Percentage of beta 2 band power of quantitative pharmaco-electroencephalography decreases in propofol anesthetized rabbits A dose-dependent analysis

摘要

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 latent period (r =-0.94, 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 β2-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.