Non-invasive vagus nerve stimulation to reduce postoperative ileus: Feasibility study

Background

Postoperative ileus is a debilitating complication after abdominal surgery. Numerous treatments to curtail its impact on patients and healthcare systems have been explored but few have led to clinically meaningful improvements in care. Electrical stimulation of the vagus nerve using a non-invasive and self-administered device has emerged as a new candidate treatment. This work aimed to explore the feasibility of a definitive randomised evaluation in patients undergoing major colorectal surgery.

Method

Firstly, a scoping review was performed, exploring the role of the vagus nerve in maintaining intestinal homeostasis and its role in reducing ileus in pre-clinical and early clinical studies. Secondly, a randomised, sham-controlled, feasibility trial was undertaken, examining the feasibility of recruitment, treatment compliance, participant blinding, and data completeness for a future trial. This was supplemented by semistructured interviews with patients and healthcare professionals, exploring barriers and enablers of feasibility. Finally, a core outcome set for postoperative ileus was developed through international, multi-stakeholder consensus.

Findings

In existing pre-clinical studies, vagus nerve stimulation was shown to suppress intestinal inflammation and attenuate postoperative intestinal dysfunction via a cholinergic anti-inflammatory reflex. Early clinical studies showed that this was directly translatable to humans. The feasibility trial showed that participant recruitment, compliance to self-administration, and the collection of clinically-relevant endpoint data were readily feasible. In contrast, unblinding of participants was common, mainly due to expectations regarding the sensation and user-experience of the device. The interview findings identified a lack of confidence and a steep learning curve as modifiable barriers to fidelity. A core outcome set comprising twenty outcomes was ratified for use in future research.

Conclusion

A definitive randomised evaluation of non-invasive, vagus nerve stimulation may be feasible after modification. Targets for change include refinement to participant blinding procedures and confirmation of the fidelity of self-administration. A dedicated assessment of clinical efficacy is required prior to progressing to definitive assessments of clinical and cost effectiveness.