Study Of Hypnotic Interactions And Bispectral Index Between Propofol And Midazolam

Objectives: To study hypnotic interactions between propofol andmidazolam;To compare the prediction probability between propofol andmidazolam。Methods: Seventy-five ASAⅠ～Ⅱpatients aged 20-50y,weighing40～80 kg, undergoing elective upper abdominal surgery were randomizedto,propofol(n=25),midazolam(n=25),propofol-midazolam,combination(n=25) group。Each group were further divided into 5 subgroups。Propofol0.80,1.00,1.25,1.56,1.95mg/kg was given in 5 propofol subgroupsrespectively。Midazolam 0.08,0.10,0.13,0.16,0.20mg/kgwas givenin 5 midazolam subgroups respectively。Propofol/midazolam0.250/0.035,0.310/0.045,0.390/0.056,0.490/0.070,0.610/0.087 mg/kgwas given in 5 propofol-midazolam subgroups respectively。Two minutesafter drugs administration,the patients were asked to open their eyes。Failure to open was taked as the start-point of hypnotic effect。When thepatients failed to respond to verbal order twice consecutively, the patientwas considered to be in hypnotic state。Those who still got hypnoticeffect in E and M group was gived drug by slow titration in incrementsjudged by the investigator to reach an OAAS score of 3。SBP,DBP,HR,SpO2 and BIS were monitered every one minute before, duringand after drugs administration。ED₅₀ of propofol,midazolam and propofol-midazolam combination for hypnotic effect were calculated。Isobologram was drawn to judge the hypnotic interactions betweenpropofol and midazolam。BIS prediction probalility(PK) was comparedbetween drugs。Results: The ED₅₀ for hypnotic effect was 1.10 mg/kg in group E;0.12mg/kg in group M; 0.34/0.05 mg/kg in E/M group。The deviation ofthe location of ED₅₀of E/M combination from the connecting line wasstatistically significant。Bispectral Index of responders to voice wassignificantly different from nonresponders。BIS was a better predictor ofpropofol sedation than midazolam (P_K=0.87±0.11VS 0.69±0.01)。Conclusions: The hynoptic interaction between propofol andmidazolam was synergitic。In terms of hemodynamic stability,propofolhad more outstanding influence。BIS was a better predictor of propofolsedation than midazolam。Individual BIS scores demonstrate siginificantvariability。...