Role of the lower esophageal sphincter on acid exposure revisited with high-resolution manometry

The objective of this study was to investigate the role of lower esophageal sphincter (LES) length and pressure on acid exposure with high-resolution manometry (HRM).

After Institutional Review Board approval, a retrospective review of a prospectively maintained database identified patients who had undergone HRM and 24-hour pH studies. Abdominal LES length (AL) ≤1 cm and overall LES length ≤2 cm were considered inadequate. A new parameter called lower esophageal sphincter pressure integral (LESPI) was analyzed in this study. Distal esophageal acid exposure was analyzed in relation to LES parameters.

One hundred eight patients (inadequate AL, n = 54; inadequate overall LES length, n = 54) satisfied study criteria. Patients with inadequate AL had considerably lower LESPI and LES pressure. They also had more severe acid exposure and higher DeMeester score. However, inadequate overall LES length was not associated with abnormal acid exposure. Patients with a positive pH study had considerably lower LESPI than patients with a negative pH study. Inadequate AL and low LESPI (<400 mmHg/s/cm) had a synergistic effect on acid reflux. Multivariate logistic regression analysis identified inadequate AL, low LESPI, and male sex as predictors of a positive pH study.

Using HRM, inadequate AL (≤1cm) and low LESPI (<400 mmHg/s/cm) are associated with gastroesophageal reflux disease and appear to have a synergistic effect on the severity of distal esophageal acid exposure. LESPI, which is a function of both sphincter length and pressure, appears to be the most sensitive HRM parameter for distal esophageal acid exposure.