1. Department of Geriatrics, Hebei General Hospital, No. 348, Heping West Road, Shijiazhuang, Hebei 050051, P.R. China
2. Department of Anesthesiology, Children’s Hospital of Hebei Province, No.133, Jianhua South Avenue, Yuhua District, Shijiazhuang, Hebei 050071, P.R. China
3. Department of Ultrasound, Hebei General Hospital, No.348, Heping West Road, Shijiazhuang, Hebei 050051, P.R. China