Endoscopic luminal impedance planimetry of the lower oesophageal sphincter and pylorus in experimental pigs: a pilot study.

Abstract

Background/aims: The functional lumen imaging probe (FLIP) relies on the principle of impedance planimetry that enables direct measurement of intraluminal pressure, cross-sectional areas, and wall biomechanical properties. The aim of our pilot project was to introduce this method to assess function of the lower oesophageal sphincter and pyloric muscle in experimental pigs.

Methods: All measurements were accomplished in one session in six adult female pigs (mean weight 34.2 ± 3.6 kg), using the EndoFLIP 1.0 System with EndoFLIP catheters. Five major parameters were evaluated: balloon pressure (mm Hg), estimated diameter (mm), cross-sectional area (mm2), distensibility (mm2/mm Hg), and zone compliance (mm3/mm Hg).

Results: In total, 180 readings were successfully accomplished. Most of the measured values were nearing lower average figures for the lower oesophageal sphincter, and upper average figures for the pylorus in healthy humans. The porcine pyloric sphincter is composed of the Torus pyloricus. It serves as a study "gatekeeper" between the stomach and D1 duodenum, thus explaining higher pyloric readings. There was a clear trend for increasing values of CSA (cross-sectional area), diameter, and balloon pressure with increased filling balloon volumes. However, the sphincter distensibility did not change with increasing filling volumes, either for the lower oesophageal sphincter or pylorus.

Conclusion: Endoscopic functional luminal planimetry in experimental pigs is feasible, both for the lower oesophageal sphincter and the pylorus. This is an important starting point for future experimental endoscopic trials and pharmacology studies.