The ASPEKT Method

The ASPEKT Method (Analysis of Swallowing Physiology: Events, Kinematics and Timing) is a standard operating procedure for quantitative analysis of videofluoroscopy recordings of swallowing in adults.

For more information, please visit each tab below.

Why was the ASPEKT Method developed?

The goal of the ASPEKT Method is to provide clinicians and dysphagia researchers with reference values for healthy swallowing, which will enable them to determine which components of swallowing fall outside the range of values expected in healthy swallowing.

Why is it important to compare patient values to healthy reference values?

There are many situations in clinical medicine where patient values are compared to healthy reference values. Two common examples include:

a) Height and weight charts for children

It is routine to assess growth and nutritional status in infancy, childhood and adolescence (up to 19 years of age) by comparing individual growth measurements against growth data or growth charts from a reference (“normal”) population (a “growth reference” or “growth standard”). Figure 1, below, is a reference chart published by the World Health Organization for weight and height in girls up to age 5 years. By comparing the height and weight of a girl to this chart, a clinician or parent can understand whether the child is relatively tall or of typical weight for their age.

Figure 1. WHO Child Growth Standards Weight-for-age: Birth to 5 years percentiles chart for girls.
Source: http://www.who.int/childgrowth/standards/chts_wfa_girls_p/en/

b) Interpreting blood test results

When a blood sample is sent to a lab, the goal is to compare the values of various components of the blood sample to healthy reference values, to understand whether or not there is a problem. For example, a test might determine whether a person has sufficient iron or is anemic, whether they have high or low sodium or potassium, whether they have an adequate number of red blood cells, hemoglobin or platelets, or whether they have higher-than-usual numbers of white blood cells suggesting infection. Reference tables that are used for interpreting blood tests and other laboratory tests in Canada can be found at: https://mcc.ca/objectives/normal-values/?cn-reloaded=1.

What is the definition of the “Healthy Reference Interval”?

The “Healthy Reference Interval” is a statistical term referring to the most-common 95% of values seen in the healthy reference population. For parameters that have a bell-shaped normal (or Gaussian) distribution, these values fall between the 2.5th percentile and the 97.5th percentile, or within 2 standard deviations on either side of the mean, as shown in Figure 2.

Figure 2. Illustration of the boundaries of the healthy reference interval on a Gaussian shaped distribution

For parameters that have skewed distributions, the reference interval is defined either as the interval below the 95th percentile (p95) or above the 5th percentile (p5), depending on the direction of the skew. Figure 3 illustrates a positively skewed parameter:

Figure 3. Illustration of the boundaries of the healthy reference interval for a positively skewed parameter.

Determining “Clinical Decision Points”

Although it is statistically accurate to consider values outside the healthy reference interval (i.e., the 5% of data in the tail(s) of the distribution) as “abnormal”, or “extreme”, we need to consider whether or not the boundaries of the reference interval, are good boundaries for deciding whether or not somebody has a value of clinical concern. The answer here is not necessarily.  In fact, using the boundaries of the reference interval for this purpose is probably too stringent because values in healthy people and values in people who genuinely have a clinical condition of concern are likely to overlap to some degree. Thresholds used to identify values of potential clinical concern are called “Clinical Decision Points” and they are often set at values that approach but do not reach the boundaries of the reference interval. For example, the upper boundary of the reference interval for measures of fasting blood glucose in healthy adults is ≥ 6 mmol/L (with some variations in exactly where this line falls due to age, sex and body mass index). However, the clinical decision point that is used as the clinically accepted value for triggering concern and diagnosing a patient with “prediabetes” is ≥ 5.6 mmol/L.

When it comes to swallowing, we don’t yet have enough data to set clinical decision points with confidence, but we believe that there is probably value in proposing clinical decision points at points along the distribution that are less extreme than the boundaries of the reference interval. Therefore, we propose using the term “typical” to describe values that fall in the central 50% of the healthy data distribution, and “atypical” for all values that fall outside that range, either below the 25th or above the 75th percentile.  “Atypical” values include values that are truly extreme, in the tails of the distribution, and also values that are approaching those tails. If we are looking at a skewed parameter, would be clinically interested in only one side of the distribution rather than “atypical” values on both sides.  In Figure 4 below, we use traffic light colour coding to represent typical values on a bell-shaped normal distribution in green-shaded areas and to divide the atypical ranges into red-coloured extreme values and amber-coloured values outside the typical range, but approaching the boundaries of the reference interval.

