The Efficacy and Safety of S-ketamine in Elective Cesarean Section

Inclusion Criteria: 1. ASA II; 2. Parturients voluntarily sign an informed consent form, fully understands the purpose and significance of the study, and voluntarily abides by the clinical study procedure; 3. Subjects who plan to be elected to undergo cesarean section under continuous combined spinal-epidural anesthesia; 4. Age 18 to 40 years; 5. The expected duration of surgery was less than 2h; 6. Prenatal body mass index (BMI) was less than 35kg/m2。 Exclusion Criteria: 1. Parturients with contraindications to continuous combined spinal-epidural anesthesia (such as history of central nervous system infection, spinal cord or spinal canal disease or surgery history, systemic infection, skin or soft tissue infection at the puncture site, coagulation dysfunction); 2. Those who have a history of stroke, cognitive dysfunction, and epilepsy; 3. Patients with a history of myocardial infarction, angina pectoris, or a serious arrhythmia such as second-degree and above-degree atrioventricular block within 6 months before screening; 4. Pregnancy with other diseases (malignant tumors, hypertension during pregnancy, abnormal thyroid function, etc.); 5. In the non-oxygen state, the peripheral blood oxygen saturation (SpO2) \<92%; 6. Subjects whose prolactin is greater than the upper limit of normal during the screening period; 7. Alanine aminotransferase (ALT), aspartate aminotransferase (AST), glutamine transferase (GGT)\> 1.5 times than the normal value, and total bilirubin is higher than the upper limit of normal value, and blood creatinine (Cr)\>1.2 times than the upper limit of normal value; 8. The effect of combined spinal-epidural anesthesia is not good, and other anesthetics are needed; 9. People with a history of allergies to various foods and drugs; 10. Continuous taking for any reason within 3 months before the screening, including but not limited to: ketamine, non-steroidal anti-inflammatory drugs (aspirin, acetaminophen, indomethacin, diclofenac, ibuprofen, parecoxib) Sodium, etc.), alpha adrenergic receptor agonists (dexmedetomidine hydrochloride, clonidine, etc.), glucocorticoids (dexamethasone hydrochloride, hydrocortisone, methylprednisolone, etc.), antiepileptic ( Carbamazepine, sodium valproate, etc.), sedation (diazepam, estazolam, midazolam, alprazolam, barbital, phenobarbital and chloral hydrate, etc.), Chinese herbal medicine or Chinese patent medicine with pain and sedative effect; 11. There is a history of drug abuse and/or alcohol abuse within 1 year before the screening; 12. Participated in other drug or device trials within 3 months before the screening; 13. Subjects judged by the investigator to be unsuitable to participate in this clinical study.