Biphasic effects of propofol on the percentage of alpha2-band power of quantitative pharmaco-electroencephalography of rabbits / 中国组织工程研究

ABSTRACT

BACKGROUND: Quantitative pharmaco-electroencephalography (QPEEG) can reflect cerebral cortical function, which can be certainly affected by general anesthetics. Anesthesia depth has good correlation with the anesthetic dosage, so if we can find out the areas of brain and band of QPEEG which is relative to the anesthetic dosage, the band may be taken as the index to reflect the depth of anesthesia. OBJECTIVE: To observe the effects of propofol on the alpha2-band (α2- band) of QPEEG in rabbits. DESIGN: A randomized control animal experiment. SETTING: Jiangsu Provincial Key Laboratory of Anesthesiology, Xuzhou Medical College. MATERIALS The experiment was carried out in the animal laboratory of Xuzhou Medical College from October 2004 to August 2005. Thirtysix healthy adult rabbits were randomly divided into propofol 2.5, 5 and 10 mg/kg groups with 12 rabbits in each, including 6 were used to observe the change of percentage of each band power of QPEEG, and the other 6 were used to observe the latency and duration for the disappearance of righting reflex in the rabbits. METHODS: The experiment was performed between 1400-1700 every day. Rabbits in the three groups were treated with intravenous injection of propofol of 2.5, 5 and 10 mg/kg respectively within 30 seconds. ① The conscious rabbits were fixed onto the platform in a prone osition, and the QPEEG was recorded with the method of power spectrum analysis before administration and at 20, 30, 40, 50, 60, 70, 80, 90, 100 and 110 s and 2, 5, 10, 15, 20 and 30 minutes after administration respectively. The sampling time for each time point was 5 s. ② The latency and duration for the disappearance of righting reflex in the rabbits were recorded. RESULTS: ll the 36 rabbits were involved in the analysis of esults. ① After the intravenous injection of propofol, the righting reflexes all disappeared within 1 minute. The greater the dosage, the shorter the latency and the longer the duration r=0.79, P ＜ 0.01). ② Compared with before administration, propofol of 2.5 mg/kg had no obvious influence on the percentage of α2-band power (P ＞ 0.05); The percentages of α2-band power in the brain areas were increased after administration in the propofol 5 mg/kg group (P ＜ 0.05); Except that there were no significant differences in the left and right parietal regions between the propofol 10 mg/kg group and the propofol 5 mg/kg group, the percentages of α2-band power in the other brain areas in the propofol 10 mg/kg group were decreased as compared with those before administration and those in the other two groups (P ＜ 0.05), and the changes above were more obvious in the frontal and temporal regions.CONCLUSION: The influence of propofol on the percentage of α2-band power of QPEEG is biphasic, it is suggested that α2-band would be an index to reflect the anesthesia depth of propofol.