Griffiths M J, Preece A W, Green J L
University of Bristol Dental Hospital, United Kingdom.
Anesth Prog. 1991 Nov-Dec;38(6):227-31.
Real-time electroencephalographic power spectra were obtained for a group of 37 volunteers undergoing sedation with enflurane at different concentrations in air. In part one, 17 subjects were given 0.5%, 0.75%, and 1.0% for 4 min at each level, and recovery after 5 min was assessed by the Trieger method. There was considerable variation in subject response to the different doses, but adequate sedation was indicated by the presence of a strong alpha rhythm (9-11 Hz) and suppression of frequencies below 5 Hz. Overdose was indicated by an initial shift in the alpha frequency to a lower value (6-7 Hz) followed by the appearance of delta waves (0.5-4 Hz) and loss of alpha waves. In part two, 20 volunteers inhaled enflurane at 0.5% for 10 min to allow adequate absorption, followed by a 10-min recovery period. Equal numbers showed sedation or a failure to respond to enflurane at this concentration. In the responders, sedation was accompanied by a marked shift in the ratio of the power in two frequency bands: 1-4 Hz and 8-12 Hz. Progress of the frequency band power ratio followed closely the state of the subject into sedation, overdose, and recovery. This measure was further improved by the use of multivariate analysis, which showed good discrimination of the alert, sedated, and overdosed states of the subject.
对一组37名志愿者进行了实时脑电图功率谱测定，这些志愿者在空气中吸入不同浓度的安氟醚进行镇静。在第一部分中，17名受试者在每个浓度水平下分别吸入0.5%、0.75%和1.0%的安氟醚4分钟，5分钟后用特里格方法评估恢复情况。受试者对不同剂量的反应存在很大差异，但出现强α波（9 - 11赫兹）和5赫兹以下频率的抑制表明镇静效果良好。过量用药表现为α波频率最初向较低值（6 - 7赫兹）偏移，随后出现δ波（0.5 - 4赫兹）且α波消失。在第二部分中，20名志愿者吸入0.5%的安氟醚10分钟以使其充分吸收，随后有10分钟的恢复期。在这个浓度下，表现出镇静或对安氟醚无反应的人数相等。在有反应者中，镇静伴随着两个频段功率比的明显变化：1 - 4赫兹和8 - 12赫兹。频段功率比的变化与受试者进入镇静、过量用药和恢复的状态密切相关。通过多变量分析，这一测量方法得到了进一步改进，多变量分析显示对受试者的清醒、镇静和过量用药状态有良好的区分能力。
