1. Department of Respiratory and Critical Care Medicine, Zhengzhou University People's Hospital, Henan Provincial People's Hospital, Zhengzhou, Henan 450003, China
2. Xinxiang Medical University, Xinxiang, Henan 453003, China
3. Department of Pneumology and Respiratory Care Medicine, Thoraxklinik and Translational Lung Research Center, University of Heidelberg, Heidelberg D-69126, Germany.