Functional Luminal Imaging Probe (FLIP) as an Adjunctive Modality in Evaluation of Esophageal Dysmotility

The Functional Luminal Imaging Probe (FLIP) has emerged as a valuable adjunctive tool in the evaluation of esophageal diseases. Using volumetric distension, FLIP can assess secondary peristalsis and detect esophageal abnormalities that may not be evaluated by high-resolution manometry (HRM). In certain clinical settings, FLIP may allow for deferral of HRM. In therapy for esophageal diseases, FLIP has demonstrated value for its real-time interpretation, which can be used intra-procedurally to tailor therapy and to predict post-therapy outcomes. The future of FLIP looks promising as surgeons and gastroenterologists place increasing emphasis on non-manometric data to diagnose esophageal motility disorders.

Assessment of esophageal body peristaltic work using functional lumen imaging probe panometry

Background: The goal of this study was to conceptualize and compute measures of "mechanical work" done by the esophagus using data generated during functional lumen imaging probe (FLIP) panometry and compare work done during secondary peristalsis among patients and controls. Methods: 85 individuals were evaluated with a 16 cm FLIP during sedated endoscopy, including controls (n=14), achalasia subtypes I, II and III (n=15, each), GERD (n=13), EoE (n=9) and SSc (n=5). The FLIP catheter was positioned to have its distal segment straddling the EGJ during stepwise distension. Two metrics of work were assessed: "active work" (bag volumes ≤ 40 mL where contractility generates changes in lumen area) and "work capacity" (bag volumes ≥ 60 mL when contractility cannot alter the lumen area). Results: Controls showed median (IQR) of 7.3 (3.6-9.2) mJ of active work and 268.6 (225.2-332.3) mJ of work capacity. All achalasia subtypes, GERD, and SSc showed lower active work done than controls (p≤0.003). Achalasia subtypes I, II, GERD, and SSc had lower work capacity compared to controls (p<0.001, 0.004, 0.04, and 0.001 respectively). Work capacity was similar between controls, achalasia type III and EoE. Conclusions Mechanical work of the esophagus differs between healthy controls and patient groups with achalasia, EoE, SSc and GERD. Further studies are needed to fully explore the utility of this approach, but these work metrics would be valuable for device design (artificial esophagus), to measure the efficacy of peristalsis, to gauge the physiological state of the esophagus, and comment on its pumping effectiveness.

Characterization and mechanism of the esophago-esophageal contractile reflex of the striated muscle esophagus

An esophago-esophageal contractile reflex (EECR) of the cervical esophagus has been identified in humans. The aim of this study was to characterize and determine the mechanisms of the EECR. Cats ( n = 35) were decerebrated, electrodes were placed on pharynx and cervical esophagus, and esophageal motility was recorded using manometry. All areas of esophagus were distended to locate and quantify the EECR. The effects of esophageal perfusion of NaCl or HCl, vagus nerve or pharyngoesophageal nerve (PEN) transection, or hexamethonium administration (5 mg/kg iv) were determined. We found that distension of the esophagus at all locations activated EECR rostral to stimulus only. EECR response was greatest when the esophagus 2.5–11.5 cm from cricopharyngeus (CP) was distended. HCl perfusion activated repetitively an EECR-like response of the proximal esophagus only within 2 min, and after ~20 min EECR was inhibited. Transection of PEN blocked or inhibited EECR 1–7 cm from CP, and vagotomy blocked EECR at all locations. Hexamethonium blocked EECR at 13 and 16 cm from CP but sensitized its activation at 1–7 cm from CP. EECR of the entire esophagus exists, which is directed in the orad direction only. EECR of striated muscle esophagus is mediated by vagus nerve and PEN and inhibited by mechanoreceptors of smooth muscle esophagus. EECR of smooth muscle esophagus is mediated by enteric nervous system and vagus nerve. Activation of EECR of the striated muscle esophagus is initially sensitized by HCl exposure, which may have a role in prevention of supraesophageal reflux.NEW & NOTEWORTHY An esophago-esophageal contractile reflex (EECR) exists, which is directed in the orad direction only. EECR of the proximal esophagus can appear similar to and be mistaken for secondary peristalsis. The EECR of the striated muscle is mediated by the vagus nerve and pharyngoesophageal nerve and inhibited by mechanoreceptor input from the smooth muscle esophagus. HCl perfusion initially sensitizes activation of the EECR of the striated muscle esophagus, which may participate in prevention of supraesophageal reflux.