الفهرس 
Review of literatureOnly 14 pages are availabe for public view
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Abstract
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.
Group I: the depth of anesthesia was monitored using the traditional clinical signs.
Group II: the depth of anesthesia was monitored using bispectral index scale.
Group III: the depth of anesthesia was monitored using the spectral entropy monitoring .
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All patients were premedicated with oral midazolam 0.2 mg/kg to a maximum of 15 mg two hours before transfer to the operating room, Hemodynamic monitoring was carried out using Datex Ohmeda S/5 and Aisys anesthesia machines for continuous monitoring of 3-lead ECG, heart rate, invasive arterial blood pressure, core temperature, oxygen saturation , end-tidal carbon dioxide, end-tidal desflurane and desflurane amount at end of surgery. All were continuously monitored and recorded every 20 min, body temperature was maintained using forced air warmer and iv fluid warmer.
Upon arrival in the operating-theatre Anesthesia was induced with intravenous propofol 2mg/kg ,fentanyl 1ug/kg ,followed by continuous remifentanyl infusion of 0,1 ug/kg/min using the Alaris Imed Gemini PC-2TX Infusion Pump Dual-Channel Infusion System. Laryngoscopy and tracheal intubation were facilitated with intravenous cisatracurium 0,15 mg/kg.
Anesthesia was maintained with desflurane/remifentanyl in 40% oxygen in air. All patients were mechanically ventilated with 40% oxygen in air to maintain end-tidal CO2 concentration of 34- 36 mmHG.
A soda lime absorbent circuit was used using total fresh gas flow of 2 litres/minutes.
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In group I, the desflurane concentration was adjusted according to standard clinical practice to maintain hemodynamical stability (maintaining mean arterial pressure and heart rate within 20% of baseline) and to provide a rapid recovery.
-The criteria for inadequate anesthesia were considered to be:
1. An increase in mean arterial pressure more than 20% of baseline.
2. Heart rate more than 90 beats/min in the absence of hypovolaemia.
3. Other autonomic signs such as sweating or flushing.
4. Somatic responses such as movement or swallowing.
In group II BIS monitoring was done by A-2000 BIS monitor (version XP,Aspect Medical System) which is already integrated into the datex –ohmeda S/5 anesthesia monitor. Data were acquired using a proprietary 4-point BIS-QUATRO adult electrode(Zipprep, Spect Medical System, Newton MA,USA) applied to the forehead in the manner recommended by the manufacturer.BIS values were recorded preoperatively and each 20 min during surgery.
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In group III , Anesthetic depth was measured by means of spectral entropy and the entropy sensors with 3 points attachments to the patient’s forehead were placed after cleaning with alcohol sponge.SE & RE were recorded preoperatively and each 20 min during surgery.
Measuring the plasma level of epinephrine, nor-epinephrine and cortisol to all patients was done preoperatively, hourly after induction of anesthesia and during signs of inadequate anesthesia .
Recovery was assessed by measuring time to extubation and time to achieve a modified aldrete score of 9.
All groups were compared for amount for amount of hypnotic drug consumptions , recovery profile , incidence of awareness , signs of inadequate anesthesia, and effect on stress response to surgery by measuring the plasma level of catecholamines and serum cortisol.
Our study revealed that the used of anesthetic depth monitoring for titration of the hypnotic anesthetic agents was associated with significant reduction in desflurane consumption. We found 6.5% reduction in the BIS group while 29% reduction in the entropy group, as it was 93.67±1.369 ml/hr in control group, 87.8±0.365 ml/hr in BIS group and 66.7±0.286 ml/hr in entropy group.
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Hemodynamic parameters were comparable in the three groups with no statistical significance.
Reduction of the hypnotic anesthetic consumption was not associated with stress hormones release and non of our patients reported intra operative awareness regarding the monitored groups in a standardized postoperative interview.
We also found that BIS and entropy(SE & RE) performed well in their ability to show concordance with clinically observed anesthetic depth, with superiority of entropy on early detection of corticocerebral arousal, inadequate hypnosis and uncovered nociception before elevation of stress responses and increase risk of recall of events. As regard the recovery from anesthesia it was significantly shorter in entropy group as regard time to extubation.
Our conclusion was that:
1. Titration of the hypnotic anesthetics using BIS index and spectral entropy was associated with significant reduction of anesthetic consumptions with no incidence of intraoperative awareness.
2. Titration of the hypnotic anesthetics did not induce release of stress hormones in response to surgery especially in the presence of a potent narcotic.
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3. Spectral entropy challenges other consciousness monitors by offering an index that directly separates the activity caused by the frontal muscle EMG from the EEG activity.
4. Spectral entropy charts the level of consciousness just as reliably as BIS but with early detection of corticocerebral arousal, inadequate hypnosis and uncovered nociception before elevation of stress responses and increase risk of recall of events.
5. Use of spectral entropy module is associated with less frequent intraoperative interference(i.e., artifacts) than BIS.
6. Titration of the hypnotic anesthetics using spectral entropy was associated with faster emergence from anesthesia, shorter PACU stay and improved quality of recovery by reducing the incidence of postoperative recall.