1. Department of Thoracic Surgery, The First Hospital of Hebei Medical University, Shijiazhuang, Hebei 050031, P.R. China
2. Department of Clinical Nutrition, The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei 050011, P.R. China
3. Third Department of General Surgery, The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei 050011, P.R. China