Purpose: The aim of this study was to establish preliminary reference values for the Visual Analysis of Swallowing Efficiency and Safety (VASES) – a standardized rating methodology used to evaluate swallowing safety and efficiency for flexible endoscopic evaluations of swallowing (FEES).

Method: FEES were completed in non-dysphagic, community-dwelling adults using a standardized protocol of 15 swallowing trials which varied by bolus size, consistency, contrast
agent, and swallowing instructions. FEES were blindly analyzed using VASES. Primary outcome measures included bolus location at swallow onset, Penetration-Aspiration Scale (PAS) scores, and percentage-based residue ratings for six anatomic landmarks. Secondary outcome measures included sip size, bite size, and number of swallows.

Results: Thirty-nine healthy adults completed the study, yielding an analysis of 584 swallows. Swallows were initiated with the bolus in the pharynx for 41.8% of trials. PAS 1 was the most common score, accounting for 75.3% of trials, followed by PAS 3, which accounted for 18.8% of trials. When residue was present (>0%), the amount was relatively small across
all anatomic landmarks, with median residue ratings of 2.0% (oropharynx), 1.5% (hypopharynx), 3.0% (epiglottis), 3.0% (laryngeal vestibule), and 3.5% (vocal folds). Five events of aspiration were observed, which were characterized by subglottic residue ratings of
1%, 3%, 10%, 24%, and 90%. The average sip size of self-selected volume cup sips of water was 19.8 mL and the average bite size of a 3.0-gram saltine cracker was 1.33 grams. Seventy-eight percent of the trials in this study protocol (except 90 mL trials) were completed in a single swallow.

Discussions: The results from this study provide preliminary norms for VASES that could be used as a reference when assessing functional swallowing outcomes during FEES. While this
is an important first step in establishing norms for FEES and VASES, clinicians and researchers should be mindful that the normative reference values from this study are from a relatively small study sample (n = 39), with most people below the age of 60 (n = 30). Future research should expand on these norms by including a greater number of people across the
age continuum and with greater racial, ethnic, and gender diversity.