Co-author: Debra M. Suiter, PhD, CCC-SLP, BCS-S


Difficulty swallowing (dysphagia) can occur during any point across the lifespan and it is a symptom of a more serious medical condition.  Dysphagia is a skill-based disorder that results in disruption in the safety, efficiency, and/or adequacy of nutritional intake (Dodrill & Gosa, 2015).  It can result in compromise to the integrity of the respiratory system through nasopharyngeal backflow, laryngeal penetration, and aspiration (Tutor & Gosa, 2012; Schechter, 1998).  Additionally, it can directly impact nutritional intake causing unintended weight loss in adult populations and growth faltering in pediatric populations (Salassa, 1999; Dodrill & Gosa, 2015).  Therefore, accurate identification and effective management of dysphagia is imperative to the health and well-being of individual’s with dysphagia regardless of their age (Cook, 2008; Newman, 2000).  Accurate identification of physiologic swallowing impairment and its resulting complications requires instrumental assessment such as the videofluoroscopic swallow study (VFSS) (O’Donoghue & Bagnall, 1999).  

The VFSS can distinguish the anatomic and/or physiologic causes of an individual’s oropharyngeal swallowing impairment across the age continuum (O’Donoghue & Bagnall, 1999). Additionally, it can determine the effectiveness of selected compensatory strategies to reduce or eliminate airway compromise due to impaired swallowing.  Most importantly, information gained through analysis and interpretation of the VFSS guides the speech-language pathologist in discerning the breakdown in swallowing function that must be targeted in order to bring about recovery from dysphagia for patients across the lifespan (Martin-Harris, Logemann, McMahon, Schleicher, & Sandidge, 2000).  The information gained through VFSS is heavily dependent upon the protocol utilized by the SLP in the administration of this instrumental exam.  

Applying a standardized VFSS protocol allows for collection of baseline swallowing function for each individual tested and allows for accurate comparison of a patient’s swallowing function between repeated VFSS (Martin-Harris, Canon, Bonilha, Murray, Davidson, & Lefton-Greif, 2020). Various VFSS protocols are suggested in the literature and provide guidance regarding factors such as consistencies to be administered, recommended number of trials, and order of texture administration (Newman, 2000; Hutcheson, Barrow, Barringer, Knott, Lin, Weber… & Lazarus, 2017; Martin-Harris, Humphries, & Garand, 2017; Martin-Harris, Carson, Pinto, & Lefton-Greif, 2020; McGrattan, McGhee, McKelvey, Clemmens, Hill, DeToma… & Martin-Harris, 2020).  Despite empirical evidence to support the use of standardized VFSS protocols, they are not widely applied in clinical practice for a variety of reasons.  SLPs that are not routinely administering VFSS to any published protocol are encouraged to consider the following important variables for providing VFSS at their facility: 1) selection of barium materials, 2) determining liquid and food consistencies to evaluate along the edible texture continuum, 3) setting the number of trials to observe for each liquid and food texture administered, and 4) negotiating for the optimum imaging mode (continuous versus pulsed fluoroscopy) for the safe and effective administration of the VFSS (Newman, 2000; Martin-Harris, Logemann, McMahon, Schleicher, & Sandidge, 2000; Peladeau-Pigeon & Steele, 2013) .  In the first part of this series, we’ll explore empirical guidance for consideration of barium administration and the liquid and food consistencies to evaluate along the whole of the liquid and food continuum.  In the second part of this series, we’ll explore the empirical evidence to guide the number of trials to observe for each liquid and food texture and how to negotiate for the optimum imaging mode during the VFSS.    

VFSS Considerations


The VFSS requires barium sulfate products to visualize bolus movement through the upper aerodigestive tract.  Barium sulfate belongs to a class of medications referred to as radiopaque contrast media.  Radiopaque contrast media work by coating the structures of interest with a material that is not absorbed by the body, therefore allowing the areas of interest to be visualized throughout all phases of swallowing. The concentration (density) of barium sulfate varies across products and the concentration (density) of a product is largely dependent on the goals of the exam that utilize the product.  The density of barium is expressed in terms of weight/weight or weight/volume (expressed as a percentage of the weight of barium related to the weight or volume of the suspension) (Foley, Ghahremani, & Rogers, 1982; Dantas, Dodds, Massey & Kern, 1989; Steele, Molfenter, Péladeau-Pigeon, & Stokely, 2013).  

