Physiological response of lower esophageal sphincter pressure to abdominal pressure in obese individuals: a retrospective cross-sectional study.

BACKGROUND: The physiological response of the lower esophageal sphincter (LES) to abdominal pressure (AP) plays a key role in the esophagogastric junction (EGJ) integrity. However, in obesity, this interplay remains unclear, particularly in the presence of anatomical alterations. AIMS: This study aims to evaluate the correlation between abdominal pressure and LES basal pressure in obese patients, and to analyze the influence of EGJ morphology on this interaction. METHODS: This retrospective cross-sectional study included 47 obese patients (BMI>35 kg/m2) who underwent high-resolution esophageal manometry. Patients were divided into two groups based on EGJ morphology: normal (Type I) and abnormal (Types II/III, hiatal hernia) and were compared based on clinical and manometric variables. Correlation analyses between AP and LES pressure were performed for the entire sample and stratified by EGJ morphology. RESULTS: No statistically significant correlation was found between AP and LES pressure in the overall sample (rho=0.05; p=0.737). In the subgroup analysis, there was a non-significant trend toward increased LES pressure in patients with normal EGJ morphology (r=0.26; p=0.150) and decreased LES pressure in those with hiatal hernia (r=-0.39; p=0.131). No significant differences in BMI, abdominal circumference, AP, or LES pressure were observed between groups. CONCLUSIONS: In obese individuals, abdominal pressure does not show correlation with LES pressure. However, EGJ morphology may influence sphincteric behavior, with a trend toward LES pressure increase in normal EGJ and reduction in altered morphologies. These findings highlight the multifactorial nature of esophagogastric dysfunction.