Addressing Gaps in the Chicago Classification Version 4.0: Defining an Optimal Intrabolus Pressure Measurement on Esophageal Manometry

BACKGROUND: Intrabolus pressure (IBP) reflects the pressure within the esophageal lumen during bolus transit and serves as a physiologic marker of outflow resistance at the esophagogastric junction (EGJ). The lack of a standardized or validated method to measure IBP is a critical limitation for interpreting high resolution manometry (HRM) and identification of clinically relevant EGJ outflow obstruction (EGJOO). METHODS: Three distinct cohorts, "Controls", Normal motility", and "conclusive EGJOO" were selected from a prospectively enrolled cohort of adult patients. All patients had at least undergone HRM with impedance (HRIM), and functional lumen impedance probe (FLIP) testing. 4D HRM analysis was performed blinded to clinical characteristics. 4D HRM IBP results were assessed on a per-swallow and also on a per-patient level. Receiver operating curve (ROCs) to assess each metrics prediction of conclusive EGJOO vs. not EGJOO (normal motility and controls) were utilized for the per-swallow analysis. KEY RESULTS: 33 controls, 35 normal motility, and 15 conclusive EGJOO patients were included. Swallow level analysis was conducted on 156 swallows, 165 swallows, and 61 swallows from each group, respectively. Per-swallow analysis demonstrated differences between conclusive EGJOO, normal motility, and controls for all ten IBP measures (P-values < 0.001), with greater IBP measures in conclusive EGJOO than in normal motility and controls. The 1 s max IBP had the greatest AUROC. CONCLUSIONS & INFERENCES: Standardized measurement of IBP using an optimized method (1-s max IBP) within the 4D-HRM framework with impedance-confirmed bolus tracking and phase-specific measures represents a physiologically grounded and clinically meaningful advance in HRIM interpretation.