Transdiaphragmatic Pressure Gradient (TPG) Has a Central Role in the Pathophysiology of Gastroesophageal Reflux Disease (GERD) in the Obese and it Correlates with Abdominal Circumference but Not with Body Mass Index (BMI)

Introduction Pathophysiology of gastroesophageal reflux disease (GERD) is multifactorial. An increased transdiaphragmatic pressure gradient (TPG) may be a main element for GERD in the obese patient. This study aims to evaluate the role of TPG in the physiopathology of GERD in obese individuals. Methods We studied 47 unselected consecutive candidates for bariatric operations (body mass index (BMI) > 35). All patients underwent high-resolution manometry and esophageal pH monitoring. Individuals were grouped as GERD + or GERD - based on DeMeester score. Abdominal pressure (AP) and thoracic pressure (TP), transdiaphragmatic pressure gradient (AP-TP), and lower esophageal sphincter (LES) retention pressure (LES basal pressure-TPG) were determined. Manometric variables were compared with a group of 20 lean healthy individuals (BMI < 25). Results There were 27 (57%) GERD + patients and 20 (43%) GERD - patients. TPG, waist circumference, LES retention pressure, and AP were higher in GERD + group as compared with GERD - individuals. GERD - group had manometric parameters similar to controls except for AP. GERD + patients had higher AP and TPG and lower LES retention pressure compared with controls. TPG and LES retention pressure correlated with waist circumference and DeMeester score. BMI correlated with AP but not with waist circumference or DeMeester score. Conclusion In the obese, GERD presence and severity were associated to a high TPG due to increase AP that correlates with waist circumference.