Trial Outcomes & Findings for Physiological Flow of Liquids in Healthy Swallowing (NCT NCT04114617)

NCT ID: NCT04114617

Last Updated: 2022-12-21

Results Overview

Swallowing safety was measured using the Penetration-Aspiration Scale, an 8-point categorical scale which captures the depth to which any material enters the airway and whether or not the material is ejected. Levels 1 and 2 on the scale are considered safe, while levels \> 2 are considered unsafe. Actual scale scores (1-8) will be recorded and then converted to binary categorical scores (\< 3 vs \>/= 3). We will report the frequency (count) of participants showing scores \> 2 by bolus consistency.

• Recruitment status: COMPLETED
• Target enrollment: 80 participants
• Primary outcome timeframe: Baseline (single timepoint only)
• Results posted on: 2022-12-21

Participant Flow

Participant milestones

Measure	Healthy Swallowing of Various Consistencies of Liquid Barium Healthy adults (without any history or complaints of swallowing impairment) were asked to swallow comfortable sips of different consistencies of liquid barium (thin, slightly thick, mildly thick, moderately thick, extremely thick). Consistencies were defined according to the International Dysphagia Diet Standardisation Initiative Framework. Each participant took 3 sips of each consistency and swallowed without a cue from the investigator.
Overall Study STARTED	80
Overall Study COMPLETED	80
Overall Study NOT COMPLETED	0

Reasons for withdrawal

Withdrawal data not reported

Baseline Characteristics

Physiological Flow of Liquids in Healthy Swallowing

Baseline characteristics by cohort

Measure	Healthy Adults n=80 Participants Healthy adults aged 18-82.
Age, Continuous	46 years n=5 Participants
Sex: Female, Male Female	42 Participants n=5 Participants
Sex: Female, Male Male	38 Participants n=5 Participants
Ethnicity (NIH/OMB) Hispanic or Latino	3 Participants n=5 Participants
Ethnicity (NIH/OMB) Not Hispanic or Latino	77 Participants n=5 Participants
Ethnicity (NIH/OMB) Unknown or Not Reported	0 Participants n=5 Participants
Race (NIH/OMB) American Indian or Alaska Native	1 Participants n=5 Participants
Race (NIH/OMB) Asian	14 Participants n=5 Participants
Race (NIH/OMB) Native Hawaiian or Other Pacific Islander	1 Participants n=5 Participants
Race (NIH/OMB) Black or African American	3 Participants n=5 Participants
Race (NIH/OMB) White	61 Participants n=5 Participants
Race (NIH/OMB) More than one race	0 Participants n=5 Participants
Race (NIH/OMB) Unknown or Not Reported	0 Participants n=5 Participants
Region of Enrollment Canada	80 participants n=5 Participants

PRIMARY outcome

Timeframe: Baseline (single timepoint only)

Population: A sample of 80 adults was enrolled. Due data quality issues, partial data were missing for thin liquid for 4 participants, and for 3 participants for the remaining consistencies.

Swallowing safety was measured using the Penetration-Aspiration Scale, an 8-point categorical scale which captures the depth to which any material enters the airway and whether or not the material is ejected. Levels 1 and 2 on the scale are considered safe, while levels > 2 are considered unsafe. Actual scale scores (1-8) will be recorded and then converted to binary categorical scores (< 3 vs >/= 3). We will report the frequency (count) of participants showing scores > 2 by bolus consistency.

Outcome measures

Measure	Thin Liquid Barium n=76 Participants Participants were asked to take a series of 3 comfortably sized sips of thin liquid barium (Bracco E-Z-Paque powder) prepared in a 20% w/v concentration with water, and to swallow each sip when ready (without a cue).	Slightly Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized sips of slightly thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to swallow when ready (without a cue).	Mildly Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized sips of mildly thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to swallow when ready (without a cue).	Moderately Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized boluses of moderately thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to self-administer a comfortable bolus using a teaspoon and swallow when ready (without a cue).	Extremely Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized boluses of extremely thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to self-administer a comfortable bolus using a teaspoon and swallow when ready (without a cue).
Number of Participants With Unsafe Swallowing	7 Participants	1 Participants	3 Participants	0 Participants	0 Participants

PRIMARY outcome

Timeframe: Baseline (single timepoint only)

Population: A sample of 80 adults was enrolled. Due to data quality issues, data were missing for 4 participants for thin liquid barium and for 3 participants for the remaining consistencies.

