In elderly patients aged over 60 years undergoing femur surgeries anesthetized with inhalation anesthetics, electroencephalograms (EEG) and visual evoked potentials (VEP) were recorded for the purpose of the obtaining the optimal depth of anesthesia.
On EEG recording, alpha- and beta-waves were observed predominantly before induction of anesthesia. But high voltage slow waves were increasing in proportion to the depth of anesthesia, following transient fast waves caused by initial inhalation of enflurane with nitrous oxide. After optimal anesthetic depth was evaluated by means of clinical vital signs, EEG revealed high voltage slow waves including 30-50% of theta-waves which was not recognized before induction of anesthesia.
The latency of largest positive peak wave (Pmax) observed later than 170msec after photic stimulation was 207.1msec on arrival to the room, and 287.9msec at the time of establishment of optimal anesthetic depth.
These results of our study suggest that the changes in appearance rate of high voltage slow waves and Pmax in VEP can be available indicators of central nervous system monitoring during inhalation anesthesia.

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This work was conducted to evaluate various factors influencing patients' sedation under spinal anesthesia using the theory of quantification.
Materials and Methods:
The study was carried out on adult 108 ASA graded 1-2 patients. They were divided into 3 groups according the degree of sedation; Group 1 (30 patients) control, Group 2 (29 patients) was given i.v. injection of 0.1mg/kg diazepam, Group 3 (49 patients) was given 6l/min of 30% nitrous oxide for 10 minutes from the arrival into the operating room, then given 3l/min of the same concentration of nitrous oxide through the nasal cannula. Each group was divided into further subgroups, a) given their favorite music with headphone or b) not given the music.
The scale for the mesurement of degree of sedation was divided into 6 grades from 1 (no sedation) to 6 (no reaction after strong stimulation). The degree of the sedation were recorded 4 times throughout study.
After evaluation of the effectiveness of sedation, gravity and interrelation of contributing factors to anxiety were analyzed using the theory of quantification.
Results:
Sedative scores were significantly different before and after anesthesia, but no significant difference were found among six groups. Statistical analysis showed female patients, patients without anesthetic history and unstandard constitution and patients given bone surgery tended to show less effective for sedation.
Discussion and Conclusion:
Results indicate the spinal anesthesia itself was outstandingly effective to cure patients from their anxieties. However treatment with diazepam, nitrous oxide and music were found to be not additive. For obtaining the most effective sedation of patients during spinal anesthesia, it is concluded that anesthesiologist should explain how the spinal anesthesia be done to remove psycological anxieties, choose the most appropriate premedication and be ready to switch to general anesthesia when the patients' condition indicates.

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