Halliburton J R
p4iformed Services University of the Health Sciences, Graduate School of Nursing, Rockville, MD, USA.
CRNA. 1998 May;9(2):39-43.
The possibility of awareness during general anesthesia causes apprehension for the patient and the Certified Registered Nurse Anesthetist (CRNA). The goals of general anesthesia are to prevent the sensation of pain and produce a state of sedation, hypnosis, and unconsciousness so the patient will not remember the surgical procedure. An inadequate level of anesthesia can result in patient awareness during surgery. The current practice of anesthesia relies on indirect hemodynamic measurements such as blood pressure and heart rate to monitor the sedative hypnotic state of the patient's brain during general anesthesia. Hemodynamic responses are not reliable for predicting awareness just as blood pressure and heart rate are not indicative of consciousness. Electroencephalogram (EEG) waveforms are known to be affected by anesthetics. Characteristic EEG waveforms are a direct indication of the patient's level of consciousness. Unprocessed and computer-processed EEG recordings have been used in an attempt to monitor the patient's level of consciousness during general anesthesia. A raw or unprocessed EEG recording to monitor the level of consciousness during general anesthesia is problematic. The EEG signal is complex, affected by artifact, and it requires a dedicated interpreter. Conventional processed EEG monitoring systems are problematic because of the complexity of the equipment and technical difficulty of reading the EEG recording. The purpose of this article is to describe the history of awareness during anesthesia and introduce a new processed EEG monitor, the Bispectral Index (BIS) (Aspect Medical Systems, Inc., Natick, MA) with implications for future clinical use and research.
全身麻醉期间知晓的可能性让患者和注册麻醉护士（CRNA）感到担忧。全身麻醉的目标是防止疼痛感觉，并产生镇静、催眠和无意识状态，以便患者不会记住手术过程。麻醉水平不足可能导致患者在手术期间知晓。当前的麻醉实践依靠间接血流动力学测量，如血压和心率，来监测全身麻醉期间患者大脑的镇静催眠状态。血流动力学反应对于预测知晓并不可靠，正如血压和心率并不表明意识状态一样。脑电图（EEG）波形已知会受到麻醉剂的影响。特征性EEG波形是患者意识水平的直接指标。未经处理和经过计算机处理的EEG记录已被用于尝试监测全身麻醉期间患者的意识水平。使用原始或未经处理的EEG记录来监测全身麻醉期间的意识水平存在问题。EEG信号复杂，受伪迹影响，并且需要专业的解读人员。传统的处理后EEG监测系统存在问题，因为设备复杂且读取EEG记录存在技术难度。本文的目的是描述麻醉期间知晓的历史，并介绍一种新的处理后EEG监测仪，脑电双频指数（BIS）（阿斯派克医疗系统公司，马萨诸塞州纳蒂克），以及其对未来临床应用和研究的意义。
