Quantitative analysis of the effects of volatile anaesthetics on cortical electroencephalographic activity

Methoxyflurane, halothane and enflurane were compared in respect of their ability to modify cortical activity in Sprague-Dawley rats with chronically implanted electrodes. An analytical instrumentation system for analysis of the electroencephalogram (e.e.g), equipped with a memory unit and capable of obtaining on-line analysis of time histograms of the e.e.g. was used. Methoxyflurane was found to be four times as potent as enflurane, and 2.6 times as potent as halothane 15 to 25 min after the commencement of anesthesia. Halothane was found to be 1.5 times as potent as enflurane.