1. Department of Anesthesiology, School of Medicine, Shandong University, Jinan, Shandong 250012, P.R. China
2. Department of Operating Room, The Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, Shandong 264000, P.R. China
3. Department of Anesthesiology, Qingdao Hiser Medical Center, Qingdao, Shandong 266033, P.R. China
4. Department of Anesthesiology, The Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, Shandong 264000, P.R. China