Somatostatin Prevent Post-operation Pancreatic Fistula in Intermediate Risk Patients After Pancreaticoduodenectomy

Patients in the Stilamin group will be continuous intravenous infusion with the somatostatin (Stilamin®) of 250μg/h, beginning within 3 hours (Visit 1) after the operation and lasting for 120 hours (each subject will receive the Stilamin of 30mg in total), and other postoperative conventional treatment protocol remain unchanged.