The Effect of Liposomal Bupivacaine Erector Spinae Plane Block

Inclusion Criteria: 1. Patients scheduled for elective open upper abdominal surgery, including open liver, gastric and pancreatic surgery. 2. Patients receiving general anesthesia with tracheal intubation. 3. Aged from 18 to 80 years old. 4. Patients with American Society of Anesthesiologists (ASA) physical status class Ⅰ-Ⅲ. 5. Patients who can understand the trial content, are willing to strictly follow the clinical research protocol and complete the trial, and voluntarily sign the informed consent form. Exclusion Criteria: 1. Pregnant or lactating women. 2. Patients complicated with severe primary diseases of the lung, liver, kidney, cardiovascular system and hematopoietic system. 3. Bleeding tendency or coagulation dysfunction, defined as international normalized ratio (INR) ≥ 1.4, activated partial thromboplastin time \> 38 s, or platelet count \< 80×10⁹/L. 4. Patients with aggravated cardiac diseases (complex congenital heart disease, heart failure and valvular disease) or pulmonary insufficiency. 5. Skin infection at the puncture site for erector spinae plane block (ESPB). 6. Previous history of neurological or psychiatric diseases, with inability to read, understand and communicate. 7. Current obstructive or restrictive pulmonary disease. 8. Patients with BMI greater than 30 kg/m². 9. Drug abuse, long-term regular use of analgesics, or allergy to the study drugs. 10. Patients who refuse to provide informed consent. 11. Those enrolled in other randomized controlled trials simultaneously or with other conditions unsuitable for participation in this trial.