Reduced neural activity during volatile anesthesia compared to TIVA: evidence from a novel EEG signal processing analysis through a randomized controlled trial

Background: General anesthesia can be accomplished by inhalation-based (volatile) or total intravenous anesthesia (TIVA). While their effects on post-operative symptoms have been investigated, little is known about their influence on brain functionalities during the surgery itself. Objective: To assess differences in brain activity between volatile and TIVA anesthetics during surgery. Participants: Seventeen patients who were electively admitted for laparoscopic cholecystectomy in Galilee Medical Center, Nahariya, gave written consent to participate in the study, and were randomly divided to receive either volatile anesthesia (9), or TIVA (8). An additional 17 healthy volunteers were used as an awake control group. Outcome measures: A single bipolar EEG electrode was placed on the participants foreheads and collected their electroencephalographic data during the surgery. The signal was analyzed in two different methods. First, extracting real-time amplitudes of the classical qEEG frequency bands and second applying novel harmonic signal processing that created three novel biomarkers. Results: All surgeries were uneventful, and all patients showed less than 60 bispectral index BIS score. Brain activity under volatile anesthesia showed significantly decreased delta and beta frequencies and significant decrease in activity of two biomarkers of the novel analysis with a difference in decrease between volatile and TIVA anesthesia. These two novel biomarkers exhibited significantly higher activation in the awake control group compared to the anesthetized patients. Conclusions: Both EEG frequency bands and novel brain activity biomarkers provide evidence that volatile anesthesia reduces brain activity to a much lower extent compared to TIVA anesthesia.