Effect of water soluble defoamer on colonoscopic bubble score in adult patients undergoing colonoscopy

This is a prospective, open-labelled pilot study of adult patients undergoing colonoscopy at University Hospital Geelong. Patients will be recruited for the study at the time of booking for their colonoscopy, and informed consent will be obtained by the doctor arranging the colonoscopy. All patients will have been booked for the procedure on clinical grounds, they will NOT undergo the procedure purely for the purposes of the study. Patients will undergo pre- operative bowel preparation, anaesthesia, and colonoscopy according to the standard current protocols. If the endoscopists view is obscured by bubbles, propylene glycol solution will be instilled via the working channel of the colonoscope. This will be instilled at a concentration of 0.1g/ml in 10ml flushes until adequate views are obtained, or up to a maximum of 60ml. This would give a maximum dose of 6g, which is approximately the amount that could be added to one orange under Australian food safety regulations. The number of flushes delivered to obtain clear views will be recorded. The extent of bubbles will be recorded using a previously published [Mallard et al 2023] endoscopic bubble scale (Grade 0 [minimal or no bubbles]; 1 [bubbles covering <50% of the luminal circumference]; 2 [bubbles covering >50% the lumen circumference]; 3 [bubbles filling the entire lumen]) before flushing and within 30 seconds after flushing. If adequate views cannot be obtained after flushing with 60ml propylene glycol, further flushing will be done as needed using cimethicone at the endoscopists discretion in keeping with standard clinical practice.