1. Department of Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi 530021, P.R. China
2. Department of Gastrointestinal Surgery, The People's Hospital of Guangxi Zhuang Autonomous Region, Guangxi 530021, P.R. China
3. Department of Anesthesiology, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi 530021, P.R. China