Funding for this research was provided by:
National Natural Science Foundation of China (61701540)
Received: 9 April 2020
Accepted: 24 July 2020
First Online: 30 July 2020
Ethics approval and consent to participate
: The research has been approved by the Medical Ethics Committee of Chinese PLA General Hospital for clinical research (No. 2018-176-01). Each subject signed the informed consent.
: When bowel sounds were obtained from patients, prior approval was obtained for future use of these records.
: The authors declare that they have no competing interests.