1. Department of Respiratory Medicine, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, P.R. China
2. Department of Respiratory Medicine, The Sixth People's Hospital of Nantong, Nantong, Jiangsu 226001, P.R. China
3. Department of Rehabilitation Medicine, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, P.R. China