1. Department of Emergency Medicine, The General Hospital of Western Theater Command, Chengdu, Sichuan 610083, P.R. China
2. School of Nursing, Lanzhou University, Lanzhou, Gansu 730010, P.R. China
3. Department of Hyperbaric Oxygenation Medicine, The General Hospital of Western Theater Command, Chengdu, Sichuan 610083, P.R. China
4. Center for Disease Control and Prevention, Western Theater Command, Lanzhou, Gansu 730020, P.R. China