Understanding the Rheological Parameters of Thickened Fluids for Dysphagia Sufferers

Abstract

An abnormality of swallowing food or fluid, known as dysphagia is a major issue throughout the world. Thickened fluids are commonly used in the medical management of individuals who suffer dysphagia, allowing for better oral and pharyngeal coordination and increasing the cohesiveness of the fluid. This reduces the risk of aspiration associated with bolus fracture while swallowing. Thickened fluids have been used for many years in healthcare centres and at home to provide nutrition and hydration to individuals with dysphagia. However, it is not always easy to obtain the correct consistency of thickened fluids. Fluids that are too thin may result in pneumonia, while over-thickened fluids may result in aspiration due to residue possibly inhaled from pharyngeal stasis. Variabilities in the consistency of thick fluids can be due to type of thickeners, solid content, serving temperature and differences in dispersing media.In Australia the consistency of thickened fluids is routinely assessed by evaluating their flow characteristics through a fork. This method is subjective. Although, several more reliable measuring devices are available to measure the thickness of the fluid, these devices are not suitable for the application of dysphagia management. For example, a rheometer can be used to accurately measure the viscosity of the fluid, but this device is not affordable for the healthcare industry. In contrast, the Line Spread Test is an affordable device to measure the thickness of the fluid, but the current investigation found it was potentially unreliable as many factors may influence the results of the measurement.A study of the rheological and material property characteristics of thickened fluids is needed to understand the behaviour of these fluids to allow patients to receive a consistent level of thickened fluids. The development of objective measurement guidelines for the three levels of thickened fluids for the Australian National Standards and a suitable measuring technique is also needed. This project therefore had three main objectives: (a) to rheologically characterise the behaviour of thickened fluids, considering a wide range of thickeners, fluids and serving conditions, (b) to determine which rheological parameter(s) are important for the application of dysphagia management, and (c) to obtain design guidelines for a reliable, inexpensive measuring device to accurately measure the relevant rheological parameter(s) of thickened fluids for the application of dysphagia management.The rheological properties of thickened fluids were examined in shear deformation to observe the effect of temperature, pH, fluid components (e.g. protein, fat and minerals) and type of thickener on the rheological parameters of thickened fluids. The rheological properties of thickened fluids across four available commercial thickener products and a range of types of fluids were iii | P a g e characterised and compared. Studies confirmed significant variabilities in rheological parameters between thickener products and disp...

In vitro and sensory tests to design easy-to-swallow multi-particulate formulations

“…On the other hand, higher slickness scores (i.e. perceived slimy sensation) were also reported for XG hydrogels compared to other cellulose or starch-based thickeners (Matta et al, 2006;Hadde, 2017). These results are consistent with the pronounced shear thinning behaviour of XG (Fig.…”

Proposal for a Standard Protocol to Assess the Rheological Behavior of Thickening Products for Oropharyngeal Dysphagia

“…To measure the shear viscosity, the TP is submitted to different shear flows, and the apparent viscosity at each point is recorded in order to determine the viscosity values when the bolus is submitted to the shear forces when swallowing. TPs have non-Newtonian pseudoplastic behavior, which means that shear viscosity (ShV) decreases with the increment of shear forces [ 2 , 13 , 14 ] and needs to be tested at several shear rates to understand its behavior [ 15 ]. The shear rate spectrum for the whole swallowing process in humans is estimated to range between 1 to 1000 s −1 [ 15 ], and two major landmarks have been proposed to replicate the swallowing process in patients with OD.…”