Morimoto Yasuhiro, Hagihira Satoshi, Yamashita Satoshi, Iida Yasuhiko, Matsumoto Mishiya, Tsuruta Syunsuke, Sakabe Takefumi
Department of Anesthesiology-Resuscitology, Yamaguchi University School of Medicine, Ube, Yamaguchi, Japan.
Anesth Analg. 2006 Sep;103(3):641-5. doi: 10.1213/01.ane.0000229699.99371.3c.
With the introduction of bispectral index (BIS) as a measure of a patient's sedation during general anesthesia, attention has been directed toward bispectral analysis of electroencephalography (EEG). In the present study we evaluated the relationship between EEG bicoherence and sevoflurane concentration. Sixteen ASA physical status I-II patients scheduled for elective abdominal surgery were enrolled in the study. Anesthesia was induced with 5% sevoflurane and maintained with sevoflurane and oxygen (50%). Just before surgery, IV fentanyl (2 microg/kg) was given and then continuously infused (2 microg x kg(-1) x h(-1)). Using software we developed, EEG bicoherence, BIS, and 95% spectral edge frequency (SEF95) were recorded at end-tidal sevoflurane concentrations of 0.5%, 0.8%, 1.1%, 1.4%, 1.7%, 2.0%, and 2.3%. Under light anesthesia, EEG bicoherence values were low. With increasing sevoflurane concentrations, 2 peaks of bicoherence emerged along the diagonal line (f1 = f2). Both the first (at around 4 Hz) and second (at around 10 Hz) grew higher (37.7% +/- 7.5% and 35.1% +/- 9.0%, respectively) as the sevoflurane concentration increased to 1.4%. However, the first peak leveled off whereas the second tended to decrease slightly with further increases in sevoflurane concentration. The BIS value decreased as the sevoflurane concentration increased and leveled off at 1.4% and higher concentrations of sevoflurane. The SEF 95 also decreased as the sevoflurane concentration increased up to 2.3%. Thus the distribution pattern of the two bicoherence peaks is likely to be better than BIS of the anesthetic effect of sevoflurane during surgery.
随着双谱指数（BIS）作为全身麻醉期间患者镇静程度的一种测量方法的引入，人们开始关注脑电图（EEG）的双谱分析。在本研究中，我们评估了脑电图双相干性与七氟醚浓度之间的关系。16例拟行择期腹部手术的ASA身体状况I-II级患者纳入本研究。用5%七氟醚诱导麻醉，并用七氟醚和氧气（50%）维持麻醉。手术前即刻静脉注射芬太尼（2μg/kg），然后持续输注（2μg·kg⁻¹·h⁻¹）。使用我们开发的软件，在呼气末七氟醚浓度为0.5%、0.8%、1.1%、1.4%、1.7%、2.0%和2.3%时记录脑电图双相干性、BIS和95%频谱边缘频率（SEF95）。在浅麻醉下，脑电图双相干性值较低。随着七氟醚浓度的增加，双相干性沿对角线出现2个峰值（f1 = f2）。随着七氟醚浓度增加到1.4%，第一个峰值（约4Hz）和第二个峰值（约10Hz）均升高（分别为37.7%±7.5%和35.1%±9.0%）。然而，随着七氟醚浓度进一步增加，第一个峰值趋于平稳，而第二个峰值略有下降。随着七氟醚浓度增加，BIS值下降，并在七氟醚浓度为1.4%及更高时趋于平稳。SEF 95也随着七氟醚浓度增加至2.3%而下降。因此，手术期间七氟醚麻醉效果的两个双相干性峰值的分布模式可能优于BIS。
