473 Pathophysiology of Gastroesophageal Reflux in Patients With Chronic Pulmonary Obstructive Disease Is Linked to an Increased Transdiaphragmatic Pressure Gradient Not a Defective Esophagogastric Barrier

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The association of gastroesophageal reflux disease (GERD) and pulmonary diseases is well known. Early studies showed that gastroduodenal contents may reflux up to the proximal esophagus and cause aspiration. Other studies showed a higher incidence of GERD in patients with asthma, interstitial fibrosis, chronic cough, and chronic obstructive pulmonary disease (COPD). Esophageal (or typical) GERD symptoms (heartburn, regurgitation, and dysphagia) are not always present in these patients, and even when they are reported, they yield a low accuracy for GERD diagnosis. Extra-esophageal symptoms such as cough are common and thus represent a confounding factor. As a consequence, clinical questionnaires are insufficient and objective determination of GERD is mandatory for the correct management of these patients. COPD is attributed to tobacco smoking in the majority of cases, different from adult asthma and pulmonary fibrosis that, although still considered idiopathic, have GERD as a putative etiologic factor. However, a great number of smokers will never develop COPD leading to the suggestion that tobacco alone is not responsible for the disease in every patient and that aspiration of gastroduodenal contents may play a contributory role. In addition, COPD disrupts the ventilatory dynamics, and this may promote abnormal reflux. COPD is probably the main pulmonary disease that lacks a satisfactory number of studies dealing with objective evaluation of esophageal motility and acid exposure by esophageal function tests.We believe that the study of the incidence of GERD, esophageal motility, and ventilatory dynamics by esophageal manometry and ambulatory pHmonitoringmay shed some light on the association between COPD and GERD. This study aims to evaluate in patients with COPD (1) the incidence and profile of GERD, (2) esophageal motility, and (3) the transdiaphragmatic pressure gradient.