|Budget Amount *help
¥2,100,000 (Direct Cost : ¥2,100,000)
Fiscal Year 1994 : ¥200,000 (Direct Cost : ¥200,000)
Fiscal Year 1993 : ¥1,900,000 (Direct Cost : ¥1,900,000)
We examined changes in each of the indices according to nitrous oxide concentration or objectively determined sedation state, and after intravenous infusion of diazepam or midazolam, confirmed that the fluctuation of median EEG frequency and component ratios according to a frequency band computed from the EEG power spectrum reflected the depth of sedation. In the clinical component of the study, we assessed such changes in the above indices during dental treatment performed under the psychosedation and the patient's objective findings.
The results showed a median EEG frequency of 5-6Hz for inhalation of 20%-30% nitrous oxide, which generally provides optimum sedation, versus one of less than 5 Hz for inhalation of 40% nitrous oxide, which induces a sleep state. With intraveno us diazepam or midazolam, on the other hand, median EEG frequency gradually declined after an initial increase, becoming stable after the onset of sedation. The frequency band component ratios showed an increase in the a-and slow-wave components and a decrease in the fast-wave component in response to nitrous inhalation : in contrast, with the benzodiazepine derivatives an initial rise in the fast component was observed, followed by an increase in the a-component throughout the duration of the sedated state. This suggests that the initial rise in median EEG frequency with benzodiazepine derivatives is due to a fast-ware unique to benzodiazepines.
In the clinical component of the study, median EEG frequency also rose after administration of the benzodiazepine derivatives : however, frequency in the sedated state was stable, peaking whenever the patients experienced pain or the sedative effect weakened. The above findings imply that changes in median EEG frequency reflect depth of mental sedation and stress states due to pain, et c. It is concluded that median EEG frequency appears to be a useful index of the depth of psychsedation.