Examining swallowing parameters of the Yale Swallow Protocol in healthy individuals: Establishing Normative Data

Currently, the Yale Swallow Protocol overidentifies prandial aspiration. The current investigation aimed to establish normative data for the number of swallows, average volume per swallow, time to complete, and integrated surface electromyography signal (area under the curve) for the consumption of 3 oz (90 mL) of water.

Participants were divided into three groups: younger adults (n = 65, = 22.8 years), middle-aged adults (n = 62, = 53.2 years), and older adults (n = 65, = 81.5 years). Participants consumed 3 oz (90 mL) of water while connected to a surface electromyography device. Descriptive statistics and the main effects of age were computed.

Data for the number of swallows, average volume per swallow, time to complete, and integrated surface electromyography signal (area under the curve) were reported. For the 3-oz (90 mL) task, the number of swallows consistently increased as age increased. Younger and middle-aged adults consumed 3 oz of water with a statistically significant fewer number of swallows when compared to older adults (younger p = 0.008 and middle-aged p = 0.017). Although it did not reach statistical significance, younger adults swallowed fewer times than middle-aged adults (p = 0.822). The average volume per swallow decreased as age increased. Although younger and middle-aged adults consumed similar average volumes per swallow, younger adults swallowed a statistically significant greater average amount per swallow than older adults (p = 0.001) as did middle-aged adults (p = 0.001). The time to complete increased as age increased. Although there were no statistically significant differences between younger and middle-aged adults, older adults took significantly more time to consume 3 oz of water than middle-aged adults (p = 0.004) and younger adults (p = 0.001). The middle-aged adults had the smallest, and younger adults had the largest area under the curve. There were significant differences between younger and middle-aged adults (p = 0.004) and middle-aged and older adults (p = 0.043).

The study provided normative data for number of swallows, average volume per swallow, time to complete, and integrated surface electromyography signal or area under the curve while consuming 3 oz (90 mL) of water. Data from the current study provides a foundation for future research to examine the sensitivity and specificity of the YSP using additional parameters.