Figure 4. Illustration of clinical decision points set at the 25th and 75th percentile values of a Gaussian distribution, distinguishing typical from atypical values.

Figure 5 shows an analogous image for a positively skewed distribution:

Figure 5. Illustration of a clinical decision point set at the 75th percentile of a positively skewed distribution, distinguishing typical from atypical values.

What are the steps involved in the ASPEKT Method?

The ASPEKT Method is a process for analyzing swallowing at the single bolus level. The steps for analyzing a single bolus are as follows:

    1. The bolus clip is reviewed and the number of swallows for that bolus are counted. A swallow is defined as an event in which bolus material passes through the upper esophageal sphincter (UES).
    2. Swallowing safety is rated for each swallow using the 8-point Penetration-Aspiration Scale (Rosenbek et al., 1996).

ALL remaining steps of the ASPEKT Method are performed for the initial swallow of the bolus only:

    1. The integrity of laryngeal vestibule closure (LVC) is recorded as complete, partial or incomplete.
    2. The frame numbers for a series of key events are documented:
      • Bolus passing mandible (BPM)
      • Onset of the Hyoid Burst (HYB)
      • The first frame of Upper Esophageal Sphincter opening (UESO)
      • The first frame of most-complete laryngeal vestibule closure (LVC)
      • The frame of maximum UES diameter
      • Peak antero-superior (XY) hyoid position
      • Maximum pharyngeal constriction
      • UES Closure behind the bolus
      • LVC Closure behind the bolus
      • Swallow Rest
    3. Timing measures are calculated based on the interval (i.e., number of frames) between key events.
    4. Anatomically-referenced pixel-based measures are performed as follows:
      • Hyoid position (X, Y and XY) is measured relative to the anterior-inferior corner of the C4 vertebra, in a coordinate system with the y-axis defined by a line running between the anterior-inferior corners of the C2 and C4 vertebrae (and the x-axis derived perpendicular to the y-axis). Hyoid position measures are normalized to a cervical spine scalar defined as the length of the line running between the anterior-inferior corners of the C2 and C4 vertebrae, i.e., %(C2-4).
        • Hyoid XY Speed is calculated by calculating the difference in hyoid position between the frames of Peak XY Hyoid Position and Hyoid Burst Onset and dividing this distance by the interval between the frames of Peak XY Hyoid Position and Hyoid Burst Onset.
      • Maximum UES Diameter is measured and normalized to the C2-C4 scalar reference, i.e., %(C2-4).
      • Pharyngeal area at rest (PhAR) is measured as follows:
        • The C2-4 reference scalar is measured, defined as the distance (in pixels) between the anterior-inferior corners of the C2 and C4 vertebrae;
        • A second line, perpendicular to the C2-C4 scalar reference is then drawn and moved upwards, to align with the anterior-superior corner of the C2 vertebra;
        • The area of unobliterated pharyngeal space is traced (including both air and any visible bolus material) between the following boundaries: superiorly, the top of the C2 vertebra; posteriorly, the posterior pharyngeal wall; inferiorly, the pit of the pyriform sinuses; and anteriorly, the base of tongue, pharyngeal surface of the epiglottis, aryepiglottic folds and anterior wall of the pyriform sinus;
        • The pharyngeal area measure is converted into %(C2-4)2 units by dividing the area measure by the (C2-4)2 reference scalar and multiplying by 100%.
      • Pharyngeal area is measured on the frame of maximum pharyngeal constriction (PhAMPC) using the same procedures described above for measures of pharyngeal area at rest.
      • Residue area is measured in the valleculae, pyriform sinuses and elsewhere in the pharynx and normalized to the squared length of the C2-C4 scalar reference, i.e., %(C2-4)2. Residue measures may be summed across these locations for a composite measure of Total Pharyngeal Residue.

Which parameters are included in the ASPEKT Method?

