1. Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China
2. Beijing Jishuitan Hospital, the Fourth Medical College of Peking University, Beijing, China
3. The Fifth Medical Center, Chinese PLA General Hospital, Beijing, China
4. Beijing Chaoyang Integrative Medicine Emergency Medical Center, Beijing, China
5. Center of Pulmonary and Critical Care Medicine, Chinese PLA General Hospital, Beijing, China
6. Beijing Friendship Hospital of Capital Medical University, Beijing, China