O126: Non-invasive vagus nerve stimulation to reduce ileus after colorectal surgery: randomised feasibility trial and efficacy assessment

Abstract Objective Ileus is characterised by intestinal dysmotility after surgery. In preclinical models, vagus nerve stimulation reduces intestinal inflammation, preventing smooth muscle dysfunction and accelerating the return of gut function. This study explored the efficacy and feasibility of a definitive trial and implementation of non-invasive, electrical, vagus nerve stimulation (nVNS). Design A participant-blinded, multi-centre, feasibility trial of self-administered nVNS was performed. Patients undergoing colorectal surgery were randomised to four groups of pre- and post-operative treatment (A: nVNS/nVNS; B: nVNS/Sham; C: Sham/nVNS; D: Sham/Sham). Feasibility outcomes were participant recruitment, compliance, and blinding. Clinical outcomes were intestinal function and adverse events. Interviews with patients and clinicians explored barriers to feasibility and implementation. In an independent cohort, the effects of nVNS on serum IL-1b, IL-6, and TNFa were quantified at baseline, 24-hours, and 72-hours after surgery. Results Ninety-seven out of 125 (77.6%) eligible patients took part. The median compliance was 19 out of 20 stimulations (IQR: 17-20). The median time to pass stool was 4 (3-5), 3 (2-4), 2.5 (2-3.5), and 3 (2-4) days for groups A-D, respectively. The incidence of adverse events was similar across groups. Trends toward reduced pro-inflammatory mediators were observed after nVNS. Interviews with patients (n=19) demonstrated their motivation to contribute actively to their recovery and interviews with clinicians (n=10) revealed strong reciprocal support. Conclusion This study confirms the safety, feasibility, and support for nVNS after surgery. Research on nVNS should progress from its current focus on pre-clinical models to powered, dedicated assessments of clinical effectiveness.