Normative Reference Values for FEES and VASES: Preliminary Data from 39 Nondysphagic, Community-Dwelling Adults

James A. Curtis, James C. Borders, Avery E. Dakin, and Michelle S. Troche

We were very excited to see this article come out, as those of us at CSP have been following the work of Dr. James Curtis and his VASES project very closely. Before we dive in, let’s briefly review what VASES is.

VASES stands for Visual Analysis of Swallowing Efficiency and Safety and was first introduced in Dysphagia Journal in 2022. There has been a movement in the field of dysphagia to create more standardized approaches to analyzing swallowing. The creation of VASES was to standardize the analysis of laryngeal penetration, aspiration, and pharyngeal residue for FEES. The original paper outlines the following:

    • “What to rate” which includes utilization of the widely accepted Penetration Aspiration Scale (PAS, Rosenbek, 1996) and a new residue rating utilizing landmarks agreed upon by the VASES panel.
    • “Where to rate” by clearly defining landmarks and boundaries for distinguishing laryngeal penetration and aspiration. In our humble opinion this is the BEST part about VASES as previous publications did not have these clearly delineated!
    • “How to rate” which includes a 100-point visual analog scale for quantifying pharyngeal residual and six anatomical regions for analysis.
    • “When to rate” was described for performing PAS (before, during, and after the swallow, as well as between bolus trials). Identifying residual is always performed after the swallow.

Additional secondary rules are outlined in the paper and these are very helpful, even if you are not implementing VASES right away. Dr. Curtis also found that VASES was relatively easy to train novice clinicians to use and feasible (more like “fees”-ible!) for clinical use (taking approximately 1.5 minutes to score each bolus trial). Also, intra-rater reliability was unchanged, yet inter-rater reliability was improved following VASES training. The use of VASES was validated against other rating scales, which was published in the American Journal of Speech Language Pathology in 2022. Subsequent steps involve establishing normative data and examining VASES across multiple patient populations. Which brings us the the paper were are reviewing here.

We highly recommend that you go read this paper. In the meantime, we will give you a summary in hopes that it piques your interest.

Aim:To establish preliminary normative reference values for VASES functional swallowing outcome measures, in addition to typical sip sizes, bite sizes, and number of swallows, across a range of standardized swallowing conditions using convenience sampling of nondysphagic, community-dwelling, healthy adults.”

Methods: This was a prospective study examining 39 community dwelling adults (20 females/19 males) who denied any swallowing deficits via telephone interview. Exclusion criteria included any history of GI, respiratory, or neurologic diseases; head/neck cancer, or any surgery outside of routine procedures involving the head, neck or spine. The group included 8 participants under 40, 20 were aged 40-59, 10 were 60-79, and one was over 80 years old.

Participants underwent a FEES Protocol utilizing 15 swallows including water colored with blue, green, and white food coloring, vanilla pudding with blue food coloring, and a cracker. The protocol included:

  • Two self-selected volume sips of water using an 8 ounce cup
  • Two trials of 5, 10, and 20 ml of water using a medicine cup
  • Two more trials of self-selected volume from 8 oz cup
  • One 90 ml presentation of water uninterrupted
  • Two 5 ml trials of pudding
  • Two self-selected trials of cracker

The FEES recordings were broken into clips for each bolus, resulting in 584 video clips. Of these, 341 were analyzed by paired graduate student raters following completion of VASES training and the remaining 243 were analyzed by Dr. James Curtis.

VASES Outcomes

Bolus Location at Swallow Onset

Location of the bolus was measured at the onset of the “during the swallow phase” based on landmarks determine by VASES. 41.8% of swallows were observed within the endoscopic view and 58.2% were not observed within this plane, therefore were initiated in the oral cavity. Of the 41.8% that were observed, they were noted in the oropharynx in 39.2% of the trials, in the hypopharynx in 14.4%, on the epiglottis for 12%, in the laryngeal vestibule for 1%, and on the vocal folds for 0.2%.

Amount of Pharyngeal Residue, Laryngeal Penetration, and Aspiration

Residue amount was determined using the 0% to 100% scale outlined in the initial VASES paper and identified for those six landmarks. Oropharyngeal residue was present for 94.2% of the swallows. Hypopharyngeal residue was noted in 86.5% of swallows. Epiglottic residue was present for 65.1% of trials. Seems like a lot right? Not really…the amount was estimated to be only about 2%, 1.5%, and 3% respectively. Oddly, residue for both locations was absent most for crackers, then pudding, then thins.

Laryngeal vestibule residue was observed in 31.9% of the water trails and 0% of the pudding or cracker trials with the amount judged to be 3%. Vocal fold residue was observed on water trials only (6.8%) and the amount was estimated to be 3.5%. Subglottic residue was noted for water trials in only 1% of green water (self-selected), 3% of the time for 10 ml of white water, 10% of the time for self-selected white water, 24% of trials for 90 ml of white water and 90% of trials of 10 ml white water.

