Esophageal pressure topography, body position, and hiatal hernia

INTRODUCTION:: Whether body position affects lower esophageal sphincter (LES) function and detection of hiatal hernia is unknown. Moreover, the yield of high-resolution esophageal pressure topography (HREPT) when compared with endoscopy for detection of hiatal hernia is unclear. AIM:: The aims of this study were to examine (a) the effects of body position (standing vs. supine) on LES function, and (b) to determine the diagnostic yield of HREPT and endoscopy for detection of hiatal hernia. METHODS:: A total of 50 subjects underwent both HREPT and endoscopy. The manometric/topographic changes of LES were examined in both supine and standing positions. Endoscopy assessed presence and length of hiatal hernia. Diagnostic agreement was compared between HREPT and endoscopy. RESULTS:: The resting LES pressure was higher (P=0.0001), its mean length was longer (P=0.0003), and length of high-pressure zone was longer (P=0.0001) in the standing position compared with the supine position. HREPT detected twice as many subjects with hiatal hernia in standing (P=0.0001) compared with supine position or endoscopy with significant new diagnostic information (79%). Endoscopy detection rate (34%) was similar to supine manometry with good diagnostic agreement (77%) between HREPT and endoscopy. Hiatal hernia length was longer (P=0.0001) with HREPT in standing position compared with endoscopy. CONCLUSIONS:: Body position significantly affects in the LES function and its measurements. HREPT when performed on standing position offers the best yield for detection of hiatal hernia and is superior to endoscopy or supine manometry.