CORTICAL ACTION POTENTIALS DURING ANESTHESIA

Abstract

Cortical action potentials under 17 anesthetic agents (nitrous oxide, cyclopropane, ether, divinyl ether, ethylene, trichlorethylene, ethyl alcohol, ethyl chloride, ethyl urethane, chloroform, amylenehydrate, tribromethanol, "evipal," paraldehyde, sodium bar-bital, chloralosane, and "nembutal") were studied in the cat, under "standard" conditions at 2 given levels of anesthesia. Frequency of cortical waves is relatively characteristic for each agent. Frequency is not affected by sciatic stimulation, though voltage in 1 group of agents is affected, but not in another. On the basis of 8 criteria (molecular size, volatility, frequency per second of the cortical waves [fast or slow], voltage, pattern, presence or absence of a secondary cortical discharge following sciatic stimulation, type of flexor response to sciatic stimulation, ability of sciatic stimulation to alter the voltage of cortical waves under light anesthesia) the 17 agents show a marked tendency to fall into 2 quite distinct groups. The possible implications and relationships of the above findings to each other are discussed.