The occurrence of delirium in elderly patients decreases the patient's quality of life, increases medical costs, increases long-term cognitive decline, and increases complications and mortality. Prediction and early diagnosis are important for the prevention and proper treatment of delirium after surgery, however, accurate and efficient clinical examination methods have not been developed.

Recently, a study has been published that the occurrence of delirium after surgery is related to the depth of anesthesia during general anesthesia, the burst-suppression ratio, and the symmetry of bilateral EEG. In this regard, we decided to investigate whether the perioperative change of EEG connectivity in elderly patients can predict the occurrence of delirium after the non-cardiac surgery.

In this study, the EEG signals during the perioperative period are processed with various mathematical algorithms to calculate EEG connectivity. Then, the EEG connectivity changes are compared with the results of the postoperative confusion assessment method(CAM) to validate its relation with the occurrence of the delirium. Additional EEG parameters such as the change of power spectral density and the burst-suppression ratio will also be investigated to find out the relationship with the postoperative delirium. By integrating the abovementioned EEG parameters and the known risk factors of delirium, we wish to develop a more accurate and efficient clinical diagnostic method.

Cohort/Group Label

The elderly patients age over 65, undergoing conc-cardiac surgery with the general anesthesia.

Cohort/Group Description

First, the day before the surgery, the K-MOCA test, and the Hospital Anxiety and Depression Scale test are performed on the participant to evaluate the preoperative cognitive function. On the day of the surgery, after re-confirm the consent of the participant, the investigator collects the 15 mins of the preoperative EEG data at the pre-treatment room. After entering the operating room, ordinary anesthetic care is provided to the participant, and EEG data is collected during the surgery. During the surgery, demographic data of the participant, ASA classification, medical history, type and use of an anesthetic agent, amount of transfusion, narcotic analgesic use, antiemetic use, and total anesthesia time are recorded. After the surgery has done, the investigator collects the postoperative EEG data at the post-anesthesia care unit for 30 minutes at the PACU. At the PACU, the pain scale evaluation, narcotic analgesic use, antiemetic use, and confusion assessment method(CAM) results(15 and 60 minutes after entering the PACU) are recorded. To evaluate postoperative cognitive function, the CAM is conducted to the participant on the postoperative day of 1, 2, 3, and the day before the discharge day. On the day before discharge, K-MOCA and hospital anxiety and depression scale tests are performed once more.

Not collect nor Archive

The elderly patients age over 65, undergoing non-cardiac surgery with the general anesthesia.

simple random sampling

Gender

Age

Description

The elderly patients age over 65, undergoing non-cardiac surgery with the general anesthesia.

① In case of emergency surgery
② Underlying severe systemic infection or hemodynamic instability.
③ Difficulty in communication due to the neurologic diseases such as dementia, stroke, seizure, etc.
④ Difficulty in communication due to the visual/hearing impairment, illiteracy, or foreigner.

Change of the perioperative EEG connectivity.

The EEG connectivity will be calculated after the surgery, using perioperative (before/during/after the surgery) EEG signals.

Confusion assessment method (Postoperative cognitive evaluation)

Right after the surgery, postoperative day1,2,3 and the day before the discharge of the patient.

Changes of the perioperative power spectral density of EEG

The power spectral density of EEG will be calculated after the surgery, using perioperative (before/during/after the surgery) EEG signals.

Perioperative burst-suppression ratio

The burst-suppression ratio will be calculated after the surgery, using perioperative (before/during/after the surgery) EEG signals.

Hospital Anxiety and Depression Scale (Pre-operative congnitive evaluation)

After the admission of the patient, before the surgery. The day before the discharge of the patient.

Korean-Montreal Cognitive Assessment (Pre-operative congnitive evaluation)

After the admission of the patient, before the surgery. The day before the discharge of the patient.