The Feasibility of Bispectral Index Monitoring: DISCUSSION

In: Anesthesia

16 Sep 2009

The Feasibility of Bispectral Index Monitoring DISCUSSIONThe benefits of bispectral index monitoring include improvement in regulation of anesthesia and reduction of anesthetic dose. We have described the usefulness of bispectral index monitoring in oral surgery under general anesthesia. The aim of the present study was to investigate the benefits of bispectral index monitoring for intravenous sedation during dental treatment. Since the bispectral index is directly proportional to the intravascular concentration of propofol at the level of light sedation, bispectral index monitoring is expected to be a useful sedation monitor under intravenous sedation. However, since the site of surgery is the maxillofacial region and neck in dental treatment and oral surgery and since no neuromuscular blocking drugs are used, monitoring may be excessively interrupted by artifacts such as EMG input under intravenous sedation during dental treatment.

Concerning the assessment of the reliability of data, an SQI of 15% or more, which is indicated by Aspect Medical Systems, is generally considered necessary. However, in dental treatment and oral surgery, the artifact rate is high, and comprehensive evaluation, including EMG and impedance such as that using Johan-sen and Koitabashi’s criteria, may be necessary. In the present study, the surgeons were careful to keep stimulation of the patient’s head to a minimum and attached the bispectral index monitor sensor securely to the head using gauge and tape (Transpore 3M). Sleigh et al reported that the frontal muscles have little effect on EEG. However, in the present study, the bispectral index score under intravenous sedation with spontaneous ventilation was easily affected by EMG input due to body movement, since no neuromuscular blocking drug was used. Artifactual data due to eye movement also appeared to affect the bispectral index score. Therefore, EMG input and impedance were higher in the IVS group than the GA group, and consequently SQI and the number of “good” EEGs were lower. discount prevacid

Nonetheless, the incidence of “good” EEGs (EEGs satisfying all of the following: EMG input < 50 dB; SQI > 25%; and impedance < lOkfl) was 82.4% ± 9.2%, indicating that bispectral index monitoring is still a useful monitor when combined with clinical standards such as the Observer’s Assessment of Alertness Sedation Score and the Ramsay score. Moreover, Johansen and Seble noted that there have been a number of improvements in the bispectral index monitor, and artifacts such as EMG input can now be easily eliminated. Consequently, the bispectral index monitor is expected to play an increasingly important role in intravenous sedation as a sedation monitor, since future improvements, such as eliminating artifactual noise, will improve reliability. Currently, the bispectral index monitor is mainly used as a monitor of depth of anesthesia. However, in the near future, it is anticipated that the monitor applying the auditory evoked response will be suitable for use in dental treatment. Effective combination of the various sedation monitors available will allow easier control of the sedation level, thereby rendering anesthesia control more quantitative and safe. Since the number of the subjects was small (n = 14) in this study, further studies with additional subjects are necessary. viagra online pharmacy

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