BACKGROUND:Quantitative pharmaco-electroencephalography can be used for studying the dose-effect and time-effect relationships of drugs affecting central nervous system.Therefore,it may become an effective means for monitoring the anesthetic degree of anesthetic drug in the operation.OBJECTIVE:To observe the dose-effect relationship of propofol influencing β2-band power of quantitative pharmaco-electroencephalography in rabbits.DESIGN:A randomized block design.SETTING:Department of Anesthesiology,Xuzhou Medical College.MATERIALS:Thirty-six healthy adult rabbits of either gender,weighing (2.4+0.5)kg,of clean grade,were provided by the Laboratory Animal Center of Xuzhou Medical College.The involved rabbits were randomly divided into 3 groups with 12 in each by table of random digit:high-dose propofol group,moderate-dose propofol group,and low-dose propofol group.The protocol was carried out in accordance with animal ethics guidelines for the use and care of animals.METHODS:This study was carried out in the Department of Anesthesiology,Xuzhou Medical College between August 1999 and April 2000.Rabbits in the high-dose propofol group,moderate-dose propofol group,and low-dose propofol group were injected with 10,5 and 2.5 mg/kg propofol (ZENECA Company,British,Batch No.032000),respectively.Before and after intravenous administration of propofol,percentage of β2-band power of quantitative pharmaco-electroencephalography was measured,and the latent and persistent periods when rabbit righting reflex disappeared were observed by quantitative pharmaco-electroencephalography and power spectrum analysis.MAIN OUTCOME MEASURES:① Percentage of β 2-band power of quantitative pharmaco-electroencephalography.②Latent period and persistent period of abolition of righting reflex of rabbits.RESULTS:Thirty-six rabbits were involved in the final analysis.①Effect of propofol on righting reflex of rabbits:Righting reflex disappeared within 1 minute after the rabbits being intravenously injected with propofol.The higher dose,the shorter 1atent period (r =-0.94,P＜0.01),and the longer persistent period (r=0.79,P＜0.01).Both latent period and persistent period had good correlation with propofol dose.② Effect of propofol on the percentage of β2-band power of quantitative pharmaco-electroencephalography:In the low-dose propofol group,no significant changes in the percentage of β2-band power of quantitative pharmaco-electroencephalography existed between before and after administration within 30 minutes (P＞0.05).In the moderate-dose propofol group,the percentage of β 2-band power of quantitative pharmaco-electroencephalography in each brain region except for left and right frontal areas was significantly decreased within 30 s to 5 minutes(P＜0.05),and recovered to the level before administration 10 minutes later.In the high-dose propofol group,the percentage of β2-band power of quantitative pharmaco-electroencephalography in each brain region was significantly decreased from 20 s to 5 minutes after administration (P＜0.05-0.01),and that was gradually recovered to the level before administration 5 to 10 minutes after administration.This tendency was basically the same as the changes of latent period and persistent period.CONCLUSION:Propofol decreases the percentage of β 2-band power of quantitative pharmaco electroencephalography in dose-dependent manner.It indicates that β2-band power might become one of indexes for reflecting the anesthetic degree of propofol.