Imaging of the oropharynx requires a low-density concentration of barium, between 20 – 40% weight/volume (Jaffer, Ng, Au, & Steele, 2015; Martin-Harris, Canon, Bonilha, Murray, Davidson, & Lefton-Greif, 2020).  The concentration and physical density of barium contrast material determine its radio-opacity.  Radio-opacity is the relative inability for electromagnetic radiation to pass through the material and it determines how well the contrast material can be seen during the VFSS procedure.  There are different additives present in the barium contrast materials used for radiographic procedures that include emulsifiers, stabilizers, thickeners, and dispersants.  The additives help keep the barium particles suspended in water among other things.  Thickening additives can provide mucosal coating properties, which is undesirable during the VFSS as residue is often a sign of swallowing impairment (Sireci, 2021).  For example, reduced strength of muscular groups responsible for producing closure and positive pressure (squeeze) during the swallow are often identified by the presence of residue in the upper aerodigestive tract during a VFSS.  Barium products that contain thickening agents with mucosal thickening properties will coat anatomic structures and this can be misinterpreted as swallowing pathophysiology (i.e., presence of residue indicates reduced strength of structures).  This is an important reason for SLPs to advocate for the use of standardized barium products that are designed to be used during VFSS (Jaffer, Ng, Au, & Steele, 2015).  

The Varibar® barium sulfate (Bracco Diagnostics Inc., Monroe Twp., NJ) product line is the only barium sulfate contrast media that is FDA-approved for evaluation of dysphagia during the VFSS.  Varibar® products are scientifically designed to have minimal coating properties and their 40% weight/volume density provides optimum opacification across all the consistencies for excellent image quality.  Varibar® makes a full line of VFSS testing materials that range in thickness including: Thin Liquid Barium, Nectar Thick Liquid Barium, Thin Honey Barium, Honey Barium, and Pudding barium (Gosa, Dodrill, & Robbins 2020).  These consistencies were patterned after consistencies that were shown to affect swallowing physiology and mirrored the consistencies advocated for with the National Dysphagia Diet (Felt, 1999).  Varibar® products have since been mapped to the International Dysphagia Diet Standardization Initiative (IDDSI) Framework using the IDDSI syringe flow test (Steele, 2017).  Results were reported as follows:

  • Varibar® Thin Liquid Barium is equivalent to IDDSI Level 0, Thin 
  • Varibar® Nectar Barium is equivalent to IDDSI Level 2, Mildly Thick 
  • Varibar® Thin Honey Barium is equivalent to IDDSI Level 3, Moderately Thick 
  • Varibar® Honey Barium is equivalent to IDDSI Level > 4, Extremely Thick 
  • Varibar® Pudding Barium is equivalent to IDDSI Level > 4, Pureed  

The reader should note that consistencies achieving IDDSI Level > 4 were too thick to flow through the syringe.  These consistencies will require additional testing with additional IDDSI clinical testing methods to further elucidate specific IDDSI level.   

Notably missing from the Varibar® line is a barium sulfate product equivalent to IDDSI Level 1, Slightly Thick.  This consistency was not included in the NDD descriptions.  Slightly Thick is described in the IDDSI framework and it is often used in pediatric populations.  Clinical evidence supports improved swallowing function in infants with change in liquid consistency to the Slightly Thick, IDDSI Level 1 consistency (Gosa, Dodrill, & Robbins 2020).  To create a barium test consistency equivalent to the Slightly Thick, IDDSI Level 1 therapeutic consistency clinicians can do one of the following:

  • Dilute Varibar® Nectar 40% in a 1:1 ratio with water (e.g., 15ml of Varibar® Nectar 40% mixed with 15ml of water)
  • Mix Varibar® Thin 40% Barium Liquid with equal parts Varibar® Nectar 40 (e.g., 15ml of Varibar® Thin 40% Barium Liquid mixed with 15ml of Varibar® Nectar 40%)

These methods of creating a barium test consistency that is equivalent to Slightly Thick, IDDSI Level 1 therapeutic consistency have been confirmed accurate with the IDDSI Syringe Flow Test.  Clinicians should always use clinical testing methods (such as those that support the IDDSI Framework) to confirm that any non-standardized barium products meet the therapeutic consistency parameters that they are targeting (Dodrill and Gosa, 2018).     

