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Gastric and lower esophageal sphincter pressures during nausea: A study using visual motion-induced nausea and high-resolution manometry

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AJP Gastrointestinal and Liver Physiology

Published online on

Abstract

Nausea is the subjective unpleasant sensation that immediately precedes vomiting. Studies using barostats suggest that gastric fundus and lower esophageal sphincter (LES) relaxation precede vomiting. Unlike barostat, high-resolution manometry (HRM) allows less invasive, detailed measurements of fundus pressure (FP) and axial movement of the gastro-esophageal junction (GEJ). Nausea was induced in 12 healthy volunteers by a motion video and rated on a visual analogue scale. FP was measured as the mean value of the five pressure channels that were clearly positioned below the LES. After intubation, a baseline (BL) recording of 15 min was obtained. This was followed by presentation of the motion video (at least 10 min, max. 20 min) followed by 30min recovery recording. Throughout the experiment we recorded autonomic nervous system (ANS) parameters (blood pressure, heart rate (HR) and cardiac vagal tone (CVT) which reflects efferent vagal activity). 10/12 subjects showed a drop in FP during peak nausea compared to BL (-4.0±0.8mmHg; p=0.005) and8/10 subjects showed a drop in LES pressure (-8.8±2.5mmHg; p=0.04). Peak nausea preceded peak fundus and LES pressure drop.Nausea was associated with configuration changes at the GEJ such as LES shortening and esophageal lengthening. During nausea we observed a significantly increased HR and decreased CVT. In conclusion, nausea is associated with a drop in fundus and LES pressure, configuration changes at the GEJ as well as changes in the ANS activity such as an increased sympathetic tone (increased HR) and decreased parasympathetic tone (decreased CVT).