Toward an Improved Understanding of Isolated Upright Reflux: Positional Effects on the Lower Esophageal Sphincter in Patients with Symptoms of Gastroesophageal Reflux

BACKGROUND: The purpose of this study was to assess the effect of body position on lower esophageal sphincter (LES) structure and function. METHODS: Symptomatic patients underwent high-resolution manometry in the supine and upright positions followed by pH testing. Regardless of whether there was a positive DeMeester score, isolated upright reflux patterns were considered present when the supine fraction of time pH <4 = 0%. Predominant-upright and predominant-supine bipositional reflux (SBR) patterns were considered present when the supine fraction of time was upright fraction of time pH <4, respectively. RESULTS: Of 128 patients, 35 isolated upright, 55 predominant-upright bipositional, and 27 SBR patients were identified. When supine, LES pressure/length was higher in upright compared to bipositional reflux patients. When upright, there was no difference in LES pressure/length between groups. The LES in isolated upright reflux patients became defective when moved from supine to upright position compared to bipositional patients, where the LES was defective regardless of position. Although the incidence of laryngopharyngeal reflux (LPR) events was comparable between groups, isolated upright patients commonly had a normal DeMeester score. CONCLUSION: Position impacts LES competency in those with upright reflux and would not be detected with supine manometry. Upright reflux can be associated with GERD and LPR despite negative pH testing.