  Post-operative cognitive decline is a well-known phenomenon and of crucial
importance especially in the elderly. 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. To
assess differences 17 patients were divided to receive either volatile
anesthesia (n=9), or TIVA (n=8). The level of anesthesia was kept to be equal
in both groups. A single bipolar EEG electrode (Neurosteer system) was placed
on the participants foreheads. It presented real-time activity and collected
their data during the surgery. The dependent variables included frequency bands
(delta, theta, alpha, and beta), and three features (VC9, ST4, and A0)
previously extracted with the device and provided by Neurosteer. All surgeries
were uneventful, and all patients showed bispectral index (BIS) score less than
60. Feature activity under volatile anesthesia (in comparison to TIVA) was
significantly lower for the delta, theta and alpha frequency bands and for the
three features. Further analysis showed that the largest difference between
anesthesia types was for feature A0. The EEG frequency bands and novel brain
activity features provide evidence that volatile anesthesia further reduces
components of brain activity in comparison to TIVA anesthesia. Specifically,
A0, which previously showed a correlation with cognitive decline severity and
cognitive load, exhibited the most prominent difference between anesthesia
types. Together, this study suggests that measuring brain activity during
anesthesia using sensitive features, enables revealing that different
anesthesia types may affect brain activity differently, which could affect the
recovery from anesthesia, and consequently reduce post-operative cognitive
decline