PAS was utilized using the anatomic and temporal boundaries outlined by VASES (before/during/after swallows or between bolus trials). One clarifying point here: material found on the medial edge of the vocal folds or between the vocal folds did not count as aspiration since it technically did not reach the subglottic region. Four PAS scores were rated for each of the four temporal boundaries. PAS of 1 was the most common score (75.3% of trials), followed by PAS of 3 (18.8%), PAS 5 (4.3%), PAS 7 (0.5%), PAS 8 (0.3%), and 0% for PAS 4 and PAS 6. Only four of the 39 participants did not penetrate or aspirate. Not shocking – we know that normals demonstrate laryngeal penetration and aspiration on the regular! Of note, only five of the penetration/aspiration events occurred outside of the during the swallow timeframe.

Secondary Outcomes

Bolus Size

Self-selected volumes were analyzed by weighing cups after each sip and measuring solids after each bite. The median sips size for self-selected volume cup sips was 19 ml for natural swallows and 17.5 ml when instructions were provided to take “single sips.” The median bolus size for the cracker was a little over 1 gram or approximately one third of the cracker.

Number of Swallows

Swallows were counted based on scope white out periods and audible swallow sounds recorded on FEES. For the single presentations (all trials except 90 ml), 78% of participants swallowed the entire presentation in one swallow, 19.1% completed in two swallows, 2.9% completed in three swallows. More swallows were observed when instructed to take self-selected volumes.


The authors recognized the small sample size as a limitation of the study, as well as the limited age range, cultural and gender diversity, but it certainly is a starting point. Bolus onset findings are fairly consistent with previous research, likely appearing slightly reduced when compared to a less controlled study (Dua, 1997). The small amount of pharyngeal residue found is also similar to previous research utilizing FEES and MBSS. Laryngeal penetration and aspiration was noted more frequently on the present study than on the well known study completed by Dr. Susan Butler from 2018. Dr. Curtis suggested this may be a result of utilizing the white food coloring. We have our own thoughts about white food coloring that are discussed in our FEES training courses, which we may feature in a future blog.

Dr. Curtis goes on to discuss the findings of the amount of airway invasion stating, “nondysphagic, healthy adults may exhibit similar relationships between aspiration amount and the presence of silent versus nonsilent aspiration as has been seen in people with neurological disease, though larger sample sizes are needed.

The number of swallows identified within this study were consistent with previous research. Dr. Curtis mentions that the instruction to take a single sip maybe helpful to minimize the presence of piecemeal deglutition; however, we aren’t sure that we would implement this outside of research. Completing a functional FEES for examining “real life” patients, we try to limit instructions that would change their typical eating/drinking behavior unless we are implementing compensatory techniques. Sip sizes measured in this study appear to be consistent with what has previously been reported.

As discussed in our blog from earlier this month, it is imperative that clinicians understand the wide variances that can occur within healthy swallowers in order to prevent over-diagnosing and inappropriately treating “problems” that are actually within a normal range. Dr. Curtis’s findings strengthen our understanding of normal airway invasion, normal residuals, and normal ranges of bolus size and number of swallows. We look forward to continuing to integrate dysphagia research findings into our practice so that we can best serve our patients and support our fellow SLPs with accurate, reliable FEES analysis and functional recommendations.

Written by Selena Reece, M.S., CCC-SLP, BCS-S
Edited by Lyndsay Parker, M.S., CCC-SLP

Butler SG, Stuart A, Markley L, Feng X, Kritchevsky SB. Aspiration as a Function of Age, Sex, Liquid Type, Bolus Volume, and Bolus Delivery Across the Healthy Adult Life Span. Ann Otol Rhinol Laryngol. 2018 Jan;127(1):21-32. doi: 10.1177/0003489417742161. Epub 2017 Nov 30. PMID: 29188729.

Curtis, J.A., Borders, J.C., Perry, S.E. et al. Visual Analysis of Swallowing Efficiency and Safety (VASES): A Standardized Approach to Rating Pharyngeal Residue, Penetration, and Aspiration During FEES. Dysphagia 37, 417–435 (2022).

Curtis JA, Borders JC, Perry SE, Dakin AE, Seikaly ZN, Troche MS. Visual Analysis of Swallowing Efficiency and Safety (VASES): A Standardized Approach to Rating Pharyngeal Residue, Penetration, and Aspiration During FEES. Dysphagia. 2022 Apr;37(2):417-435. doi: 10.1007/s00455-021-10293-5. Epub 2021 Apr 10. PMID: 33837841.

Curtis JA, Borders JC, Troche MS. Visual Analysis of Swallowing Efficiency and Safety (VASES): Establishing Criterion-Referenced Validity and Concurrent Validity. Am J Speech Lang Pathol. 2022 Mar 10;31(2):808-818. doi: 10.1044/2021_AJSLP-21-00116. Epub 2022 Jan 24. PMID: 35077197.

Dua KS, Ren J, Bardan E, Xie P, Shaker R. Coordination of deglutitive glottal function and pharyngeal bolus transit during normal eating. Gastroenterology. 1997 Jan;112(1):73-83. doi: 10.1016/s0016-5085(97)70221-x. PMID: 8978345.

Rosenbek JC, Robbins JA, Roecker EB, Coyle JL, Wood JL. A penetration-aspiration scale. Dysphagia. 1996 Spring;11(2):93-8. doi: 10.1007/BF00417897. PMID: 8721066.