A new model for anesthesia depth measurement for isoflurane, using Electroencephalogram

Concerning the limitations in monitoring the depth of anesthesia, invention and improvement of devices for monitoring the depth of anesthesia has always been one of the most important priorities in anesthesiology in recent years. Since the invention of these devices, all of them worked on a quantitative basis, so we decided to obtain a theoretic model using Electroencephalogram signals for evaluating the depth of anesthesia during isoflurane maintenance. Forty patients ASA class I, II between 15-65 year-old candidate for less than 3 hours surgery were chosen randomly. Induction for all of the patients was the same. EEG data were obtained and recorded one minute prior to induction up to the end of surgery and assessed using LILEY method. Thirty seven intervening parameters were concerned individually. The required theoretic model was prepared and the effects of different parameters on model behavior, measured and identified. The presented model in this study, with a complex and flexible dynamic is able to simulate the human cortex under the influence of isoflurane. Despite the practical limitations, this study showed that it is possible to predict depth of anesthesia on a theoretic model. It seems that it could be used for a more precise monitoring of depth of anesthesia if improved.