Transcutaneous auricular vagus nerve stimulation combined with ciprofol for sedation in patients undergoing same-session bidirectional endoscopy: a randomized, double-blind, placebo-controlled, three-arm non-inferiority trial protocol

BACKGROUND: Transcutaneous auricular vagus nerve stimulation (taVNS) provides targeted modulation of the autonomic nervous system and descending pain pathways, exerting analgesic potential. However, high-quality evidence remains insufficient to determine whether taVNS can effectively replace opioids in sedation regimens for same-session bidirectional endoscopy while maintaining the quality of early postoperative recovery. DISCUSSION: This study is a single-center, prospective, randomized, double-blind, placebo-controlled, three-arm non-inferiority trial. A total of 181 patients scheduled for painless same-session bidirectional endoscopy will be enrolled and randomly assigned using dynamic block randomization to one of three groups: Group S (sufentanil 0.1 µg/kg plus sham taVNS), Group T (normal saline plus active taVNS), and Group P (normal saline plus sham taVNS). All participants will receive ciprofol for sedation induction and maintenance. The primary outcome will be the quality of recovery at 24 h postoperatively, assessed using the 15-item Quality of Recovery scale (QoR-15), with a predefined non-inferiority margin (δ) of 6 points, which corresponds to the minimal clinically important difference of the QoR-15 scale. Secondary outcomes will include perioperative adverse events (pre-, intra-, and postoperative, including taVNS-related events), QoR-15 score at 1 h postoperatively, procedural and recovery efficiency indices, sedative dosage, and patient and endoscopist satisfaction scores. Blinding effectiveness will be assessed in all participants, and statistical analyses will follow the modified intention-to-treat principle. CONCLUSION: This study protocol will rigorously assess the effectiveness and safety of taVNS as an alternative to opioid analgesics for sedation during same-session bidirectional endoscopy using, to our knowledge, the first three-arm design.Trial registration: Chinese Clinical Trial Registry (ChiCTR2600117962).