1. Department of Emergency Medicine, Beijing Friendship Hospital, Capital Medical University, 95 Yongan Road, Beijing 100050, China.
2. Department of critical care medicine, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China.
3. Department of Emergency Medicine, Beijing Chaoyang Hospital, Capital Medical University, 8 Workers' Stadium South Road, Beijing 100020, China.
4. Department of Emergency Medicine, China-Japan Friendship Hospital, Peking Union Medical College, Yinhua East Road, Chaoyang District, Beijing 100029, China.
5. Department of Emergency Medicine, Dongzhimen Hospital, Beijing University of Chinese Medicine, 5 Haiyangzang, Dongcheng District, Beijing 100700, China.
6. Department of Emergency Medicine, The Hospital of Shunyi District Beijing, China Medical University, 3 Guangming South Street, Shunyi District, Beijing 101300, China.