Are We Testing a True Thin Liquid?

Abstract

The purpose of this study was to examine the effects on a patient's swallowing of diluting E-Z-EM's Varibar((R)) Thin liquid barium product (which is often used in videofluoroscopic swallow studies) to achieve a consistency closer to water. Forty patients who were 18 years and older participated in this study. Their varied medical diagnoses included stroke, pneumonia, TBI, and cancer as well as diagnoses not usually associated with dysphagia such as abdominal pain and rhabdomyolysis. To screen for aspiration, E-Z-EM's Varibar Thin liquid was presented to patients to swallow as 2 cc, 5 cc, cup, and straw drinking trials. If no aspiration occurred, the patient was given the Varibar Thin liquid diluted by 50% using water (referred to as Ultrathin) to swallow in the same amounts. Then occurrence of aspiration with the Ultrathin liquid was compared to the occurrence of aspiration when the patient swallowed the Varibar Thin liquid. Fifty percent of patients aspirated on the Ultrathin liquid but not on the Varibar Thin liquid, across at least one of the test conditions. From these results we suggest that although E-Z-EM Varibar Thin liquid may have a low-viscosity range, it still may not be "thin enough" to identify all patients who aspirate or who are at risk for aspiration on thin liquids.

The Effect of Bolus Consistency on Hyoid Velocity in Healthy Swallowing

“…The thin liquid barium was prepared in a 40% w/v concentration by diluting Liquid Polibar® (Bracco Diagnostics Inc., Monroe Township, New Jersey) with water, to an apparent viscosity of 30 mPa.s. The “ultrathin” liquid barium [24] was prepared by diluting Liquid Polibar® with water to a 22% w/v barium concentration, with an apparent viscosity of 11 mPa.s. The ultrathin liquid was included based on a study [24] that suggests that this concentration of barium represents a true thin liquid more closely than 40% w/v barium.…”

“…The “ultrathin” liquid barium [24] was prepared by diluting Liquid Polibar® with water to a 22% w/v barium concentration, with an apparent viscosity of 11 mPa.s. The ultrathin liquid was included based on a study [24] that suggests that this concentration of barium represents a true thin liquid more closely than 40% w/v barium. For reference, water, as a true thin liquid would have constant Newtonian viscosity rather than the shear-thinning properties seen for the three barium stimuli and would appear as a horizontal straight line at a coordinate of 1mPa.s across the x-axis of Figure 1.…”

Liquid Barium is not Representative of Infant Formula: Characterisation of Rheological and Material Properties

“…This potential increase in sensory input may allow infants to swallow without incident during a VFSS and yet clinically demonstrate signs of aspiration (i.e., a false negative during radiology). In a study relating to VFSS with adults, Fink and Ross [13] confirmed that 50% of patients who were deemed safe to swallow ''Varibar thin liquid'' aspirated when the Varibar thin liquid was diluted by 50% using water. Although the viscosities of the products were not reported, the authors demonstrated that the addition of water resulted in a change of density from 1.34 to 1.19 g cm -3 .…”

Fluoroscopic Evaluation of Oropharyngeal Dysphagia: Anatomic, Technical, and Common Etiologic Factors

“…Utilizing an appropriate concentration (or density) of barium is important for proper visualization during fluoroscopic monitoring of the study. Typical concentrations for oropharyngeal swallowing examination are 40% w/v or 20% w/v [30]. These concentrations are intended to provide adequate visibility or contrast, while limiting coating of the oropharyngeal mucosa, which could be mistaken for pathophysiological post-swallow residue [31].…”