Residue is material remaining behind in the pharynx after the swallow. We measured residue by tracing the area of barium visible on a lateral view x-ray (in pixels, using ImageJ software) and dividing that area by the squared length C2-C4 cervical spine. This cervical spine scalar provides a common anatomical reference that is a proxy for pharyngeal size, and enables the comparison of residue severity across different people with different neck length and pharynx size. In healthy swallowing, residue is expected to be minimal. We report median values and 97.5% confidence intervals for amount of residue by consistency (thin, slightly thick, mildly thick, moderately thick and extremely thick liquids).

Outcome measures

Measure	Thin Liquid Barium n=76 Participants Participants were asked to take a series of 3 comfortably sized sips of thin liquid barium (Bracco E-Z-Paque powder) prepared in a 20% w/v concentration with water, and to swallow each sip when ready (without a cue).	Slightly Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized sips of slightly thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to swallow when ready (without a cue).	Mildly Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized sips of mildly thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to swallow when ready (without a cue).	Moderately Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized boluses of moderately thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to self-administer a comfortable bolus using a teaspoon and swallow when ready (without a cue).	Extremely Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized boluses of extremely thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to self-administer a comfortable bolus using a teaspoon and swallow when ready (without a cue).
Amount of Residue in the Pharynx	0.2 % of the (C2-4)squared scalar reference Interval 0.0 to 4.5	0.3 % of the (C2-4)squared scalar reference Interval 0.0 to 5.1	0.6 % of the (C2-4)squared scalar reference Interval 0.0 to 5.3	0.2 % of the (C2-4)squared scalar reference Interval 0.0 to 4.3	0.1 % of the (C2-4)squared scalar reference Interval 0.0 to 4.2

PRIMARY outcome

Timeframe: Baseline (single timepoint only)

Population: A sample of 80 adults was enrolled. Due data quality issues, partial data were missing for thin liquid for 4 participants, and for 3 participants for the remaining consistencies.

The number of swallows needed to clear a single bolus will be counted. 1-2 swallows is considered efficient, while > 2 for a single bolus is considered inefficient. We report the frequency (count) of participants displaying > 2 swallows per bolus by consistency.

Outcome measures

Measure	Thin Liquid Barium n=76 Participants Participants were asked to take a series of 3 comfortably sized sips of thin liquid barium (Bracco E-Z-Paque powder) prepared in a 20% w/v concentration with water, and to swallow each sip when ready (without a cue).	Slightly Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized sips of slightly thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to swallow when ready (without a cue).	Mildly Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized sips of mildly thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to swallow when ready (without a cue).	Moderately Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized boluses of moderately thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to self-administer a comfortable bolus using a teaspoon and swallow when ready (without a cue).	Extremely Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized boluses of extremely thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to self-administer a comfortable bolus using a teaspoon and swallow when ready (without a cue).
Number of Participants Displaying More Than 2 Swallows Per Bolus	6 Participants	2 Participants	2 Participants	3 Participants	3 Participants

PRIMARY outcome

Timeframe: Baseline (single timepoint only)

Population: A sample of 80 adults was enrolled. Due to data quality issues, data were missing for 4 participants on thin liquid and for 3 participants on the other consistencies.

The time interval between the first frame showing the bolus entering the pharynx (passing the ramus of the mandible) and the first frame showing onset of the hyoid burst movement in swallowing, calculated in milliseconds. We report median values and 97.5% confidence intervals for each bolus consistency (thin, slightly thick, mildly thick, moderately thick and extremely thick liquid barium). Longer time intervals reflect delays in initiating the pharyngeal swallow.

Outcome measures

Measure	Thin Liquid Barium n=76 Participants Participants were asked to take a series of 3 comfortably sized sips of thin liquid barium (Bracco E-Z-Paque powder) prepared in a 20% w/v concentration with water, and to swallow each sip when ready (without a cue).	Slightly Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized sips of slightly thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to swallow when ready (without a cue).	Mildly Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized sips of mildly thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to swallow when ready (without a cue).	Moderately Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized boluses of moderately thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to self-administer a comfortable bolus using a teaspoon and swallow when ready (without a cue).	Extremely Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized boluses of extremely thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to self-administer a comfortable bolus using a teaspoon and swallow when ready (without a cue).
Duration of the Time Interval Between the Bolus Entering the Pharynx and Onset of the Pharyngeal Swallow ("Swallow Reaction Time")	133 milliseconds Interval -33.0 to 967.0	133 milliseconds Interval -67.0 to 934.0	167 milliseconds Interval -33.0 to 1301.0	267 milliseconds Interval -67.0 to 1468.0	367 milliseconds Interval -67.0 to 1701.0

PRIMARY outcome

Timeframe: Baseline (single timepoint only)

Population: A sample of 80 adults was enrolled. Due to data quality issues, data were missing for 4 participants on thin liquid and for 3 participants on the remaining consistencies.

