Transcutaneous vagal nerve stimulation & postoperative bowel function

INTERVENTION: Participants self‐administer a hand held, non‐invasive, vagal nerve stimulator device before and and after surgery. Half of patients will have a functioning device and the other half will have a “dummy” device which looks and feels the same but does not produce nerve stimulation. This will allow the effect of the functioning device to be compared. Bowel function is assessed daily, as well as postoperative assessments of systemic cytokine response and small bowel motility. CONDITION: Specialty: Surgery, Primary sub‐specialty: Colorectal Surgery; UKCRC code/ Disease: Oral and Gastrointestinal/ Other diseases of the digestive system ; Digestive System ; Postoperative ileus (POI) PRIMARY OUTCOME: Time taken to first bowel movement is measured according to daily clinical enquiry. SECONDARY OUTCOME: 1. Time to first flatus is measured according to daily clinical enquiry; 2. Time to oral tolerance (solid food in the absence of vomiting) is measured according to daily clinical enquiry; 3. Serum cytokines IL1b, IL6 & TNFa are measured by blood draw on postoperative days 1 and 3; 4. Small bowel motility is measured using a quantitative score generated by Magnetic resonance enterography (MRE) studies INCLUSION CRITERIA: 1. Aged greater than 17 years 2. Able to provide written informed consent 3. Able to use the device and comply with study procedures 4. Confirmed diagnosis of colorectal cancer via radiological or histological modalities 5. Undergoing elective laparoscopic colorectal resection