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

Abstract

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.

A mechanics--based perspective on the function of human sphincters during functional luminal imaging probe manometry

“…The study protocol was approved by the Northwestern University Institutional Review Board. This control cohort overlaps previous publications [44,45,46,47,48,49,50].…”

Pressure -- area loop based phenotypic classification and mechanics of esophagogastric junction physiology

“…We examined 192 contractile cycles of 24 randomly selected, asymptomatic volunteers, and plotted their pressurearea loops, identifying the opening and closing curves. The FLIP data used in this study was collected at the Esophageal Center of Northwestern between November 2012 and October 2018, using a 16-cm FLIP (EndoFLIP ® EF-322N; Medtronic, Inc, Shoreview, MN) [14,15]. Additional details on the data collection process and subject cohort selection is available in [14,16,10,15].…”

“…The FLIP data used in this study was collected at the Esophageal Center of Northwestern between November 2012 and October 2018, using a 16-cm FLIP (EndoFLIP ® EF-322N; Medtronic, Inc, Shoreview, MN) [14,15]. Additional details on the data collection process and subject cohort selection is available in [14,16,10,15]. We characterize a contractile cycle by at least 3 cm decrease in the luminal diameter and contractions of at least 6cm traveling forward along the length of the esophagus [14,15].…”

“…Additional details on the data collection process and subject cohort selection is available in [14,16,10,15]. We characterize a contractile cycle by at least 3 cm decrease in the luminal diameter and contractions of at least 6cm traveling forward along the length of the esophagus [14,15]. By making the distinction between the opening and closing curves, we identified two, equally appearing, physically meaningful loop types.…”

“…This is because contraction speed does not widely vary across subjects. By looking at clinical FLIP recordings of different contractile cycles, the active contraction of the EGJ is set by the peristaltic wave, similar to the pattern used in the model above [14,16,10]. Therefore, the EGJ contraction speed depends on the speed of the traveling wave.…”