Study design and participants
This dual-center, randomized, placebo-controlled study was conducted at Beijing Tiantan Hospital, Capital Medical University, and Beijing Daxing People’s Hospital between August 14th, 2020, and September 30th, 2021. This study was approved by the China Ethics Committee of Registering Clinical Trials (Registration number: ChiECRCT20200200) and registered at Clinicaltrials.gov (NCT04477733, 20/07/2020)) in July 2020. All patients or their legal representatives provided written informed consent. The study followed the Consolidated Standards of Reporting Trials (CONSORT) guidelines.We recruited adult patients aged 18 to 65 with an American Society of Anesthesiologists physical status from I to III who underwent colonoscopy or gastroscopy. The exclusion criteria included patients with a body mass index > 30 kg/m