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Introduction:
A manometrically normal lower esophageal sphincter (LES) is necessary to protect the esophagus from exposure to gastric juice. Manometric measurements related to the competency of the LES are resting pressure, overall length, and the length exposed to the environmental pressure of the abdomen. We hypothesized that the magnitude of the esophageal acid exposure is related to the degree of permanent deterioration of the LES.
Methods:
The records of 2,723 patients referred to our esophageal function laboratory for the assessment of reflux symptoms between 1998-2008 were reviewed. Those with a named motility disorder or previous foregut surgery were excluded. The study population consisted of the remaining patients, who had a detailed assessment of their LES with slow motorized pull-through manometry and an abnormal 24-hour pH monitoring study off acid suppression therapy. The LES was graded on a scale of 0-3, according to the number of abnormal LES components on manometry using previously defined normal values for resting pressure (<5.1mmHg), overall length( < 2.7cm) and abdominal length (< 1.4cm). Grade 0 indicated all components were normal; 1, only one component abnormal; 2, two components abnormal; 3, all three components abnormal.
Results:
The final study group consisted of 918 patients (58% male, median age 53 and median BMI 28.3) who met the inclusion criteria and had an abnormal 24-hour composite pH score as objective evidence for GERD. Of these 406(44%) had grade 0, 152(17%) grade 1, 272(30%) grade 2 and 88(9%) grade 3 LES. Corresponding values for the median (IQR) composite pH score were 30.9(20.6-46.5), 39.5(23.1-57.8), 42.0(27.0-75.1) and 63.2(31.8-90.2) respectively (p<0.0001, Kruskal-Wallis test). Patients with a normal LES at rest had less esophageal acid exposure compared to those with one or more LES manometric abnormalities (30.9 vs. 42.2, p<0.0001, Mann-Whitney U-test). The values for all three LES components, irrespective of the LES grade, were inversely correlated to the composite pH score: total length (r= -0.23), abdominal length (r= -0.22) and resting pressure (r= -0.28), (p<0.0001 for all 3 analyses). The most common abnormal manometric finding was a short overall length and the least common was a hypotensive LES pressure.
Conclusion:
Permanent manometric abnormalities of the LES measured at rest are associated with increased esophageal acid exposure. The degree of acid exposure is related to the extent of the manometric abnormalities. Forty four percent of the GERD patients have a normal LES measured at rest despite having increased esophageal acid exposure. These patients have the lowest esophageal acid exposure and are likely to have transient manometric abnormalities of the LES during periods of activity.