EFFECTS OF THIOPENTAL, KETAMINE, DIAZEPAM, XYLAZINE, AND NITROUS-OXIDE ON EEG SPIKE ACTIVITY AND CONVULSIVE BEHAVIOR DURING ENFLURANE ANESTHESIA IN ATROPINIZED CATS - EFFECT OF INCREASING INHALANT CONCENTRATIONS

The effects of thiopental, ketamine, diazepam, xylazine, and nitrous o xide, and the combinations of thiopental-nitrous oxide and ketamine-ni trous oxide, on both enflurane-induced electroencephalographic (EEG) s pike activity and convulsive behavior were measured quantitatively in atropinized cats receiving enflurane with controlled ventilation. Pret reatments with thiopental, ketamine, and diazepam reduced both EEG spi ke frequency and amplitude at 2.5% to 4.5% inspired enflurane but did not abolish spike activity. Nitrous oxide (66% of inspired gas) did no t significantly alter spike frequency or amplitude during 2.5% to 4.5% inspired enflurane, but the combination of thiopental-nitrous oxide o r ketamine-nitrous oxide reduced EEG spike activity during 2.5% inspir ed enflurane. Enflurane-induced convulsive score was markedly suppress ed by thiopental and ketamine and was significantly reduced by diazepa m, xylazine and nitrous oxide. The combinations of thiopental-nitrous oxide and ketamine-nitrous oxide greatly reduced behavioral-convulsive responses induced by 2.5% to 4.5% inspired enflurane.