Vagus nerve stimulation to improve bowel function after surgery

INTERVENTION: A feasibility RCT will be performed at two research sites. This will involve patients randomly assigned to four groups: 1. Pre‐operative active stimulation and post‐operative sham stimulation 2. Pre‐operative sham stimulation and post‐operative active stimulation 3. Pre‐operative sham stimulation and post‐operative sham stimulation 4. Pre‐operative active stimulation and post‐operative active stimulation Patients will be approached about the study at their routine outpatient appointment by members of the clinical team. Verbal and written information will be provided and patients will be invited to take this home. With permission, they will be contacted 24 hours later to determine their decision to participate. They will be permitted to confirm their interest earlier than 24 hours if they wish, and their right to withdraw at any time will be emphasised strongly. Patients who confirm their interest (via telephone or at the time of approach) and satisfy all eligibility criteria will be invited to provide informed, written consent. Randomisation will take place immediately after consent via a 24‐hour online randomisation service. During the information‐giving and consent processes, patients treated at the lead research site will be invited to enrol in several optional sub‐studies. These are optional and not essential for participation in the main trial. 1. Inflammatory sub‐study: this will involve a series of four blood tests and two abdominal fluid samples during surgery. Information about this sub‐study will be included on the main trial information sheet and optional consent will be confirmed on the main trial consent form. Participation will be limited to the main study site, and no pre‐specified limit on the number of participants will be set. Additional sub‐study eligibility criteria will apply. 2. Bowel motility sub‐st CONDITION: Colorectal Surgery ; Surgery ; Colorectal Surgery INCLUSION CRITERIA: 1. Aged > = 18 years 2. Able to provide written informed consent 3. Planned to undergo elective, minimally‐invasive (laparoscopic or robotic), colorectal surgery PRIMARY OUTCOME: ; As a feasibility study, the study does not have a primary defined outcome. Instead, it has a series of outcomes to; confirm or refute the feasibility of a definite RCT.; ; Measured at or up to 30 days after surgery:; Outcomes to inform progression:; 1. Proportion of eligible patients identified from screening logs; 2. Number of eligible patients randomised (per month), including reasons for approach failure; 3. Adequacy of participant blinding according to a blinding poll (Bang Blinding Index); 4. Compliance to the study treatment schedule according to participant‐reported diaries; 5. Proportion of randomised participants lost to follow up; 6. Incidence of serious and unexpected serious complications; ; Outcomes to explore clinical variability; 1. Time to first passage of flatus; 2. Time to first passage of stool; 3. Time to first oral tolerance (tolerance of solid diet in the absence of vomiting for 12 hours); 4. Time to GI‐2 (a composite of time to first oral tolerance and passage of first stool); SECONDARY OUTCOME: ; Outcomes for the optional sub‐studies (lead site only) are described below.; ; Inflammatory response sub‐study:; 1. Serum interleukin (IL) 1‐beta, IL6, and tumour necrosis factor (TNF)‐alpha at time points:; 1.1. Morning of surgery – after pre‐operative stimulation schedule/prior to surgery; 1.2. 2‐4 hours after start of surgery – measured from time of "knife‐to‐skin"; 1.3. 24 hours after start of surgery – measured from time of "knife‐to‐skin"; 1.4. 72 hours after start of surgery – measured from time of "knife‐to‐skin"; ; 2. Peritoneal fluid IL‐6, IL1‐beta, and TNF alpha at time points:; 2.1. Start of surgery – estimated 0‐30 minutes after "knife‐to‐skin"; 2.2. End of surgery – estimated 2‐4 hours after "knife‐to‐skin"; ; Small bowel motility sub‐study:; 1. Small bowel motility measured by assigning a validated GIQuantâ„¢ score to MR enterography scans;