1. Department of General Surgery, The Second Affiliated Hospital of Xi’an Jiaotong University, Xi’an, People’s Republic of China
2. Department of General Surgery, Yan’an People’s Hospital, Yan’an, People’s Republic of China
3. Department of Anesthesiology, The Second Affiliated Hospital of Xi’an Jiaotong University, Xi’an, People’s Republic of China
4. Department of Surgery, The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, People’s Republic of China