Efficacy and Safety of S-ketamine in Elderly Patients Undergoing Non-cardiac Surgery: a RCT（ESSENCE）

Inclusion Criteria:

* 1\) Aged \> 65 years old, no gender limitation;
* 2\) patients undergoing elective thoracic, abdominal and orthopedic surgery;
* 3\) ASA score is Class I-Class \~III;
* 4\) 18 kg/ m2\<BMI\<30kg/m2；
* 5\) The operation time is estimated to be 2 h-4 h;
* 6\) Know clearly and voluntarily participate in this study, and sign informed consent form by oneself.

Exclusion Criteria:

* 1\) patients with severe chronic pain;
* 2\) Anemia or thrombocytopenia, Hb \< 90 g/L, PLT \< 80 × 109/L;
* 3\) Severe liver dysfunction, AST and/or ALT≥2.5×ULN, and TBIL ≥ 1.5 × ULN;
* 4\) severe renal dysfunction, blood creatinine is greater than the upper limit of normal;
* 5\) Severe cardiovascular history (such as myocardial ischemia, heart failure and arrhythmia); Angina pectoris (unstable angina pectoris) caused by insufficient blood supply to the coronary vessels of the heart, or myocardial infarction in the past 6 months; QT interval prolongation (≥460ms in males and ≥ 470 ms in females);
* 6\) Patients with hypertension whose blood pressure is not satisfactorily controlled by antihypertensive drugs (systolic blood pressure in sitting position during screening stage ≥180 mmHg, and/or diastolic blood pressure during screening stage ≥ 100 mmHg);
* 7\) Patients with craniocerebral injury, possible intracranial hypertension, cerebral aneurysm, cerebrovascular accident history and central nervous system disease history;
* 8\) patients with glaucoma or serious increase in intraocular pressure risk;
* 9\) patients with mental system diseases (schizophrenia, mania, bipolar disorder, mental disorder, etc.) and drug history and cognitive dysfunction; History of cognitive psychiatric disorders such as postoperative delirium; Pregnant or lactating women;
* 10\) high risk surgery, is expected to enter the ICU after surgery;
* 11\) to moxa ketamine hydrochloride and its drug components allergy or taboo;
* 12\) Being a subject and having participated in clinical trials for other drugs in the past three months;
* 13\) There is communication disorder;
* 14\) Patients considered by the investigator to be ineligible for participation in this trial.