Endoscopic carbon dioxide insufflation tolerance test on the anal sphincter for anorectal hypofunction: a pilot and feasibility study.

Background: Anorectal function deteriorates with age. The diagnostic performance of the endoscopic pressure study integrated system (EPSIS), an endoscopic carbon dioxide (CO₂) insufflation stress test of the lower esophageal sphincter has been previously evaluated as a diagnostic tool for gastroesophageal reflux disease. We aimed to evaluate the applicability of EPSIS in improving anorectal function. We hypothesized that EPSIS can be applied to the diagnosis of lower gastrointestinal tract disorders.

Methods: This was a pilot, single-center, retrospective study using prospectively collected data between December 2021 and March 2022. It was designed to evaluate the differences in EPSIS rectal pressure measurements between older (≥80 years) and younger (<80 years) patients. At the end of the screening colonoscopy, the colonoscope was fixed in a retroflex position. When bowel movement was observed, CO₂ was insufflated to the point where gas leakage occurred through the anus. The measured maximum pressure was defined as EPSIS-rectal pressure max (EPSIS-RP max) and compared between the groups.

Results: Overall, 30 patients were included and examined. The median ages of the <80 and ≥80 years' groups were 53 (range: 27-79) and 82 (range: 80-94) years, respectively, with corresponding median measured EPSIS-RP max of 18.7 (range: 8.5-30.2) and 9.8 (range: 5.4-22.3) mmHg (P<0.001).

Conclusions: Measurement of maximum rectal pressure illustrates the age-related decline in physiological anorectal function. Future studies should consider a loading test using EPSIS to quantify the decline in anorectal function and use it as a routine tool for screening and adjunctive diagnosis of anorectal hypofunction.