抄録
Changes in electroencephalogram (EEG) and heart rate were recorded in dogs during electroacupunctural analgesia (EAA). As the acupunctural point, "B1 23" was used exclusively, because it was the most reliable point to obtain successful and complete acupunctural analgesia. EEG was recorded from four points on the cerebral dura mater by using chronically implanted electrodes. An electrocardiogram was recorded simultaneously with the EEG to know changes in heart rate. EEG recorded during EAA was classified into the following five distinct stages. (1) Electrical excitation stage: When the electric current was applied via needles placed at point "B1 23" with 2-3 Vp-p, predominant waves of EEG were 30-60 Hz with 10-30 μV. These waves were of higher frequency than those of the natural resting stage of the dog. (2) Light analgesic stage: When the stimulating electrical voltage increased to 5-6 Vp-p, predominant waves of EEG showed 13-30 Hz with 10-60 μV. The pattern became synchronized and rhythmical. (3) Deep analgesic stage: When the voltage was raised to 8-15 Vp-p, the dog fell to complete analgesia. Predominant waves of EEG were 13-20 Hz with 50-220 μV. Spindling waves appeared at constant intervals. (4) Maintenance stage: After analgesia appeared all over the body, a maintenance voltage of 8-15 Vp-p was applied as long as needed. In this stage two kinds of waves of 8-13 Hz and 4-8 Hz, respectively, with 50-150 μV were predomitiant. After the stimulating current was turned off, EEG of the recovery stage was also recrded. No significant changes in heart rate could be seen between the resting stage before charging electricity and the deep analgesic stage by electroacupuncture. From the record of EEG and heart rate, the level of consciousness of the dog during complete analgesia caused by electroacupuncture may correspond to that of the drowsy stage in natural or light sleep when a general anesthetic was used.
