THE TRANSDIAPHRAGMATIC PRESSURE GRADIENT AND THE LOWER ESOPHAGEAL SPHINCTER IN THE PATHOPHYSIOLOGY OF GASTROESOPHAGEAL REFLUX DISEASE. AN ANALYSIS OF 500 ESOPHAGEAL FUNCTION TESTS.
Natalya C. Dias, Fernando A. Herbella*, Leonardo M. Del Grande, Marco G. Patti
Department of Surgery, Universidade Federal de Sao Paulo Escola Paulista de Medicina, Sao Paulo - SP, Sao Paulo, Brazil
Background: Gastroesophageal reflux disease (GERD) pathophysiology is multifactorial, but more importance has been attributed to a defective lower esophageal sphincter (LES) than to an altered transdiaphragmatic pressure gradient (TPG). Some studies focused on the role of TPG in specific populations such as morbid obesity and chronic obstructive pulmonary disease but not in a general population.
Aims: This study aims to evaluate the role of the TPG and LES in the pathophysiology of gastroesophageal reflux disease in a general population.
Methods: 500 consecutive and unselected esophageal function tests from patients with clinically suspected GERD that underwent esophageal manometry and pHmonitoring were reviewed. Patients were grouped according to the pHmonitoring in GERD + or GERD based on the DeMeester score. Abdominal pressure, thoracic pressure, TPG (abdominal – thoracic pressures), LES basal pressure (midrespiratory, expiratory and EGJ-CI) and LES retention pressure (LES basal pressure - TPG) were determined.
Results: GERD was present in 296 (59%) individuals. GERD + patients had a higher proportion of males (table 1). LES basal pressure (by all parameters) and thoracic pressure were not different between groups. Abdominal pressure and TPG were higher in GERD + patients. LES retention pressure (by all parameters) was lower in GERD + patients. DeMeester score correlated with LES basal pressure, TPG and LES retention pressure (by all parameters) but not with abdominal pressure and thoracic pressure (figure 1).
Conclusions: LES valvar competency as measured by absolute basal pressure does not predicted GERD but was linked to GERD severity. Relative LES pressure (LES retention pressure) predicted GERD presence and severity, but no parameter had proved superiority. TPG plays an important role in the pathophysiology of gastroesophageal reflux disease since it is linked to GERD presence and severity but TPG is altered in a general population mostly based on a higher abdominal pressure.
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