The Varibar® barium sulfate (Bracco Diagnostics Inc., Monroe Twp., NJ) product line is only available to clinicians in the United States of America.  Clinicians outside the USA cannot access these specially designed VFSS barium sulfate products.  Even within the USA, there are some clinicians that cannot access the Varibar® line due to facility restrictions and limitations.  All clinicians performing VFSS need access to low concentration barium sulfate suspensions in different thicknesses and consistencies.  In response to this need, the Steele Swallowing Lab has developed an online resource that includes recipes for combining barium sulfate products with water and various thickening agents to achieve specific barium concentrations and consistencies according to the new International Dysphagia Diet Standardization Initiative (IDDSI) Framework (  For further information on this topic, readers are encouraged to read the open access paper by Barbon and Steele (2019) entitled, Characterizing the Flow of Thickened Barium and Non-Barium Liquid Recipes Using the IDDSI Flow Test(                           

Please check out Dr. Gosa and Dr. Suiter’s recent textbook: Assessing and Treating Dysphagia: A Lifespan Perspective (1st Edition)

Consistencies Tested

One goal of the VFSS is to determine the safest way to continue oral intake.  To that end, the clinician must consider introducing a variety of liquids, semisolids, and solid textures during the examination. It is hoped that the boluses introduced during the swallow study reflect the food and liquid consistencies that a patient might encounter during daily oral intake. Clinicians must consider whether it is necessary to test every food, liquid, pill shape and size available in order to make an appropriate recommendation for an oral diet. 

Patients who are already consuming an oral diet often present with complaints regarding their ability to swallow specific liquids, foods, or medications. They may report having specific difficulty swallowing foods or liquids that are certain temperatures, certain tastes, mixed consistencies, or carbonated beverages. Is it necessary to introduce these specific foods or liquids during the swallow study in order to meet the goals of the instrumental swallow study, which are to identify swallow pathophysiology and to identify appropriate treatment strategies if needed? Martin Harris et al. (2020) warned against off-label mixing of barium powders or suspensions with foods and liquids, stating that this practice puts patients at risk because: 1) aspiration of food or liquid rather than barium can threaten the patient’s pulmonary health; 2) mixing foods with barium can alter bolus viscosity; and 3) altering contrast materials may violate food safety regulations and infection control policies of a facility.  

As mentioned previously, barium products, such as Varibar, are available in a variety, albeit a limited variety, of viscosities, meant to represent viscosities and textures in a typical oral diet. Standardized protocols, such as the MBSImP, suggest trialing multiple consistencies, including a range of liquid viscosities, pudding, and a solid texture. Often, VFSS protocol include a thin liquid, a pudding or pureed texture, and a solid without introducing thickened liquids, such as nectar or honey-thick liquids, because those consistencies are not encountered frequently during day-to-day oral intake and because the use of thickened liquids is a management strategy that need not be introduced for patients for whom that management strategy is not needed. 

There is considerable evidence that bolus viscosity and volume affect oropharyngeal swallowing (e.g., Dantas et al., 1990; Inamoto et al., 2013; Hazelwood et al., 2017; Kendall et al., 2001; Lazarus et al., 1993; Lee et al., 2013; Newman et al., 2016; Robbins et al., 1987). It has been documented that presentation of specific bolus volumes and viscosities contribute differentially to overall impressions of swallow impairment (Hazelwood et al, 2017). The question then becomes, if the clinician does not present specific bolus types and volumes during a swallow study, are the results of the study accurate? Conversely, if only certain bolus volumes and viscosities contribute significantly to overall impressions of swallowing impairment, is it necessary to present additional bolus types and viscosities during the VFSS?  Based on current evidence, the authors support the use of a standardized VFSS protocol with representative samples from the food continuum as the safest and most efficacious way to distinguish the anatomic and/or physiologic causes of an individual’s oropharyngeal swallowing impairment across the age continuum. 

Next Steps

What do VFSS look like at your facility?  The next step from any learning activity is to consider the concepts learned within the context of your own clinical practice.  Take inventory of what barium products are being used to complete VFSS at your facility.  Does your facility use Varibar® products? If not, what is the barium concentration of the products used at your facility?  Remember that imaging of the oropharynx requires a low-density concentration of barium, between 20 – 40% weight/volume (Jaffer, Ng, Au, & Steele, 2015; Martin-Harris, Canon, Bonilha, Murray, Davidson, & Lefton-Greif, 2020).  What is the risk to accurate interpretation of oropharyngeal swallowing function if your facility is using higher-density concentrations of barium (higher than 40% weight/volume)?  What liquid and food consistencies are being tested during VFSS at your facility?  Is there a standardized procedure in place?  If not- what is the risk to the patient in terms of accurate identification of swallowing impairment, overly restrictive diet recommendations, and/or excessive exposure to ionizing radiation due to prolonged time in the fluoroscopy suite?  These are important interprofessional conversations to have amongst the SLPs at your facility and with your colleagues in radiology.  

