Methods
MAY
This prospective, single-center, parallel-group, assessor-blinded, randomized controlled trial was conducted in Beijing Tiantan Hospital, Capital Medical University, from August 16, 2021 to August 30, 2022 and was approved by the Institutional Review Board of Beijing Tiantan Hospital at May, 16 2021 (KY2021-082-02). The study was registered on clinicaltrials.gov.cn on 29/10/2020 (trial registration number: NCT04608682). Before randomization, written informed consent was obtained from all participants during preoperative evaluation. The trial protocol has already been published [Eligible candidates were patients from 18 to 65 years old undergoing thoracic or lumbar spinal surgery with TceMEPs monitoring and American Society of Anesthesiologists (ASA) physical status I to II. The exclusion criteria included BMI ≥ 35 kg/m