The time interval between the first frame showing onset of the hyoid burst movement in swallowing and the first frame showing opening of the upper esophageal sphincter, calculated in milliseconds. We report median values and 97.5% confidence intervals for each bolus consistency (thin, slightly thick, mildly thick, moderately thick and extremely thick liquid barium). Longer time intervals reflect a delay in opening of the upper esophageal sphincter.

Outcome measures

Measure	Thin Liquid Barium n=76 Participants Participants were asked to take a series of 3 comfortably sized sips of thin liquid barium (Bracco E-Z-Paque powder) prepared in a 20% w/v concentration with water, and to swallow each sip when ready (without a cue).	Slightly Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized sips of slightly thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to swallow when ready (without a cue).	Mildly Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized sips of mildly thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to swallow when ready (without a cue).	Moderately Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized boluses of moderately thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to self-administer a comfortable bolus using a teaspoon and swallow when ready (without a cue).	Extremely Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized boluses of extremely thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to self-administer a comfortable bolus using a teaspoon and swallow when ready (without a cue).
Duration of the Time Interval Between Onset of the Hyoid Burst and Opening of the Upper Esophageal Sphincter	100 milliseconds Interval 33.0 to 200.0	133 milliseconds Interval 33.0 to 200.0	133 milliseconds Interval 33.0 to 234.0	167 milliseconds Interval 67.0 to 267.0	167 milliseconds Interval 67.0 to 267.0

PRIMARY outcome

Timeframe: Baseline (single timepoint only)

Population: A sample of 80 adults was enrolled. Due to data quality issues, data were missing for 4 participants on thin liquid and for 3 participants on the remaining consistencies.

The time interval between the first frame showing opening of the upper esophageal sphincter and the first subsequent frame showing closure of the upper esophageal sphincter behind the tail of the bolus, calculated (in milliseconds). We report median values and 97.5% confidence intervals for each bolus consistency (thin, slightly thick, mildly thick, moderately thick and extremely thick liquid barium). Shorter durations of upper esophageal sphincter opening reflect inadequate durations of opening to allow material to pass through the sphincter from the pharynx into the esophagus.

Outcome measures

Measure	Thin Liquid Barium n=76 Participants Participants were asked to take a series of 3 comfortably sized sips of thin liquid barium (Bracco E-Z-Paque powder) prepared in a 20% w/v concentration with water, and to swallow each sip when ready (without a cue).	Slightly Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized sips of slightly thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to swallow when ready (without a cue).	Mildly Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized sips of mildly thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to swallow when ready (without a cue).	Moderately Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized boluses of moderately thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to self-administer a comfortable bolus using a teaspoon and swallow when ready (without a cue).	Extremely Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized boluses of extremely thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to self-administer a comfortable bolus using a teaspoon and swallow when ready (without a cue).
Duration of Upper Esophageal Sphincter Opening	467 milliseconds Interval 400.0 to 634.0	467 milliseconds Interval 334.0 to 634.0	467 milliseconds Interval 334.0 to 634.0	400 milliseconds Interval 300.0 to 534.0	400 milliseconds Interval 300.0 to 534.0

PRIMARY outcome

Timeframe: Baseline (single timepoint only)

Population: A sample of 80 adults was enrolled. Due to data quality issues, data were missing for 4 participants on thin liquid and for 3 participants on the remaining consistencies.

The time interval between the first frame showing onset of the hyoid burst movement in swallowing and the first frame showing closure of the laryngeal vestibule, calculated in milliseconds. We report median values and 97.5% confidence intervals for each bolus consistency (thin, slightly thick, mildly thick, moderately thick and extremely thick liquid barium). Longer time intervals reflect delays in achieving airway closure.

Outcome measures

Measure	Thin Liquid Barium n=76 Participants Participants were asked to take a series of 3 comfortably sized sips of thin liquid barium (Bracco E-Z-Paque powder) prepared in a 20% w/v concentration with water, and to swallow each sip when ready (without a cue).	Slightly Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized sips of slightly thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to swallow when ready (without a cue).	Mildly Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized sips of mildly thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to swallow when ready (without a cue).	Moderately Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized boluses of moderately thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to self-administer a comfortable bolus using a teaspoon and swallow when ready (without a cue).	Extremely Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized boluses of extremely thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to self-administer a comfortable bolus using a teaspoon and swallow when ready (without a cue).
Duration of the Time Interval Between Onset of the Pharyngeal Swallow and Closure of the Entrance to the Airway ("Time-to-Laryngeal-Vestibule-Closure")	133 milliseconds Interval 33.0 to 267.0	133 milliseconds Interval -100.0 to 167.0	133 milliseconds Interval -33.0 to 367.0	167 milliseconds Interval 0.0 to 300.0	133 milliseconds Interval 33.0 to 267.0

PRIMARY outcome

Timeframe: Baseline (single timepoint only)

Population: A sample of 80 adults was enrolled. Due to data quality issues, data were missing for 4 participants for thin liquid and for 3 participants for the remaining consistencies.