In the second part of this series, we’ll explore the remaining two VFSS considerations: 1) determining the number of trials to observe for each liquid and food consistency tested and 2) negotiating for optimum imaging mode during the VFSS.  It’ll give more food for thought and hopefully expand conversations started at the completion of this first part.  

Co-author Bio:

Debra Suiter is the Director of the Voice and Swallow Clinic and Associate Professor in the Department of Communication Sciences and Disorders. She received a Master’s Degree in Speech Pathology in 1993 and a Doctoral Degree in Speech and Hearing Science in 2001, both from The University of Tennessee-Knoxville. She has worked in a number of clinical service settings, including acute care, acute rehabilitation, long-term care, and outpatient settings. Debra has extensive experience in working with adults with swallowing disorders. She is a Board Certified Specialist in Swallowing and Swallowing Disorders and currently serves on the Boards of the American Board for Swallowing and Swallowing Disorders and the Dysphagia Research Society. Debra’s specialized training includes the evaluation and treatment of swallowing disorders. She works as a member of the multidisciplinary ALS clinic under the direction of Dr. Edward Kasarskis. Additionally, she is a certified provider of Lee Silverman Voice Treatment (LSVT) for treatment of voice changes associated with Parkinson Disease and related disorders. Debra has presented on the topics of swallowing and swallowing disorders at local, national and international conferences and has published the results of her research in a number of peer-reviewed publications. She is also the co-author of a book on The Yale Swallow Protocol that she and Dr. Steven Leder from Yale University School of Medicine developed.

Links of Interest: Please check out Dr. Gosa and Dr. Suiter’s recent textbook: Assessing and Treating Dysphagia: A Lifespan Perspective (1st Edition)


Barbon, C. E., & Steele, C. M. (2019). Characterizing the flow of thickened barium and non-barium liquid recipes using the IDDSI flow test. Dysphagia34(1), 73-79.

Cook, I. J. (2008). Diagnostic evaluation of dysphagia. Nature Clinical Practice Gastroenterology & Hepatology5(7), 393-403.

Dantas, R. O., Dodds, W. J., Massey, B. T., & Kern, M. K. (1989). The effect of high-vs low-density barium preparations on the quantitative features of swallowing. American Journal of Roentgenology153(6), 1191-1195.

Dantas, R. O., Kern, M. K., Massey, B. T., Dodds, W. J., Kahrilas, P. J., Brasseur, J. G., Cook, I. J., & Lang, I. M. (1990). Effect of swallowed bolus variables on oral and pharyngeal phases of swallowing. American Journal of Physiology-Gastrointestinal and Liver Physiology, 258(5), G675-G681.

Dodrill, P., & Gosa, M. M. (2015). Pediatric dysphagia: physiology, assessment, and management. Annals of Nutrition and Metabolism66(Suppl. 5), 24-31.

Dodrill, P. and Gosa, M. (2018). Advances in NICU Feeding Management- Human Patient Simulation, Working with Thickened Feeding Recommendations. April 26-28, 2018; Boston, MA. 

Felt, P. (1999). The national dysphagia diet project: The science and practice. Nutrition in Clinical Practice14, S60-S65.

Foley, M. J., Ghahremani, G. G., & Rogers, L. F. (1982). Reappraisal of contrast media used to detect upper gastrointestinal perforations: comparison of ionic water-soluble media with barium sulfate. Radiology144(2), 231-237.

Gosa, M. M., Dodrill, P., & Robbins, J. (2020). Frontline interventions: Considerations for modifying fluids and foods for management of feeding and swallowing disorders across the life span. American Journal of Speech-Language Pathology29(2S), 934-944.

Hazelwood, R. J., Armeson, K. E., Hill, E. G., Bonilha, H. S., & Martin-Harris, B. (2017). Identification of swallowing tasks from a modified barium swallow study that optimize the detection of physiological impairment. Journal of Speech, Language, and Hearing Research, 60(7), 1855-1863.

Hutcheson, K. A., Barrow, M. P., Barringer, D. A., Knott, J. K., Lin, H. Y., Weber, R. S., & Lazarus, C. L. (2017). Dynamic Imaging Grade of Swallowing Toxicity (DIGEST): scale development and validation. Cancer123(1), 62-70.

Inamoto, Y., Saitoh, E., Okada, S., Kagaya, H., Shibata, S., Ota, K., et al. (2013). The effect of bolus viscosity on laryngeal closure in swallowing: Kinematic analysis using 320-Row area detector CT. Dysphagia, 28(1), 33-42.

Jaffer, N. M., Ng, E., Au, F. W. F., & Steele, C. M. (2015). Fluoroscopic evaluation of oropharyngeal dysphagia: anatomic, technical, and common etiologic factors. American Journal of Roentgenology204(1), 49-58.

