1 Department of Pharmacy, The Ninth People's Hospital of Qingdao, 2 Chaocheng Road, Qingdao 266002, China.
2 Department of Anesthesiology, The Affiliated Hospital of Qingdao University, 16 Jiangsu Road, Qingdao 276000, China.
3 Department of Anesthesiology, The Affiliated Hospital of Qingdao University, 16 Jiangsu Road, Qingdao 276000, China. Electronic address: liangzi66@hotmail.com.