Clinical Research Directory

Inclusion Criteria: 1. voluntary informed consent; 2. age older than 18 years 3. abdominal surgery under elective general anesthesia Exclusion Criteria: 1. Patients taking long-term analgesics (including opioids, non-steroids, etc.) 2. Patients with preoperative chronic pain 3. Have participated in clinical studies in other projects within 3 months prior to signing the informed consent form 4. subjects not considered by the investigator 5. subjects refused to participate in the study