0.05)PRR> 12000. In group II, compared to before induction, there are significant statistical differences in MAP, HR, LF,LF/HF at the time of before intubation. (p<0.05).After intubation, MAP, HR, LF,LF/HF changes have no significant difference compared to before intubation (p>0.05). Inâ…¡group RPP after intubation, BIS 60 and less than 60 to have reached statistical significance. (p<0.05) PRR <12000. With BIS 60 there are significant differences in groupâ… andâ…¡in the aspects of sevoflurane concentration, time of loss consciousness. (p<0.01)Conclusion: with only sevoflurane inhalation induction, the ED₅₀ of sevoflurane is 3.52% with BIS 60. 95% confidence interval is 3.46%～3.57%. Combined with midazolam, the ED₅₀ of sevoflurane is 2.61% with BIS 60. 95% confidence interval is 2.52%～2.70%. In the rapid induction with sevoflurane, when BIS is reached 60 as recommended before intubation, post-intubation blood pressure and heart rate still increased significantly. Combining with midazolam provides more stable hemodynamic changes, cardiac autonomic nerve function activities and higher patient satisfaction.