Fluids used during videofluoroscopy are more viscous and dense than their meal-time counterparts: Implications for dysphagic assessment

Abstract

The focus of this single center study was the objective analysis of perceived rheological differences between videofluoroscopy and mealtime fluids. Analysis of the rheological and material property characteristics of five fluids routinely used during (a) videofluoroscopy, (b) barium swallow, and (c) bedside assessments of swallowing ensued. Measurements obtained from a cone and plate geometry rheometer provided analysis of the characteristics of each fluids. These characteristics were described in terms of viscosity, density, and yield stress. Previous studies have focused only on part of the fluid make-up, that of viscosity. Results indicated marked differences in the characteristics of fluids used during videofluoroscopy compared to those taken at mealtimes. Differences were noted in all parts (viscosity, density, and yield stress) of the fluid make-up, with videofluoroscopy fluids showing higher values for all parameters. By virtue of the laws of physics, it is suggested that videofluoroscopy fluids may be more difficult to swallow than standard mealtime fluids. The merits of drawing conclusions of swallowing safety purely from videofluoroscopy results and correlating these with mealtime situations are discussed. The need for objective analysis of the rheological characteristics of fluids used during dysphagia assessments is highlighted. In light of the findings of this investigation, further multi-center studies are warranted.