Defining lower esophageal sphincter physiomechanical states among esophageal motility disorders using functional lumen imaging probe panometry

Background: Functional lumen imaging probe (FLIP) panometry assesses esophageal motility in response to controlled volumetric distension. This study aimed to describe the physiomechanical states of the lower esophageal sphincter (LES) in response to serial filling/emptying regimes for esophageal motility disorders. Methods: Fourty-five patients with absent contractile response on FLIP and diagnoses of normal motility (n = 6), ineffective esophageal motility (IEM; n = 8), scleroderma (SSc; n = 10), or nonspastic achalasia (n = 21) were included, as were 20 patient controls with normal motility on FLIP and manometry. LES diameter and pressure were measured after stepwise FLIP filling at 60 mL, 70 mL, and emptying to 60 mL with relative changes used to define physiomechanical states. Key Results: Passive dilatation after FLIP filling occurred in 63/65 (97%) patients among all diagnoses. After FLIP emptying, passive shortening occurred in 12/14 (86%) normal motility/IEM, 10/10 (100%) SSc, 9/21(43%) achalasia, and 16/20 (80%) controls, with auxotonic relaxation seen in 2/14 (14%) normal motility/IEM, 12/21 (57%) achalasia, and 4/20 (20%) controls. After achalasia treatment (LES myotomy), 21/21 (100%) achalasia had passive shortening after FLIP emptying. Conclusions & Inferences: Physiomechanical states of the LES can be determined via response to FLIP filling and emptying regimes. While passive shortening was the general response to FLIP emptying, auxotonic relaxation was observed in achalasia, which was disrupted by LES myotomy. Further investigation is warranted into the clinical impact on diagnosis and treatment of esophageal motility disorders.