Accuracy of speech-language pathologists replicating barium sulfate viscosity
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Abstract
Changes in bolus viscosity effect changes in oropharyngeal swallowing physiology, in some cases resulting in a more efficient swallow for dysphagic patients. Thus, systematic variation of bolus viscosity is often implemented as a diagnostic tool during the modified barium swallow evaluation. However, there is no universal standard for the definition and variation of bolus viscosity during the procedure. Clinicians rely upon subjective judgements (e.g., stirring, pouring, or "eyeing" solutions) to determine appropriate protocols.
The goal for this study was to examine the relationship between subjective and objective measurements of viscosity. Two research questions were raised: Can experienced clinicians (1) accurately and (2) reliably replicate barium sulfate viscosity using only subjective judgements? Ten speech-language pathologists, experienced in performing modified barium swallow studies, attempted to replicate three barium sulfate solutions of predetermined viscosity using liquid barium sulfate (HD85'™) and water. Clinicians performed the task three times for each solution. Flow curves were obtained using a dynamic, rotational viscometer (the Rheomat RM 180™0. Viscosity (Pa s) of each sample was determined as a function of a wide range of shear rates (s").
Multiple conelation statistics indicated clinicians were neither accurate nor reliable in their attempts to match solution viscosity using only subjective judgements. These results suggest a need for reevaluation of ciurent diagnostic procedures employed in dysphagia management. The potential usefulness of rheologically defined barium sulfate protocol and the need for additional research in this area are discussed.