1. Department of Pulmonary and Critical Care Medicine, Zibo First Hospital, Zibo, Shandong 255200, P.R. China
2. Department of Oncology, Zibo First Hospital, Zibo, Shandong 255200, P.R. China
3. Department of Clinical Medicine, Jining Medical College, Jining, Shandong 272067, P.R. China
4. Department of Pulmonary and Critical Care Medicine, Central Hospital Affiliated to Shandong First Medical University, Jinan, Shandong 250013, P.R. China