1. Department of Pulmonary and Critical Care Medicine, Center of Respiratory Medicine, National Center for Respiratory Medicine, National Clinical Research Center for Respiratory Diseases, China-Japan Friendship Hospital , Beijing , China
2. Department of Respiratory and Critical Care Medicine, First Hospital of China Medical University , Shenyang , Liaoning Province , China
3. Department of Ultrasound, First Hospital of China Medical University , Shenyang , Liaoning Province , China
4. Department of Respiratory and Critical Care Medicine, Fourth Hospital of China Medical University , Shenyang , Liaoning Province , China