1. Department of Respiratory Medicine, Navy General Hospital of The People's Liberation Army, Beijing 100037, P.R. China
2. Department of Neurology, The First Hospital of Changsha, Changsha, Hunan 430100, P.R. China
3. Cardiothoracic Surgery Intensive Care Unit, Anqing Municipal Hospital, Anqing, Anhui 246003, P.R. China