1. Department of Emergency, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China.
2. Beijing Key Laboratory of Cardiopulmonary Cerebral Resuscitation, Beijing, China.
3. Department of Emergency, Beijing Fu-Xing Hospital, Capital Medical University, Beijing, China.
4. Department of Emergency, Beijing Tongren Hospital, Capital Medical University, Beijing, China.
5. Department of Emergency, Beijing Friendship Hospital, Capital Medical University, Beijing, China.