1. Department of Emergency, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing 100730, P.R. China
2. Department of Emergency, The Second Hospital of Hebei Medical University, Shijiazhuang, Hebei 050000, P.R. China
3. Department of Emergency, The Second People's Hospital of Guiyang, Guiyang, Guizhou 550023, P.R. China