Electroencephalogram Characteristics of Surgical Anesthetized Patients and Postoperative. Dilirium

Purpose：Construct a perioperative EEG database for elderly patients under general anesthesia, and explore the correlation between their EEG spectrum characteristics and the occurrence and severity of postoperative delirium. Content：This study aims to investigate patients undergoing elective orthopedic surgery, analyze the changes in perioperative EEG spectrum, correlate with the occurrence and severity of POD, and explore the relationship between perioperative EEG changes and the development of postoperative delirium. Method: Patients aged over 60 years old who are scheduled for orthopedic surgery and plan to stay in hospital for more than two days were selected. All patients underwent preoperative MMSE and 3D-CAM assessments. Subsequently, anesthetic depth monitor electrodes were applied to the occipital or frontal-temporal regions of the patient to collect electroencephalograms of the occipital lobe during conscious and quiet states, the frontal lobe during general anesthesia, and the recovery room. During PACU, scores were calculated based on the CAM-ICU scale evaluation. During the first 5 days after surgery, patients were evaluated every day between 13:00 and 20:00 using 3D-CAM, or at any time when they showed obvious symptoms of delirium, unless they were discharged or taking sedatives (RASS \< -3). Ten minutes after the end of the evaluation, patients' electroencephalograms were monitored in a conscious and quiet state, or in a state of obvious delirium. Patients were divided into a delirium group and a non-delirium group based on whether they developed delirium after surgery. The characteristics of electroencephalograms before, during, and after surgery were analyzed in both groups of patients.Research significance:The results of this study may provide objective indicators and theoretical basis for monitoring and diagnosing the occurrence and development of POD, which can help clinical doctors identify patients with increased delirium risk in the early stage, and adjust the plan in a timely manner to change the triggering risk factors of POD.

Preoperative cognitive and delirium assessment:

The MMSE scale assesses patients' preoperative cognitive function status: the total score is 30 points; the higher the score, the better the cognitive function. Considering the impact of education level on MMSE assessment, combined with the actual situation in China and previous research, we set the criteria for illiteracy or most primary and junior high school subjects as ≤17, ≤20, and ≤24, respectively. Individuals with scores lower than the corresponding criteria are considered to have preoperative cognitive impairment. Preoperative baseline values for 3D-CAM assessment of delirium status: Patients were assessed for delirium using the 3-minute Rapid Confusion Assessment Method (3D-CAM) between 13:00 and 20:00 on the day before surgery.

Postoperative delirium assessment:

During the PACU period after surgery, the score was calculated based on the CAM-ICU scale evaluation;During the first 5 days after surgery, patients undergo an evaluation via 3D-CAM between 13:00 and 20:00 every day, or at any time when they experience significant delirium symptoms, unless they are discharged or taking sedatives (RASS \< -3).

Eligibility Criteria:
Inclusion Criteria:

Patients aged ≥ 60 who undergo elective orthopedic surgery and require hospitalization for more than 2 days after surgery

Exclusion Criteria:

1. Having central nervous system diseases or mental disorders;
2. Existence of serious systemic diseases, such as heart, lung, liver, and kidney dysfunction, coagulation dysfunction, etc;
3. Frequent use of psychotropic drugs, opioids, or corticosteroids;
4. Have a medical history of intraoperative knowledge;
5. Unable to complete preoperative delirium screening due to severe blindness, deafness, illiteracy, or Mandarin proficiency;
6. Patients expected to undergo a second surgery within five days