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Query: EC:2.3.1.177 (BIS)
 957 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We investigated the EEG parameter changes of skin incision during different depth of sevoflurane/nitrous oxide analgesia. 65 ASA physical status I patients (aged 34 +/- 12 yr) scheduled for elective abdominal surgery were studied. The tracheal of each patient was intubated and the lungs were ventilated. Patients were randomly assigned to one of three groups. Anesthesia was maintained with 1% (group I n = 25), 1.5% (group II n = 20) or 2% (group III n = 20) end-tidal sevoflurane concentration in 66% nitrous oxide. Each of the concentration levels was maintained for at least 15 minutes before surgical incision. The EEG electrodes were placed on each patient in a front-oparietal montage (Fp1- A1, Fp2- A2) referred to Cz. EEG was recorded during 3-min period before incision. Hemodynamic variables were also monitored. Inadequate anesthetic depth was defined as patient movement in response to a 5-cm skin incision. The ventilation was controlled to maintain normocapnia (PETCO2 5 +/- 0.04 kPa). The data were analysed using ANOVA, liner correlation analysis and t-test. A significant difference between EEG parameters (SEF, BIS,) and skin incision responsive rate were found among the three concentration groups (P < 0.01). There were no difference of hemodynamics among the three groups. Patients who moved at incision also had significantly higher SEF, BIS leveles compared to non-movers (P < 0.01). Quantitative EEG determinants were correlated well with the end-tidal sevoflurane concentration and were a useful predictor of patient movement in response to skin incision during sevoflurane/nitrous oxide anesthesia.
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PMID:[Quantitative electroencephalogram monitoring the depth of anesthesia during skin incision]. 1067 83

We investigated the effect of intraoperative bleeding on the changes in estimated and measured blood concentrations of propofol, and the relationship between anesthetic effect of propofol and serum albumin concentration in a patient undergoing prostatectomy during propofol/epidural anesthesia. The rate of propofol infusion was titrated to keep the BIS value about 50. The estimated blood concentration of propofol calculated by ConGrase, a program for on-line simulation of blood propofol concentration, was monitored during anesthesia. Blood samples were obtained at nine points during surgery and the blood concentrations of propofol and albumin were measured postoperatively. When the amount of bleeding reached about 2000 mg, the difference between estimated and measured blood concentrations of propofol did not increase. As the serum albumin concentration decreased, the concentration of propofol to keep bispectral index about 50 decreased. This study suggests that the change in serum albumin concentration following intraoperative bleeding is an important factor in the anesthetic effect of propofol.
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PMID:[Relationship between changes in estimated and measured blood concentrations of propofol and serum albumin concentration during propofol anesthesia: effects of intraoperative bleeding (a case report)]. 1084 89

The Bispectral Index or "BIS" is a single number, composed from different EEG features, using multivariate statistical methods. It was designed for monitoring the depth of hypnosis during anaesthesia and sedation. Empirically derived from the EEGs of more than 5,000 anaesthetised patients, the BIS reflects the effect of anaesthetics on the brain. Unlike univariate measures, such as Spectral Edge Frequency or Median Frequency, the Bispectral Index is drug independent and changes with increasing doses of hypnotics in an almost linear way. Though sophisticated technology, the A-2000 BIS monitor and the BIS sensor are easy to use and also allow non-experts to monitor the depth of hypnosis and sedation on a routine basis.
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PMID:Bispectral analysis technology and equipment. 1096 21

We studied the effect of mild hypothermic cardiopulmonary bypass (30 degrees C) on the EEG Bispectral Index in 10 patients undergoing elective CABG. BIS was recorded at 11 event-related time points during the procedure. After a significant decrease at the induction of anaesthesia, BIS was not further modified during the procedure. BIS was neither affected by surgical stimulation nor by CPB and mild hypothermia. We conclude that we did not find any reason to preclude the use of BIS to assess the hypnotic effects of anaesthetics during normothermic or mild hypothermic CPB.
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PMID:Effects of mild hypothermic cardiopulmonary bypass on EEG bispectral index. 1112 18

Inapparent adverse intraoperative wakefulness is still a relevant problem in modern anaesthetic routine. It can be associated with serious negative effects on the postoperative recovery of the patients. Several different procedures have been developed to monitor and therefore avoid intraoperative situations of wakefulness during general anaesthesia. The most promising methods are the PRST-score, calculated from changes in the blood pressure, heart rate, sweating and tear production, the so-called isolated forearm technique, spontaneous EEG and its derived parameters such as spectral edge frequencies or BIS and finally mid-latency auditory evoked potentials. The observation of clinical autonomic signs, even including the calculation of the PRST-score does not seem to be valid enough to indicate or predict intraoperative wakefulness. The isolated forearm technique can be regarded as the most reliable tool to detect intraoperative wakefulness, but it can only be applied for a very limited period of time. The processed EEG with the median frequency, spectral edge frequency or bispectral index are important scientific tools to quantify central anaesthetic effects especially to develop pharmacodynamic-pharmacokinetic models of anaesthetic action. But they seem to be less suitable to indicate situations of intraoperative wakefulness or awareness. The mid-latency auditory evoked potentials are depressed dose-dependently by a series of anaesthetic agents, which correlate with the occurrence of situations of intraoperative wakefulness and awareness. There is a hierarchical correlation between certain values of the MLAEP and intraoperative wakefulness defined by purposeful movements, amnesic awareness with only implicit recall and conscious awareness with explicit recall. For some of the most commonly used anaesthetics reasonable threshold values of the MLAEP for the different states of consciousness have already been determined. Future studies in broad patient populations with all of the different routinely used anesthetics and procedures will have to finally identify the importance of the recording of mid-latency auditory evoked potentials as a routine method to assess the depth of anaesthesia.
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PMID:[Depth of anesthesia, awareness and EEG]. 1182 82

