A patient’s hypnotic state can be evaluated in real time using several devices that quantify the electroencephalogram (EEG). Among them, the Bispectral Index monitor (BIS; Aspect Medical Systems, Newton, MA) uses the bispectral analysis of the EEG, while the Entropy Module (GE Healthcare, Helsinki, Finland), based upon spectral entropy, describes the irregularity, complexity, or unpredictability characteristics of a signal ,The use of such EEG monitors can decrease drug consumption during anesthesia and lead to a faster recovery from anesthesia . The use of the Bispectral Index™ (BIS) monitor may decrease the incidence of intra operative awareness. Whereas the BIS monitor uses different algorithms to calculate the BIS during the different stages of anesthesia, e.g., burst suppression (BS) and frequency power calculation , as well as bispectral analysis , the Entropy Module™ measures depth of anesthesia with a single algorithm, i.e., calculating the Shannon Entropy of the power spectrum called the Spectral Entropy. The Entropy Module™ calculates two different Spectral Entropy indicators: The state entropy (SE), computed over the frequency range from 0.8 to 32 Hz, reflecting the EEG-dominant part of the spectrum, in addition to the response entropy (RE), computed over the frequency range of 0.8 to
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47 Hz, including both the EEG and electromyographic (EMG) dominant part of the recorded spectrum .
The aim of this study was to compare spectral entropy monitoring , bispectral index monitoring , with the traditional clinical monitoring in patients underwent spine surgeries and the impact of depth of anesthesia monitoring on the dosage consumption of anesthetics, incidence recall awareness and emergence from anesthesia. This was done after After obtaining institutional review board approval and written informed patient consent, 120 adult patients A.S.A physical status I or II classification recruited to undergo spine surgeries were enrolled in this study. Patients with cardiovascular ,respiratory ,metabolic, renal ,hepatic diseases and history of drug abuse were excluded from the study. Patients were categorized randomly into 3 equal groups each of 40 patients. |
