Assessment of Pyloric Sphincter Physiology Using Functional Luminal Imaging Probe in Healthy Volunteers

The functional luminal imaging probe (FLIP) can measure tissue distensibility and geometric changes through volumetric distention. The esophagogastric junction has been well studied using EndoFLIP, studies on pylorus are lacking. We aim to study biomechanical properties of pylorus using EndoFLIP to create normative data.

We performed a prospective study of 20 healthy volunteers (ages, 18-54 years; 10 men) who underwent pylorus evaluation using 12- cm FLIP placed across the pyloric sphincter. FLIP data were analyzed using FLIP planimetry plots at baseline and after administration of hyoscine butyl bromide injection.

The median pylorus distensibility index (P-DI) was 8.37 mm²/mmHg (interquartile range, 4.22-13.04 mm²/mmHg) at 40 mL balloon volume. The 90th percentile at 40 mL balloon for P-DI was 14.89 mm²/mmHg, for cross-sectional area was 244.20 mm²/mmHg, and diameter and pressure were 17.58 mm and 48.84 mmHg, respectively. There was significant increase in P-DI after administration of hyoscine butyl bromide injection (P < 0.05).

The normative values can be used as reference values for pyloric distensibility. This reference can be used in studies of related to pyloric diseases such as gastroparesis.