Assessment of the Food-Swallowing Process Using Bolus Visualisation and Manometry Simultaneously in a Device that Models Human Swallowing

Abstract

The characteristics of the flows of boluses with different consistencies, i.e. different rheological properties, through the pharynx have not been fully elucidated. The results obtained using a novel in vitro device, the Gothenburg Throat, which allows simultaneous bolus flow visualisation and manometry assessments in the pharynx geometry, are presented, to explain the dependence of bolus flow on bolus consistency. Four different bolus consistencies of a commercial food thickener, 0.5, 1, 1.5 and 2 Pa s (at a shear rate of 50 s−1)—corresponding to a range from low honey-thick to pudding-thick consistencies on the National Dysphagia Diet (NDD) scale—were examined in the in vitro pharynx. The bolus velocities recorded in the simulator pharynx were in the range of 0.046–0.48 m/s, which is within the range reported in clinical studies. The corresponding wall shear rates associated with these velocities ranged from 13 s−1 (pudding consistency) to 209 s−1 (honey-thick consistency). The results of the in vitro manometry tests using different consistencies and bolus volumes were rather similar to those obtained in clinical studies. The in vitro device used in this study appears to be a valuable tool for pre-clinical analyses of thickened fluids. Furthermore, the results show that it is desirable to consider a broad range of shear rates when assessing the suitability of a certain consistency for swallowing.

Modulation of pharyngeal swallowing by bolus volume and viscosity

“…We have included these data for completeness and translatability. Future HRPM with impedance studies could explore differences between gum and starch based thickening agents, and precise bolus rheological characteristics such as elasticity, adhesiveness, cohesiveness (2) and shear thinning qualities (44,48), which may influence swallow biomechanics.…”

Texture-Modified Food for Dysphagic Patients: A Comprehensive Review

“…To minimize the risk of aspiration and dehydration, ready-to-serve commercially packaged pre-thickened (CPPT) and instant food thickeners (IFT) are used to modify beverage consistency in dysphagia management [ 20 ]. The test of masticating and swallowing solids (TOMASS), an international study that performs quantitative solid bolus ingestion assessments [ 153 ], and in vitro testing, such as that performed by Mathieu and co-workers [ 154 ] or by Qazi et al [ 155 ], are relevant tools that contribute to assess that these food types do not require further preparation by patients’ families and/or caregivers.…”

Rheological, tribological and sensory attributes of texture‐modified foods for dysphagia patients and the elderly: A review

“…Patients with dysphagia are susceptible low‐viscosity fluids given that a bolus of too‐high viscosity does demand exertion of extra force by the tongue and pharyngeal muscles to push the bolus through the oropharynx (Qazi et al , ). There is generally a lack of clear convention regarding the shear rates at which viscosities are measured despite the shear rate being used to describe the deformation rate of non‐Newtonian stimuli as the fluid layers slide over each other once the bolus is placed under stress or force.…”