Abstract
Drinks and foods may be thickened to improve swallowing safety for dysphagia patients, but the resultant consistencies are not always palatable. Characterising alternative appetising foods is an important task. The study aims to characterise the in vitro swallowing behaviour of specifically formulated thickened dysphagia fluids containing xanthan gum and/or starch with standard jellies and yoghurt using a validated mechanical model, the “Cambridge Throat”. Observing from the side, the model throat can follow an experimental oral transit time (in vitro-OTT) and a bolus length (BL) at the juncture of the pharynx and larynx, to assess the velocity and cohesion of bolus flow. Our results showed that higher thickener concentration produced longer in vitro-OTT and shorter BL. At high concentration (spoon-thick), fluids thickened with starch-based thickener showed significantly longer in vitro-OTT than when xanthan gum-based thickener was used (84.5 s ± 34.5 s and 5.5 s ± 1.6 s, respectively, p < 0.05). In contrast, at low concentration (nectar-like), fluids containing xanthan gum-based thickener demonstrated shorter BL than those of starch-based thickener (6.4 mm ± 0.5 mm and 8.2 mm ± 0.8 mm, respectively, p < 0.05). The jellies and yoghurt had comparable in vitro-OTT and BL to thickeners at high concentrations (honey-like and spoon-thick), indicating similar swallowing characteristics. The in vitro results showed correlation with published in vivo data though the limitations of applying the in vitro swallowing test for dysphagia studies were noted. These findings contribute useful information for designing new thickening agents and selecting alternative and palatable safe-to-swallow foods.
Highlights
Dysphagia, characterised by a difficulty in swallowing, is a complication associated with several conditions, including stroke, dementia and neurological disorders [1]
In agreement with published data [7, 13], we found that increasing thickener content increased the in vitro-OTT, which corresponded to an increase in apparent viscosity in the test shear rate range
This agreed with published findings for which that xanthan gum solutions travelled at high velocity in the in vitro model similar to that of low-medium viscosity Newtonian fluids [7, 13]
Summary
Dysphagia, characterised by a difficulty in swallowing, is a complication associated with several conditions, including stroke, dementia and neurological disorders [1]. Dysphagia can lead to food avoidance, in the elderly, which may result in serious consequences such as nutritional and respiratory complications, and even death [4, 5]. Adding thickeners to drinks and food is a popular management strategy for dysphagia. Thickeners increase the viscosity of thin drinks and food stuffs making them easier and safer to swallow [6]. Increasing bolus viscosity helps the bolus to remain in the oral phase for longer [7], giving the patient more time for reflex responses and muscular adjustments essential for safe swallowing [8]
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