PURPOSE: Dysphagia can lead to malnutrition and aspiration of oral feeds causing pneumonia. Dysphagia diet foods (DDF) are thickened based on the results of a swallowing evaluation as recommended by the National Dysphagia Diet (NDD) guidelines. There are no published data relating how the viscosity of barium test feeds (BTF) or DDF meets NDD guidelines or if handing DDF changes viscosity.
METHODS: A TA1000 rheometer measured dynamic viscosity using creep transformation under controlled stress at shear rates from 0.01 to 100 rad/sec. Thin DDF studied include Boost Plus and Carnation Breakfast and nectar- and honey-thick DDF from Hormel and Novartis (Resource). The BTF studied were thin EZ-HD, Varibar nectar- and honey-thick (EZ-EM Inc), and Polibar Plus (nectar). We measured batch-to-batch variability in the viscosity of DDF with and without shaking and after 2 hours at ambient temperature.
RESULTS:  DDF: The viscosity of Resource and Hormel Honey thick were consistent with NDD guidelines while Hormel nectar was honey-thick at opening. Resource Honey and Nectar showed minimal variability in viscosity while Hormel Honey was variable between lots. All products had minimal change in viscosity over 2 hours. Resource and Boost had >200% increase in viscosity after shaking.  BTF: Thin barium had a viscosity consistent with NDD guidelines. The nectar- and honey-thick Polibar contrast BTFs were thixotropic and at low stress had unacceptably high viscosity. Varibar BTFs were not thixotropic but all were more viscous than corresponding DDF or the NDD guidelines. EZ-EM has developed unique definitions of thin, nectar, and honey-thick that differ from the NDD guidelines.
CONCLUSION: There was a poor relationship between the viscosity of DDF and BTF with the latter falling well outside NDD target viscosity guidelines. Furthermore, the viscosity of DDF can change with handling.
CLINICAL IMPLICATIONS: The viscosity of the BFTs are much greater than the correspondingly named diet foods and the NDD guidelines. This can place patents at significant risk for uncontrolled aspiration.
DISCLOSURE: Lindsay Chaney, No Financial Disclosure Information; No Product/Research Disclosure Information