1 Shandong University, Cheeloo College of Medicine, Qilu Hospital (Qingdao), Department of Anesthesiology, Qingdao, China.
2 Shandong University, Cheeloo College of Medicine, Qilu Hospital (Qingdao), Department of Radiology, Qingdao, China.
3 Shandong University, Cheeloo College of Medicine, Qilu Hospital (Qingdao), Department of Anesthesiology, Qingdao, China. Electronic address: hope6968@hotmail.com.
4 Shandong University, Cheeloo College of Medicine, Qilu Hospital (Qingdao), Department of Anesthesiology, Qingdao, China. Electronic address: weipenghuihui@sina.com.