High Volume Simethicone VCE Clinical Trial

BACKGROUND:

While VCE has become an important diagnostic tool for clinical practice, optimal preparation for VCE has yet to be determined.(13) The European Society of Gastrointestinal Endoscopy recommends bowel preparation but does not provide further details.(2) The Canadian Association of Gastroenterology, American Society of Gastrointestinal Endoscopy, American College of Gastroenterology, and American Gastroenterological Association make no specific recommendation. Many studies have addressed this knowledge gap, testing various regimens of purgatives.(14-18) A meta-analysis found that polyethylene glycol provided adequate visual quality in 68% of patients compared to 48% with fasting alone, while diagnostic yield climbed from 36% to 46%.(4) In contrast, oral preparation for colonoscopy produces adequate visualization in greater than 90% of patients.(19)

Intraluminal debris, bile, and air bubbles impair the visibility of small bowel mucosa during VCE. Simethicone, an anti-foaming agent, has been used with mixed success to improve image quality. Three studies investigated the addition of simethicone (30 mg, 600 mg, and 800 mg) to overnight fast, PEG, or mannitol demonstrated improvement in visualization with high preparation scores favouring the addition of simethicone.(7-9) In contrast, Wei and colleagues (10) compared simethicone (300 mg) + PEG with PEG alone and found that although simethicone improved visualization, adequate visualization was achieved in only 63% of patients. Similarly, Ge et al. (11) compared simethicone (300 mg) against fasting alone and found improvement in visualization with simethicone but this was limited to the proximal half of the small bowel and adequate visualization was limited to 55% of cases. Lastly, Rosa et al. (12) compared simethicone (100 mg) + PEG with PEG alone and did not find a difference in visualization score.

A potential reason for inconsistent improvement in small bowel visualization may be due to an inadequate volume of simethicone being delivered into the small bowel, especially the distal portions. Prior volumes of simethicone were small (<200 ml) and may have pooled in the stomach and become diluted by gastric juices before being delivered into the duodenum. Our hypothesis is that high volume simethicone may overcome this problem and improve small bowel cleansing to facilitate improved visualization during VCE.

STUDY DESIGN:

This is a double blind randomized clinical trial evaluating high volume simethicone (750 ml at 1.5 mg/ml) versus standard volume simethicone (200 ml at 1.5 mg/ml) for CE. Randomization will be performed in blocks of varying sizes through a web based interface, Research Electronic Data Capture (REDCap), to ensure concealed allocation. Patients, physicians, and outcome assessors will be blinded to randomization allocation.

INTERVENTION:

All patients will take a standard small bowel preparation consisting of the following starting the day before the procedure: clear fluids starting at lunch, two liters of PEG at 8 PM, and fasting starting at midnight. Patients arrive in the endoscopy unit at 6:45 AM the following morning. Randomization is performed via REDCap and simethicone given as follows: those randomized to high volume simethicone will drink a 750 ml solution (1125 mg simethicone diluted in 750 ml of water, 1.5 mg/ml) and those randomized to standard volume simethicone will drink a 200 ml solution (300 mg simethicone diluted in 200 ml of water, 1.5 mg/ml) in identical non-transparent lidded cups sealed with tamper tape prepared by the hospital's Clinical Trials Pharmacy and administered to the patient by the research nurse. Regardless of randomization results, the solution will be consumed over a 5 minute period and the patient instructed to resume fasting for 30 minutes before swallowing the capsule. Adherence will be assessed by collection of the cups after ingestion.

After swallowing the capsule, the patient is discharged from the endoscopy unit, encouraged to remain active for the day, allowed to have clear fluids in 2 hours, a light meal in 4 hours, and to return the CE recorder to the endoscopy unit at 5 PM. Once the CE recorder is returned, the patient is discharged from the endoscopy unit and has completed the study. Subjects will be called by the study nurse 7 days later to assess for adverse events.

CE will be performed with the Given Imaging SB3 capsule and reviewed with the accompanying software, RAPID v8.3. Videos will be reviewed in a blinded fashion without knowledge of randomization results using the Park score.(41)