Normal values for oesophageal motility and function during multiple swallows of low vs high viscosity liquid

Abstract

Background and aims: High resolution manometry (HRM) with spatiotemporal presentation of pressure data provides a detailed representation of esophageal anatomy, motility and function. In the pharynx, raised Intrabolus pressure (IBP) with a steep intrabolus pressure gradient on HRM identifies clinically significant resistance to flow in the region of the upper esophageal sphincter. The same principle can be applied to identify pathology that obstructs bolus passage also in the esophagus and lower esophageal sphincter (LES); however larger volumes are required due to the greater capacity of the distal esophagus. The sensitivity of this test to detect pathology may be increased by ingestion of high viscosity fluids compared to water; however normal values for these tests have not been established. The aim of this study was to compare esophageal function with 200ml high viscosity vs. low viscosity liquid swallows in the physiologic, upright seated, position. Method: 9 healthy subjects (male:female 5:4, age 20-44) underwent HRM using a 36 channel solid state assembly (Manoscan 360, Sierra Scientific Instruments). After standard 10x5ml water swallows, 200ml of water (viscosity 1cPois) and 200ml of a thick lactose-free fruit-smoothie (100Kcal, ~100cPois) were ingested in consecutive order. Volunteers were asked to drink the liquid through a straw without stopping. Spatiotemporal plots of 5ml water and large volume multiple swallows were assessed. Results are presented as Median (Interquartile range). Chi square test was used for qualitative analysis and Wilcoxon test was used to for nonparametric quantitative group comparisons. Results: A similar number of swallows were required to drink the high and low viscosity liquid (19.9 vs. 17.9; p=0.4); however the duration required to ingest the smoothie was greater (35sec (33.49sec) vs. 25sec (22.30sec; p=0.018). Complete suppression of esophageal contractility was achieved for all water and 7/9 fruit-smoothie swallows. IBP was somewhat higher for 5ml water swallows (8.9mmHg (6.7.13.8mmHg)) compared to 200ml water (3.6mmHg (2.5.4.6)) and 200ml smoothie (3.0mmHg (0.0.4.4mmHg)), although this difference was non-significant (p=0.109 and 0.139 respectively). A powerful post-contraction was observed in most patients after drinking the smoothie and water (8 vs. 5/9 patients; p=0.294) followed by an increase in LES post-contraction pressure (12.7 vs. 7.1mmHg; p=0.144) respectively. Conclusion: This study compares the function of the healthy esophagus to free drinking of high vs low viscosity fluids. Furthermore it provides reference values for future clinical studies to assess the clinical utility of including high viscosity fluids in HRM investigation of patients with esophageal symptoms.