Ningxia Medical University, Gongli Hospital of Shanghai Pudong New Area Training Base, 200135 Shanghai, P.R, China. Department of Pain Medicine, Peking University Third Hospital, 100191 Beijing, China. Department of Anesthesiology, Shanghai Gongli Hospital, the Naval Military Medical University, 200135 Shanghai, P. R, China. Ningxia Medical University, Gongli Hospital of Shanghai Pudong New Area Training Base, 200135 Shanghai, P.R, China; Department of Anesthesiology, Shanghai Gongli Hospital, the Naval Military Medical University, 200135 Shanghai, P. R, China.