Kendall, K. A., Leonard, R. J., & McKenzie, S.W. (2001). Accommodation to changes in bolus viscosity in normal deglutition: A videofluoroscopic swallow study. Annals of Otology, Rhinology, & Laryngology, 110(11), 1059-1065.

Lazarus, C. L., Logemann, J. A., Rademaker, A. W., Kahrilas, P. J., Pajak, T., Lazar, R., & Halper, A. (1993). Effects of bolus volume, viscosity, and repeated swallows in nonstroke subjects and stroke patients. Archives of Physical Medicine and Rehabilitation, 74(10), 1066-1070.

Lee, S., Yoo, J. Y., Kim, M., Ryu, J. S. (2013). Changes of timing variables in swallowing of boluses with different viscosities in patients with dysphagia. Archives of Physical Medicine and Rehabilitation, 94(1), 120-126.

Martin-Harris, B., Logemann, J. A., McMahon, S., Schleicher, M., & Sandidge, J. (2000). Clinical utility of the modified barium swallow. Dysphagia15(3), 136-141.

Martin-Harris, B., Humphries, K., & Garand, K. L. (2017). The modified barium swallow impairment profile (MBSImP™©)–innovation, dissemination and implementation. Perspectives of the ASHA Special Interest Groups2(13), 129-138.

Martin-Harris, B., Canon, C. L., Bonilha, H. S., Murray, J., Davidson, K., & Lefton-Greif, M. A. (2020). Best practices in modified barium swallow studies. American journal of speech-language pathology29(2S), 1078-1093.

Martin-Harris, B., Carson, K. A., Pinto, J. M., & Lefton-Greif, M. A. (2020). BaByVFSSImP© a novel measurement tool for videofluoroscopic assessment of swallowing impairment in bottle-fed babies: establishing a standard. Dysphagia35(1), 90-98.

McGrattan, K. E., McGhee, H. C., McKelvey, K. L., Clemmens, C. S., Hill, E. G., DeToma, A., … & Martin-Harris, B. (2020). Capturing infant swallow impairment on videofluoroscopy: timing matters. Pediatric radiology50(2), 199-206.

Newman, L. A. (2000, November). Optimal care patterns in pediatric patients with dysphagia. In Seminars in Speech and Language (Vol. 21, No. 04, pp. 0281-0292). Copyright© 2000 by Thieme Medical Publishers, Inc., 333 Seventh Avenue, New York, NY 10001, USA. Tel.+ 1 (212) 584-4662.

Newman, R., Vilardell, N., Clave, P., & Speyer, R. (2016). Effect of bolus viscosity on the safety and efficacy of swallowing and the kinematics of the swallow response in patients with oropharyngeal dysphagia: White paper by the European Society for Swallowing Disorders (ESSD). Dysphagia, 31(2), 232-249. 

O’Donoghue, S., & Bagnall, A. (1999). Videofluoroscopic evaluation in the assessment of swallowing disorders in paediatric and adult populations. Folia Phoniatrica et Logopaedica51(4-5), 158-171.

Peladeau-Pigeon, M., & Steele, C. M. (2013). Technical aspects of a videofluoroscopic swallowing study. Can J Speech Lang Pathol Audiol37(3), 216-226.

Robbins, J., Sufit, R., Rosenbek, J., Levine, R., & Hyland, J. (1987). A modification of the modified barium swallow. Dysphagia, 2(2), 83-86.

Salassa, J. (1999). A functional outcome swallowing scale for staging oropharyngeal dysphagia. Digestive Diseases17(4), 230-234.

Schechter, G. L. (1998). Systemic causes of dysphagia in adults. Otolaryngologic Clinics of North America31(3), 525-535.

Sireci, S. (2021).  Clinical utility of barium sulfate products: Formulation determines appropriate use.  Applied Radiology. Available at:

Steele, C. M., Molfenter, S. M., Péladeau-Pigeon, M., & Stokely, S. (2013). Challenges in preparing contrast media for videofluoroscopy. Dysphagia28(3), 464-467.

Steele C. Mapping Bracco’s Varibar® barium products to the IDDSI Framework. June, 2017. Available at: Accessed August 12, 2020.

Tutor, J. D., & Gosa, M. M. (2012). Dysphagia and aspiration in children. Pediatric pulmonology47(4), 321-337.

VARIBAR® THIN LIQUID (barium sulfate) for oral suspension full Prescribing Information. Monroe Twp., NJ: Bracco Diagnostics Inc.; April 2019.