1. Undergoing elective distal pancreatectomy for pancreatic cancer .
2. ASA statusⅠ-Ⅲ.
3. 18 years to 80 years （adults）.
4. Able to understand, communicate and sign an informed consent form.
You may not be if
1. Laparoscopic surgery.
2. Preoperative chemotherapy or radiotherapy.
3. Pregnancy.
4. Allergic to any drugs used during the study.
5. Long-term receiving β-blockers.
6. Complicated with chronic inflammatory diseases, autoimmune diseases, or long-term receiving glucocorticoids or other immunosuppressants before surgery.
7. Abnormal coagulation functions (platelet count prior to surgery \<100000/ μL , APTT value is more than the normal value, INR \> 1.3 or clopidogrel that cannot be discontinued 7 days prior to surgery).
8. Complicated with severe heart disease (NYHA classification \>3), severe renal insufficiency (serum creatinine \>1.8mg/dL or receiving renal replacement therapy), severe hepatic disease (Child-Pugh classification=C), diabetes (fasting blood glucose not in the range of 3.9-13.8 mmol/L ), or acute infectious diseases (WBC\>10000/μL) before surgery.
9. BMI \> 35.
10. All contraindications to epidural block.
11. Chronic opiate medication/drug abuse.
12. Complicated with severe mental illness, cognitive disorder or unable to collaborate during the study.
