麻醉剂浓度对大鼠暴发-抑制脑电特征的影响

The Effect of Anesthetic Concentration on Burst-suppression of the EEG in Rats

暴发-抑制脑电图(EEG)是深度麻醉状态下EEG活动受到严重抑制的表现。为定量研究暴发-抑制波形特征与麻醉剂浓度之间的关系,本文采用暴发-抑制比、暴发频率、暴发幅度和抑制幅度4个时域指标,分析大鼠麻醉模型在不同异氟烷浓度下的EEG特征。结果表明,暴发-抑制脑电的4个指标均随异氟烷浓度的改变而变化:异氟烷浓度越大,暴发-抑制比和暴发幅度越大,暴发频率和抑制幅度越小。暴发-抑制比可快速反映异氟烷浓度的变化,且个体间一致性高,有潜力作为深度麻醉状态下暴发-抑制EEG较理想的特征指标。

The term ＂burst-suppression＂ is used to describe the electroencephalogram（EEG） pattern characterized by θ or δ waves,at times intermixed with faster waves,and intervening periods of relative quiescence.Burst-suppression pattern can reflect the seriously suppressed brain activity under deep anesthesia.To investigate the relationship between burst-suppression features and anesthetic concentration,we adopted four straightforward indexes,i.e.,burst-suppression ratio（BSR）,burst frequency,burst amplitude and suppression amplitude,and used them to analyze the EEG recordings in ten isoflurane-anesthetized rats.It was found that all the four burst-suppression indexes changed along with anesthetic concentration,that BSR and burst amplitude increased with higher concentration of isoflurane while burst frequency and suppression amplitude decreased,and that BSR was the most sensitive and consistent measurement to indicate isoflurane concentration so it constituted a valuable tool for timely evaluation of burst-suppression feature under deep anesthesia.The result also showed that the composition of carrier gas（i.e.pure oxygen vs.mixed oxygen） did not influence the effect of anesthesia significantly;and the four indexes of burst-suppression features could keep relatively stable within 60min under the isoflurane concentration of 2%.The present study provides quantitative information of burst-suppression features under different anesthetic depth and may help to develop a clinically satisfied system that could quantify the characteristics of EEG and rigorously evaluate the cerebral state of patients.