It has been shown in previous studies that burst suppression has an effect on the development
of postoperative delirium (POD) and postoperative cognitive dysfunction (POCD). With the
development of technology, EEG-based anesthesia management is getting more and more
attention. In particular, methods that reduce anesthetic drug consumption are expected to
prevent POD and POCD by reducing burst suppression. There are studies that show that epidural
analgesia applications reduce general anesthesia drug consumption in patients receiving
general anesthesia. In this study, investigators want to investigate the effect of epidural
analgesia combined with general anesthesia on burst suppression. POD and POCD development in
these patients will be examined as secondary objectives.