1. Department of General Surgery, The First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150001, P.R. China
2. Department of Intensive Care Unit, Qingdao Municipal Hospital, Qingdao, Shandong 266011, P.R. China
3. Department of Gastroenterology, Qingdao Municipal Hospital, Qingdao, Shandong 266011, P.R. China