1. Department of Hepatobiliary and Pancreatic Surgery, the Affiliated Hospital of Qingdao University, Qingdao, Shandong Province, China
2. Department of Anesthesiology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
3. Department of General Surgery, Qilu Hospital, Shandong University, Jinan, Shandong Province, China
4. Department of General Surgery, the Affiliated Hospital of Qingdao University, Qingdao, Shandong Province, China