1. Department of Critical Care Medicine, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
2. Department of Critical Care Medicine, Shangluo Central Hospital, Shangluo, Shaanxi 726000, P.R. China
3. Department of Pathology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China