The evaluation of body surface gastric mapping for the assessment of patients with gastrointestinal symptoms in New Zealand

Body Surface Gastric Mapping (BSGM) will be performed on all participants who enrol in this study. BSGM is a novel medical device for non-invasively assessing gastric motility, using a high-density array of 64 electrodes mounted on the epigastric skin. This BSGM provides a more complete understanding of the origin and propagation of human gastric slow-wave activity non-invasively, such as frequency and pattern, in high spatiotemporal detail. The system also includes an App for tracking patient-reported symptoms throughout the test. The study involves a simple test, "like an ECG for the gut" that will be conducted for a period from 90 minutes to five hours. The study is painless and non-invasive, although participants must keep still. Participants will be asked to fast (not eat or drink anything including tea and coffee) overnight before their test (for at least 8 hours), and asked not to smoke or vape in the morning of their test. They may also be asked to refrain from taking some medications for 48 hours before their test. These medications include: drugs that affect gastric emptying (metoclopramide, domperidone, erythromycin), antispasmodics, pain medications which contain opiates (codeine, oxynorm, morphine, and tramadol), or sedatives. This is because these medications affect normal stomach actions. Upon arrival, participants will be required to fill out questionnaires about their medical history, symptoms, and gastrointestinal-related quality of life. Participants will also be asked to fill out questionnaires to assess anxiety, depression, stress and illness perceptions, since these factors have been found to be related to some GI problems. These questionnaires will be optional and will take approximately 15 minutes. The BSGM recording will then be set-up: A guide will be used to locate the array in a personalised manner. A portable ultrasound may be used to verify this positioning system is accurate. Excess hair will be removed and participant’s skin will be prepped using NuPrep, which reduces skin impedance for enhanced test results. A 64-channel electrode array (28 cm x 17 cm) will be non-invasively placed over the abdominal skin and connected to a portable data logger by a trained research assistant. For some participants, the sensor array will also be connected to a second clinical recording device, if part of another study taking place at the same time (which will have separate ethical approval and trial registration). For some participants, a second array will be placed over the lower abdomen in order to measure their colonic activity alongside their stomach activity. This will help differentiate signals from the stomach and colon. Participants will be given a smartphone or tablet and be instructed on how to log symptom information throughout the study. After around 30 minutes of baseline BSGM data is captured, the participant will be asked to consume a standardised meal of approximately 200-500 kCal. Suitable dietary options will be available for diabetics, people with dairy or gluten sensitivities, or people who are vegan. The recording will continue between 60 to 240 minutes after the meal. A normal test has a 240minute post-meal recording; however, this can be shortened if the participant is unable to sit still for that amount of time. During this time the participant will be asked to sit in a reclined position and limit movement, talking, laughing or sleeping. Once the recording has been finished, the sensor array(s) will be removed from the abdomen and disposed of.