科研之友
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摘要
A method for determining the characteristic shear rates of fluids in the pharynx is advanced here using videofluorography on three healthy subjects. Bolus velocity (V) was measured for five Newtonian fluids (using different concentrations of glucose syrup), with viscosities in the range of 0.0089-0.657Pa%26lt;bold%26gt;s%26lt;/bold%26gt;, and was expressed as a function of viscosity (). Shear thinning liquid food (with four different thickener concentrations) was also used where the apparent viscosities were adjusted to match the Newtonian fluid viscosities in the shear rate range of 10-1,000/s. The Newtonian and shear thinning liquid bolus velocities were both assumed to follow the same function V=F(), which gave the shear thinning liquid characteristic viscosities (c) [=F-1(V)]. Substituting (c) into the rheological model gave values of 120 and 990/s were found at the meso- and hypopharynx, respectively, and these were approximately independent of (c) (and thickener concentration). V was found to be a function of both the characteristic viscosity and the differences between the individuals tested. %26lt;br%26gt;Practical ApplicationsThe viscosity of liquid foods (e.g., in care homes) can be increased using a thickener, suppressing the effects of swallowing disorders. Thickened liquid food shows viscous shear thinning behavior, and the apparent viscosity depends on shear rate. When the viscosity of the food is adjusted for a patient with a swallowing disorder, the viscosity should be measured at the shear rate that dominates the liquid bolus flow at the pharynx. The measured viscosity is expected to correlate well with the bolus flow characteristics. The new experimental methodology proposed herein can be used to determine the characteristic shear rate at the pharynx.
- 出版日期2014-12