The ASPEKT Method includes the following swallowing parameters:

    • Number of swallows per bolus
    • Penetration-Aspiration measured using the 8-point Penetration-Aspiration Scale (Rosenbek et al., 1996)
    • Laryngeal Vestibule Closure (LVC) Integrity (i.e., complete, partial or incomplete closure)

Timing Measures:

    • Swallow Reaction Time (SRT: i.e., the interval between the frame of the bolus passing the mandible and onset of the hyoid burst)`
    • Hyoid Burst to UES Opening interval (HYB-UESO: i.e., the interval between onset of the hyoid burst and the first frame of upper esophageal sphincter opening)
    • UES Opening Duration (UESO Dur: i.e., the interval between the first frame of upper esophageal sphincter opening and the first frame of upper esophageal sphincter closure behind the bolus)
    • Time-to-LVC (TTLVC: i.e., the interval between onset of the hyoid burst and the first frame of most complete LVC)
    • LVC duration (LVC Dur: i.e., the interval between the first frame of most complete laryngeal vestibule closure and the offset of LVC)

Pixel-based Measures*:

*All pixel based measures are expressed in anatomically normalized values, relative to the length of a line running from the anterior inferior corner of the C2 vertebra to the anterior inferior corner of the C4 vertebra, and measured in a coordinate space with the y-axis aligned with the C2-C4 cervical spine and the x-axis defined perpendicular to the cervical spine. Single-dimension length or position measures are expressed in %(C2-4) units. Two-dimension area measures are expressed in %(C2-4)2 units. In the event that the cervical spine cannot be properly visualized or there is surgical hardware, which may invalidate the scalar reference measure, two times the length of the vocal fold process may be used as an alternative scalar.

    • Pharyngeal area at Rest (PhAR)
    • UES Opening Diameter
    • Pharyngeal Area at Maximum Pharyngeal Constriction (PhAMPC)
    • Vallecular Residue
    • Pyriform Sinus Residue
    • Other Pharyngeal Residue
    • Total Pharyngeal Residue
    • Hyoid Peak Position (X, Y and XY coordinates, relative to the anterior inferior corner of the C4 vertebra)
    • Hyoid XY Speed (i.e., the difference in XY hyoid position between the frame of hyoid burst onset and the frame of peak hyoid position, divided by the duration of the hyoid burst to hyoid peak position interval)

Which parameters are no longer part of the ASPEKT Method?

In the original 2019 Reference Values publication, we reported on the following parameters, which are no longer part of the ASPEKT Method:

    • Bolus Location at Swallow Onset & Bolus Location at Laryngeal Vestibule Closure: These parameters were found to vary widely across healthy individuals and are not considered informative in terms of swallowing pathophysiology.
    • The Normalized Residue Ratio Scale (Pearson et al. , 2013): The Normalized Residue Ratio Scale (NRRS) expresses residue as a percent of housing area (either the valleculae or pyriform sinuses), as viewed on a lateral view videofluoroscopic image, and normalizes this ratio to a cervical spine scalar. As discussed in a subsequent publication, the estimate of spatial housing area used in the NRRS is questionably valid. Instead, the ASPEKT Method reports residue in %(C2-4)2 units. This approach has the added benefit of enabling the summation of total pharyngeal residue by adding together residue measurements from the valleculae, pyriform sinuses and elsewhere in the pharynx.

Measurement of Peak Hyoid Position

For more information about measurement of peak hyoid position, click here.

Does the ASPEKT Method require use of a specific videofluoroscopy testing protocol?

No. The ASPEKT Method is an analysis method that is applied at the bolus level. Please see additional information below regarding the methods used during data collection for the ASPEKT Method Reference Values.

Do the ASPEKT Method Reference Values apply to all bolus consistencies?

ASPEKT Method Reference Values are available for thin, slightly thick, mildly thick, moderately thick and extremely thick liquid consistencies, as defined by the International Dysphagia Diet Standardisation Initiative (https://www.iddsi.org).

What kind of barium was used for collecting the ASPEKT Method Reference Values?

The ASPEKT Method Reference Values were collected using Bracco E-Z-Paque powdered barium prepared in a 20% w/v concentration with Nestle Pure Life bottled water. Thickened consistencies were prepared by adding Resource ThickenUp Clear xanthan gum thickener (Nestle Health Science) to the 20% w/v concentration thin liquid E-Z-Paque solution. For more information about barium recipes, please visit: https://steeleswallowinglab.ca/srrl/best-practice/barium-recipes/

What other methodological considerations were controlled during collection of the ASPEKT Method Reference Values data?

