AIM: High-resolution manometry (HRM) provides a spatially enhanced, dynamic representation of the esophagogastric junction (EGJ) high-pressure zone making it possible to isolate the crural diaphragm (CD) contraction from expiratory lower esophageal sphincter (LES) pressure. This study compared CD function of subjects with and without gastroesophageal reflux disease (GERD). METHODS: A total of 75 asymptomatic controls and 156 GERD patients (EGD or pH monitoring positive) underwent HRM. The EGJ axial pressure profile was analyzed over five respiratory cycles to quantify the position and contractile vigor of the CD relative to the LES. Correlations between EGJ HRM attributes and GERD status were examined. RESULTS: GERD patients had significantly greater CD-LES separation compared with either controls or EGD-/pH- patients. GERD patients also had significantly less inspiratory augmentation of EGJ pressure (EGD-/pH+, 11.5 ± 1.9 mmHg; EGD+, 10.0 ± 1.2 mmHg) compared with controls (16.9 ± 1 mmHg) or EGD-/pH- patients (16.7 ± 0.2 mmHg). Using a logistic regression model that simultaneously examined expiratory LES pressure, LES-CD separation, and inspiratory EGJ augmentation while controlling for age and BMI, only inspiratory augmentation had a significant independent association with GERD. CONCLUSIONS: HRM characterization of EGJ morphology correlates with the objective demonstration of GERD. Although both LES pressure and LES-CD separation are associated with GERD, the strongest association and the only independent predictor of GERD as a categorical outcome in a logistic regression analysis was impaired CD function as indicated by reduced inspiratory augmentation of EGJ pressure.
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