Received: 19 January 2020
Accepted: 7 May 2020
First Online: 12 June 2020
Ethics approval and consent to participate
: This study was approved by the ethics committee of Peking Union Medical College Hospital, Beijing, China (Approval No. ZS-1422). Written informed consent was obtained from the next of kin of each patient.
: Informed consent was obtained from the next of kin.
: The authors declare that they have no competing interests.