Patients undergoing elective orthopedics, urology, and general surgery will be included and randomly allocated to TEAS group or control group . After routine anesthesia induction and tracheal intubation, patients in TEAS group will receive electrical stimulation of acupoints at Neiguan and Shenmen points. For patients in the control group, the electrodes will be only attached to the corresponding sites, with no TEAS electrical stimulation given during the operation. The primary outcome is the incidence of POCD at Day 7 after surgery. The secondary outcomes include the incidence of POD during post-operative days 1-7, the incidence of POCD at Day 30 after surgery, and the serum levels of cytokines, including IL-1β、IL-6、TNF-α、MMP9 on Day 1 after surgery.

This study will enroll 110 patients who are older than 60 years old and will have elective orthopedics, urology, or general surgeries under general anesthesia. Patients will be randomly assigned to TEAS group and control group. After routine anesthesia induction and tracheal intubation, patients in TEAS group will receive electrical stimulation of acupoints at Neiguan and Shenmen points for 30min every hour. In other words, the patients will receive TEAS stimulation for 30min, then no stimulation for 30min, then stimulation for another 30min, etc, until the end of the surgery. For patients in the control group, the electrodes will be only attached to the corresponding sites, with no TEAS electrical stimulation given during the operation. The primary outcome is the incidence of POCD at Day 7 after surgery. The secondary outcomes include the incidence of POD during post-operative days 1-7, the incidence of POCD at Day 30 after surgery, and the serum levels of cytokines, including IL-1β、IL-6、TNF-α、MMP9 on Day 1 after surgery.

Inclusion Criteria:

1. ≧ 60 years old;
2. communicate normally；
3. ASA Physical Status 1-2;
4. Patients will have elective orthopedics, urology or general surgeries under general anesthesia;
5. With an estimated surgery time of more than 2h;
6. Agree to participate the trial.

Exclusion Criteria:

1. Patients with brain diseases or history of brain diseases;
2. Preoperative diagnosis of cognitive impairment by subtle mental state (MMSE) less than 24 points;
3. Patients with history of neurological and psychological disorders including AD, stroke, and psychosis;
4. Severe hearing or visual impairment, illiteracy;
5. preoperative systolic blood pressure >190mmHg, or diastolic blood pressure >100mmHg;
6. Disagree to participate in this research;
7. Have used other medical electronic devices.