Table 1.

Research settings

01	Department of respiratory medicine, Chinese People’s Liberation Army General Hospital
02	Department of emergency, Chinese People’s Liberation Army General Hospital
03	Department of respiratory medicine, First Affiliated Hospital of Chinese People’s Liberation Army General Hospital
04	Department of emergency, First Affiliated Hospital of Chinese People’s Liberation Army General Hospital
05	Chinese People’s Liberation Army General Hospital of Rocket Forces
06	Navy General Hospital of Chinese People’s Liberation Army
07	Beijing Shi Ji Tan Hospital, Capital Medical University
08	Tianjin First Center Hospital
09	The Fourth Affiliated Hospital of China Medical University