Assessment of the Food-Swallowing Process Using Bolus Visualisation and Manometry Simultaneously in a Device that Models Human Swallowing.
Waqas M Qazi, Olle Ekberg, Johan Wiklund and 2 others
PMID 30840137WHAT IT FOUND
In a throat-shaped machine, thicker liquids moved more slowly, had lower wall shear rates, and produced higher pressures than thinner liquids.
This is device testing, not patient evidence, so it cannot show what happens when someone swallows.
Key findings
01Average fluid velocities ranged from 0.046 ± 0.02 m/s to 0.48 ± 0.05 m/s, increasing as bolus consistency decreased.
02In the simulator, the lowest-consistency bolus reached a shear rate of about 209 s^-1, while the pudding-thick bolus reached 13 ± 6 s^-1.
03In the model, the 2.0 Pa s bolus produced higher pressures than the 1.0 Pa s bolus at the pharynx entrance, mid-pharynx, and near the upper oesophageal sphincter.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
No patients or clinicians were studied, so the results cannot show safety, aspiration risk, or treatment benefit in real swallowing. The device simplifies swallowing: it uses a syringe pump and fixed valves, and the authors state in vitro manometry results are not directly comparable to in vivo examinations. The model did not reproduce all biological factors involved in human swallowing, such as peristalsis, laryngeal movement, and epiglottal and sphincter movements. The study tested a commercial thickener but did not compare brands, patient preferences, or clinical outcomes.
Declared interests
Funding was from Svenska Forskningsrådet Formas. The study tested a thickener from Nutricia Nordic AB. No author conflict-of-interest declarations are given in the supplied text.
The easy way to misread this
Do not read these pressure and velocity changes as evidence that thicker liquids are safer or harder for patients. They were measured in a machine, not in people, and the device does not reproduce muscle movement, airway closure, or digestion.