  • Sip size: The ASPEKT Method Reference Values data were collected using comfortable natural sips of thin, slightly thick and mildly thick barium and comfortable teaspoon-delivered boluses of moderately thick and extremely thick barium.
  • Cued vs Non-Cued Swallows: Research participants self-administered these boluses and were instructed to swallow when they felt ready, without waiting for a cue.
  • Frame Rate: All swallows were captured using pulsed fluoroscopy at a rate of 30 pulses per second and recorded at a rate of 30 frames per second.

Who can use the ASPEKT Method?

The ASPEKT Method can be used either by clinicians or dysphagia researchers.

Is the ASPEKT Method Licensed?

The ASPEKT Method (Analysis of Swallowing Physiology: Events, Kinematics and Timing) by https://steeleswallowinglab.ca is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

Do I need specific training in order to use the ASPEKT Method?

A number of public domain resources are available explaining and illustrating use of the ASPEKT Method. For research use, we recommend official training and certification. To obtain more information regarding training and certification, please send an email to tri-swallowinglab@uhn.ca.

Resources Available File Link
2023 Manuscript and Reference Tables Link
2023 Manuscript Key takeaways Link
2019 Webinar Link
2019 Q&A session Link

Is it permitted to use single parameter(s) or must the ASPEKT Method be used in full?

Researchers or clinicians are permitted to use and report single or multiple parameters from the ASPEKT Method in their work. When doing so, this should be described as reporting the specific parameter name, as defined by the ASPEKT Method. It is incorrect to refer to a single parameter as the ASPEKT Method. Clinicians may also prefer to explore use of the ASPEKT-C Method (the clinical version of the ASPEKT Method).

Are users allowed to adapt or modify the ASPEKT Method?

No. The ASPEKT Method is covered by a Creative Commons Attribution-ShareAlike 4.0 International License.

  • Attribution is requested as follows: © ASPEKT Method (Analysis of Swallowing Physiology: Events, Kinematics and Timing) by https://steeleswallowinglab.ca.
  • The ASPEKT Method must be used and attributed without modification to the terminology, abbreviations or definitions of the ASPEKT Method, parameters and reference values. Derivative works extending beyond language translation are NOT PERMITTED. Researchers who wish to explore official translations of the ASPEKT Method into languages other than English are asked to contact Professor Steele at tri-swallowinglab@uhn.ca.
  • Researchers or clinicians who wish to include other parameters or terminology in their work must clearly identify these parameters as measures that are not part of the ASPEKT Method.

Where can I find research using the ASPEKT Method?
The table below provides links to research from our lab using the ASPEKT Method. Many of the links lead to open access copies of the associated manuscript. To access copies of papers that are not open access, please send an email request to tri-swallowinglab@uhn.ca.

ASPEKT Method Publications File Link
Manuscript (2019) – Healthy Individuals Aged Under 60 Link
Manuscript (2020) – Chronic Obstructive Pulmonary Disease Link
Manuscript (2020) – Review of residue measurement methods Link
Manuscript (2020) – Risk of penetration-aspiration related to residue Link
Manuscript (2020) – Post-radiation Oropharyngeal Cancer Link
Manuscript (2020) – Amyotrophic Lateral Sclerosis Link
Manuscript (2021) – Age effects on swallowing (Thin liquid only) Link
Manuscript (2021) – Hyoid parameters in healthy adults Link
Manuscript (2021) – The effect of bolus consistency on penetration-aspiration in individuals with dysphagia following radiation for oropharyngeal cancer Link
Manuscript (2022) – Parkinson Disease Link
Manuscript (2022) – Mechanisms of impaired swallowing safety Link
Manuscript (2022) – Variations in swallowing related to barium product and concentration Link
Manuscript (2022) – Profiles of swallowing impairment after unilateral supratentorial ischemic stroke Link
Manuscript (2023) – Swallow timing comparison in healthy adults, individuals with Parkinson Disease and individuals with Amyotrophic Lateral Sclerosis Link
Manuscript (2023) – Traumatic Spinal Cord Injury Link
Manuscript (2023) – Pharyngeal Area at Rest in healthy adults Link
Manuscript (2023) – Reference Values for Videofluoroscopic Measures of Swallowing: An Update Link
(key takeaways)

The ASPEKT Method (Analysis of Swallowing Physiology: Events, Kinematics and Timing) by https://steeleswallowinglab.ca is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.