Transcutaneous auricular vagus nerve stimulation for the prevention of sufentanil-induced cough and postoperative sore throat: a randomised, double-blind, sham-controlled clinical trial protocol

Background Sufentanil-induced cough (SIC) and postoperative sore throat (POST) are common during general anaesthesia involving tracheal intubation, with reported incidences of approximately 35% and 62%, respectively. Although generally mild and self-limiting, both complications can adversely affect patient satisfaction and postoperative recovery. Current pharmacological prophylactic strategies are associated with risks including dizziness, respiratory depression and metabolic disturbances, and are supported by limited high-quality evidence. Transcutaneous auricular vagus nerve stimulation (taVNS) is a non-invasive neuromodulatory technique that may activate the endogenous descending analgesic system through the auricle–brain axis, thereby rapidly increasing the mechanical pain threshold and producing sustained analgesic effects. However, robust clinical evidence supporting its role in preventing anaesthesia-related perioperative complications remains lacking. This trial aims to evaluate whether taVNS reduces the incidence and severity of SIC and POST. Methods/design In this single-centre, prospective, double-blind, sham-controlled trial, 268 patients (aged 18–65, ASA I–III) will be randomised 1:1 to receive taVNS or active sham stimulation. Both groups will undergo the same initial current titration to individual maximum tolerated level. Thereafter, the taVNS group will receive 30 min of effective stimulation (30 s on/off), whereas the sham group will receive sham-controlled stimulation (current ramped down to zero over 15 s and then off). All patients will undergo standardised anaesthetic induction and maintenance. The primary outcome is the incidence of SIC, with POST as a key secondary outcome. Secondary outcomes include the severity of SIC and POST, haemodynamic fluctuations, adverse events and patient satisfaction. Analyses will follow the intention-to-treat principle, with modified intention-to-treat as a sensitivity analysis. Discussion SIC and POST remain common perioperative complications that may adversely affect postoperative recovery and patient satisfaction, yet high-quality evidence supporting effective prophylactic strategies remains limited. This trial is designed to provide robust, double-blind, sham-controlled evidence regarding the efficacy of taVNS in reducing both SIC and POST. If proven effective, taVNS may represent a safe, non-invasive, and promising non-pharmacological alternative to pharmacological prophylaxis against these complications. Clinical Trial Registration https://www.chictr.org.cn/showproj.html?proj=310119 , identifier: ChiCTR2600119305.