Swallowing assessment in patients with dysphagia: Validity and reliability of a pocket-sized ultrasound system

Abstract

Background: The use of ultrasound as an adjunct to clinical swallowing evaluation provides quantitative physiological and morphological data. As a low-risk procedure, ultrasound imaging can be performed outside of a medical setting. This is particularly important for patients living in rural areas with restricted access to a hospital. Technical advances have produced pocket-sized ultrasound technology that is more affordable, and therefore within the fiscal reach of most allied health services.

Aims: To explore the validity and reliability of pocket-sized ultrasound technology in dysphagia assessment.

Methods & procedures: Data were acquired from 43 patients with dysphagia using the Clarius ultrasound device. Ultrasound and videofluoroscopic measures of hyoid and laryngeal displacement during liquid and puree swallowing were collected concurrently to quantify correlation and agreement between identical measures derived from the two instruments. Reliability of ultrasound was assessed for measures of hyoid and laryngeal displacement, tongue thickness, and size of the submental muscles in eight patients. Reliability was evaluated for the entire process of data acquisition including scanning and online measurement using an iPad in a clinical setting and for offline measurement on a computer screen to explore environmental influences on reliability.

Outcomes & results: Results revealed poor correlation between the measures of interest across instruments. Reliability of the entire process of data acquisition in a clinical setting was insufficient while reliability was more promising for offline measurements.

Conclusions & implications: The clinical use of pocket-sized ultrasound devices, such as the Clarius system, for swallowing evaluation is not indicated at this time. Enhanced validity and reliability of the entire process of data acquisition are needed prior to clinical translation of such technology.

What this paper adds: What is already known on the subject The use of ultrasound allows for radiation-free, non-invasive swallowing assessment. Some data suggest that ultrasound is valid and reliable in the evaluation of swallowing using standard-sized equipment. Insufficient validity and reliability have been reported for pocket-sized ultrasound technology in the assessment of healthy swallowing. What this paper adds to existing knowledge This research is the first to provide validity and reliability data of the pocket-sized Clarius technology in the evaluation of swallowing in patients with dysphagia. Insufficient validity and reliability of online data acquisition in a clinical environment were found. Reliability for offline measurement was more promising. What are the potential or actual clinical implications of this work? The clinical use of pocket-sized ultrasound devices, such as the Clarius system, for swallowing assessment is not indicated at this time.

Keywords: deglutition; dysphagia; reliability; ultrasound; validity; videofluoroscopy.

FIGURE 1

Sonogram of the hyoid in the rest position (a) and at maximal displacement (b) for the assessment of the distance from the hyoid to the mandible (measurement line A). The shadow on the left is cast by the mandible; the shadow on the right is cast by the hyoid [Colour figure can be viewed at wileyonlinelibrary.com]

FIGURE 2

Sonogram of the distance between the hyoid and thyroid cartilage at rest (a) and at maximal approximation (b) with green measurement line D. The shadow on the left is cast by the hyoid; the shadow on the right is cast by the thyroid cartilage [Colour figure can be viewed at wileyonlinelibrary.com]

FIGURE 3

Sonogram of tongue thickness (measurement line D). The shadow on the left is cast by the mandible; the shadow at the right is cast by the hyoid. Lines A and B were drawn to define the measurement point at the lower side of the tongue. The only difference between the two images is that the posterior edge of the bolus on the tongue surface is outlined in red on (b) [Colour figure can be viewed at wileyonlinelibrary.com]

FIGURE 4

Sonogram of the cross‐sectional area (outline T) of the left (a) and right (b) anterior belly of the digastric muscles [Colour figure can be viewed at wileyonlinelibrary.com]

FIGURE 5

Sonogram of the cross‐sectional area of the geniohyoid+ muscles (outline T) [Colour figure can be viewed at wileyonlinelibrary.com]

FIGURE 6

Videofluoroscopic measures of hyoid excursion. Turquoise measurement lines depicting the distance from hyoid to mandible at rest (a) and at maximal hyoid displacement (b). The dark blue drawings at the mandibular prominence were used to define the anterior measurement point [Colour figure can be viewed at wileyonlinelibrary.com]

FIGURE 7

Videofluoroscopic measures of thyrohyoid approximation. Turquoise measurement lines depicting the distance between the hyoid and thyroid cartilage at rest (a) and at maximal approximation (b) [Colour figure can be viewed at wileyonlinelibrary.com]

FIGURE 8

Bland–Altman plot for hyoid excursion during puree swallowing assessed using ultrasound and videofluoroscopy (VFSS). The unit of the x‐ and y‐axes is percentage change. The mean difference between measures of the two instruments is illustrated by the thick dashed red line, with the thin dashed red lines representing the 95% confidence interval. Upper and lower limits of agreement are represented by the thick dashed blue lines, with the 95% confidence intervals represented by the thin blue lines [Colour figure can be viewed at wileyonlinelibrary.com]

FIGURE 9

Bland–Altman plot for thyrohyoid approximation during liquid (a) and puree swallowing (b) assessed using ultrasound and videofluoroscopy (VFSS) [Colour figure can be viewed at wileyonlinelibrary.com]