1. Department of Anesthesiology, Affiliated Hospital of Qingdao University, Qingdao, Shandong Province, China
2. Department of Anesthesiology, Jining No. 1 People’s Hospital, Jining, Shandong Province, China
3. Department of Orthopedics, Jining No. 2 People’s Hospital, Jining, Shandong Province, China