We gave total intravenous anesthesia to an over-100% hyper-obese patient using target-controlled infusion (TCI) of propofol and fentanyl. To keep him asleep, we maintained his BIS in a range of 40 to 60 by adjusting the target concentration of propofol. For the target concentration of fentanyl, we chose 2 ng.ml-1 at incision and 1.6 ng.ml-1 during the operation. At the patient's emergence from anesthesia, his estimated blood concentration of propofol was 1.51 micrograms.ml-1 and his BIS was 80. The relationship between BIS value and effect-site concentration of propofol was almost the same as that assessed in ordinary adults of a normal weight. We conclude that the estimated concentration of propofol is a good indicator of the effect of propofol and that TCI is a useful technique in obese patients as well as in ordinary adults.
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PMID:[Anesthetic management of a hyper-obese patient by target-controlled infusion (TCI) of propofol and fentanyl]. 1142 72

Without any doubt there is an increasing need for accurately measuring depth of anesthesia - from the viewpoint of the anesthesiologist and also of the patient. The ideal monitoring should fulfill the following criteria: It should be applicable for any type of anesthesia (intravenous as well as inhalative anesthesia); the monitor must have an extremely high sensitivity (each patient being awake must be recognized by the device).If the monitor does not have a high sensitivity, the monitor itself might lead to an increasing number of patients being awake during anaesthesia, because the anesthesiologist might rely on the monitor and does not deepen anesthesia while the patient is awake. Specificity is not as important as sensitivity. As incidence of interoperative awareness is low, one must monitor more than 750 patients to recognize only one patient who is awake. Finally, the monitoring device must be economic. If costs are considerably increased by measuring depth of anesthesia in today's climate of cost consciousness, the monitoring has to be restricted to special high risk groups of patients. If monitoring depth of anesthesia will become simple, safe, and economic, each anesthesia should be monitored for its depth, as today each patient needs pulseoxymetry. We try to give an orientation about the available devices for monitoring depth of anesthesia. Since the introduction of BIS interest in measuring depth of anesthesia is growing very dynamically. Due to the dynamic growth we hope that we were able to present an actual and complete overview about the monitoring systems for measuring depth of anesthesia. Until today no monitoring system has proven to fulfill the mentioned criteria. Monitoring of the depth of anesthesia will be based on any processing of the spontaneous EEG or its evoked potentials. Which type of monitoring, entropy, BIS, PSI, or MLAEP will be used in clinical routine will be shown in the future. All available monitors are no predictors, whether depth of anesthesia is sufficient for the next painful surgical stimulus. They can only monitor the anesthetic state at the time of measurement. There is no "golden number" predicting absolutely safely that the patient is in adequate anesthesia. The anesthetist must consider any technique for monitoring of the depth of anesthesia as an additional help in improving care for his patient.
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PMID:[Is measuring the depth of anesthesia sensible? An overview on the currently available monitoring systems]. 1170 93

Spontaneous EEG has been proposed for monitoring depth of anaesthesia and adjusting anesthetic drugs doses. This review describes the main features of spontaneous EEG, the principles of EEG signal analysis used in anaesthesia, and the EEG effects of the different anesthetic drugs in adults and children. Then, the correlations between EEG parameters changes and clinical signs of anesthesia (loss of consciousness and memory, lack of movement and haemodynamic stability despite noxious stimulations) are analyzed. The best signal analysis technique available today for routine use seems to be bispectral analysis, which returns, in the available monitors, a single number called bispectral index or BIS. Based upon the recent literature, clinical uses, performances and limits of use of BIS are described and discussed.
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PMID:[Automatic analysis of electroencephalogram: what is its value in the year 2000 for monitoring anesthesia depth?]. 1175 14

Advances in neuromonitoring have provided insights into neurologic function during anesthesia. Despite the limitations and necessary caution when using intraoperative monitors to interpret neural function, these technologies have been definite steps in the right direction for assessing neural integrity and level of consciousness during anesthesia. The techniques discussed minimize the adverse sequelae of a variety of neurosurgical and orthopedic procedures, reducing the morbidity rates/risks in the perioperative period. Furthermore, it is likely that such monitoring will become a standard of care, similar to other monitoring standards such as pulse oximetry and capnography. Accurate and reliable monitoring is essential, and on-going large prospective studies comparing the processed EEG or evoked potential with definable end points in both adult and pediatric populations will be necessary. The use of monitoring, such as the BIS, may improve cost efficiency by reducing the total amount of drug used to maintain anesthesia, as well as enhance recovery. A danger in this process, however, is the potential for public opinion, outside regulatory bodies, or medico-legal implications to drive change and enforce standards of care before appropriate data are available.
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PMID:Neuroanesthesia. Innovative techniques and monitoring. 1189 2

The depth of xenon anesthesia was never evaluated by modern methods of EEG monitoring, and hence, we studied changes in EEG, INEEG, and BIS during different stages of xenon narcosis and evaluated the possibility of using these values as criteria of xenon anesthesia adequacy. The study was carried out in 60 patients during laparoscopic operations on abdominal organs. The patients were divided into 2 groups receiving different gas anesthetics (xenon or nitric oxide). The results indicate that xenon monoanesthesia caused dose-dependent changes in the native and treated EEG; xenon is a good inhalation anesthetic providing adequate anesthesia for little traumatic operations even in case of mononarcosis; INEEG and BIS monitoring during xenon anesthesia allows an objective evaluation of its depth.
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PMID:[Electroencephalogram, informational saturation of electroencephalogram, and bispectral index during xenon anesthesia for laparoscopic operations]. 1222 74


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