Overview
The goal of this observational study is to compare the perioperative EEG characteristics and the incidence of short-term cognitive dysfunction in patients with postoperative delirium and non-postoperative delirium after elderly (> 65 years old) patients undergoing major gastrointestinal surgery under general anesthesia. The main question it aims to answer are: • The correlation between postoperative cognitive dysfunction and postoperative EEG features was evaluated.• To analyze the correlation between EEG characteristics and clinical risk factors of delirium after major abdominal gastrointestinal surgery under general anesthesia in elderly patients.Participants will collect EEG before and after operation and collect the incidence of postoperative cognitive function to explore the mechanism of postoperative delirium and predict postoperative cognitive dysfunction.