1. Department of Respiratory and Critical Care Medicine, The Affiliated Changsha Hospital of Xiangya School of Medicine, Central South University, The First Hospital of Changsha, Changsha, Hunan 410000, P.R. China
2. Department of Nursing, The Fourth Hospital of Changsha, Changsha, Hunan 410000, P.R. China
3. Department of Respiratory and Critical Care Medicine, The Affiliated Changsha Hospital of Xiangya School of Medicine, Central South University, The First Hospital of Changsha, Changsha, Hunan 410000, P.R. China
4. Department of Respiratory Medicine, Yicheng People's Hospital of Shandong, Zaozhuang, Shandong 277300, P.R. China