Fasting pyloric diameter and distensibility by functional endoluminal imaging probe in unsedated healthy volunteers

Background: Recent studies with functional endoluminal imaging probe (EndoFLIP^®) measure physiologic characteristics of the pylorus. EndoFLIP^® has the potential to select optimal candidates for gastric peroral endoscopic myotomy (G-POEM). Normative values of the pylorus using EndoFLIP^® have not been established. Methods: Twenty-four healthy volunteers (20–56 years old; 15 females) underwent unsedated, transoral EndoFLIP^® measurements of the pylorus after 8 h of fasting. Measurements of diameter (DM), balloon pressure, and distensibility index (DI) of the pylorus were obtained twice over 5 min at 40, 50, and 60 ml balloon distensions. Key Results: Pyloric DM at 40, 50, and 60 ml balloon distensions were 13.0 ± 2.5, 14.3 ± 1.8, and 17.2 ± 2.0 mm, respectively. DM with 60 ml distension was notably higher than with 40 and 50 ml distensions. Pyloric DI at 40, 50, and 60 ml distensions were 10.9 ± 4.8, 11.3 ± 5.8, and 11.1 ± 4.3 mm²/mm Hg, respectively (p = 0.86). Linear regression and Bland–Altman plots showed similar distribution of the DM and DI during the second minute compared with the full 5-min measurements at 50 ml distension, as well as between two sequential measurements using 50 ml distension. With 50 ml balloon distension, intraindividual coefficients of variation (COV_intra) for DM and DI were 13.8% and 29.6%, respectively, and interindividual COV (COV_inter) were 12.6% and 51.3%, respectively. Similar reproducibility was obtained with 40 ml balloon distension. Conclusions and Inferences: Unsedated EndoFLIP^® can be used to characterize human fasting pyloric diameter and distensibility, with best performance observed with 40 ml and 50 ml distensions and data collection during the second minute. Normative values reported serve as reference values for future studies.