Funding for this research was provided by:
Chongqing Health Commission Projects (2016MSXM157, 2017MSXM019)
Respiratory Prevention and Treatment Center of Shanxi Provincial Government (2016HXKF09)
Shanxi Province Key Program Fund (2017SF-256)
Received: 13 June 2019
Accepted: 21 September 2019
First Online: 30 September 2019
Ethics approval and consent to participate
: The Institutional Review Board of the First Affiliated Hospital of Chongqing Medical University approved the study. Informed consent was obtained from patients or their family members.
: All authors have reviewed and approved the manuscript for publication.
: The authors declare that they have no competing interests.