The time interval between the first frame showing closure of the entrance to the airway (laryngeal vestibule closure onset) and the first subsequent frame showing opening of the entrance to the airway (laryngeal vestibule closure offset) calculated in milliseconds. We report median values and 97.5% confidence intervals for each bolus consistency (thin, slightly thick, mildly thick, moderately thick and extremely thick liquid barium). Shorter durations of laryngeal vestibule closure reflect premature termination of airway protection.

Outcome measures

Measure	Thin Liquid Barium n=76 Participants Participants were asked to take a series of 3 comfortably sized sips of thin liquid barium (Bracco E-Z-Paque powder) prepared in a 20% w/v concentration with water, and to swallow each sip when ready (without a cue).	Slightly Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized sips of slightly thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to swallow when ready (without a cue).	Mildly Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized sips of mildly thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to swallow when ready (without a cue).	Moderately Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized boluses of moderately thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to self-administer a comfortable bolus using a teaspoon and swallow when ready (without a cue).	Extremely Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized boluses of extremely thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to self-administer a comfortable bolus using a teaspoon and swallow when ready (without a cue).
Laryngeal Vestibule Closure Duration	467 milliseconds Interval 300.0 to 934.0	467 milliseconds Interval 300.0 to 767.0	467 milliseconds Interval 300.0 to 734.0	434 milliseconds Interval 300.0 to 734.0	434 milliseconds Interval 334.0 to 634.0

PRIMARY outcome

Timeframe: Baseline (single timepoint only)

Population: A sample of 80 adults was enrolled. Due to data quality issues, data were missing for thin liquid in 4 participants, and for the remaining consistencies in 3 participants.

During swallowing, the muscles of the pharynx contract to achieve constriction (closure) of the pharynx behind the bolus. The squeezing and pressure generated by this action help to move the bolus downwards through the pharynx. We measured the degree of pharyngeal constriction by identifying the frame of greatest pharyngeal constriction, and tracing the area of any unobliterated pharyngeal space on lateral view x-ray (in pixels, using ImageJ software). The resulting area measure was then divided by the squared length of the C2-C4 cervical spine. This cervical spine scalar provides a common anatomical reference that is a proxy for pharyngeal size, enabling the comparison of constriction across different people with different neck length and pharynx size. In healthy swallowing, constriction is expected to be complete, with larger measures reflecting incomplete or poor constriction. We report median values and 97.5% confidence intervals for pharyngeal constriction by consistency.

Outcome measures

Measure	Thin Liquid Barium n=76 Participants Participants were asked to take a series of 3 comfortably sized sips of thin liquid barium (Bracco E-Z-Paque powder) prepared in a 20% w/v concentration with water, and to swallow each sip when ready (without a cue).	Slightly Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized sips of slightly thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to swallow when ready (without a cue).	Mildly Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized sips of mildly thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to swallow when ready (without a cue).	Moderately Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized boluses of moderately thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to self-administer a comfortable bolus using a teaspoon and swallow when ready (without a cue).	Extremely Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized boluses of extremely thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to self-administer a comfortable bolus using a teaspoon and swallow when ready (without a cue).
Degree of Pharyngeal Constriction	1 % squared C2-C4 cervical spine length Interval 0.0 to 6.2	1.2 % squared C2-C4 cervical spine length Interval 0.0 to 5.0	1.2 % squared C2-C4 cervical spine length Interval 0.0 to 7.5	0.7 % squared C2-C4 cervical spine length Interval 0.0 to 4.9	0.2 % squared C2-C4 cervical spine length Interval 0.0 to 3.8

PRIMARY outcome

Timeframe: Baseline (single timepoint only)

Population: A sample of 80 adults was enrolled. Due to data quality issues, data for thin liquid were missing for 4 participants, and for 3 participants on the remaining consistencies.

During swallowing, the upper esophageal sphincter opens to allow the bolus to move from the pharynx into the esophagus. Narrow opening of the sphincter may obstruct bolus flow. We measured the degree (diameter) of upper esophageal sphincter opening on the frame of maximum distension. Line measurements were made in Image J software. This line measure was then divided by the length of the C2-C4 cervical spine. This cervical spine scalar provides a common anatomical reference that is a proxy for pharyngeal size, enabling the comparison of constriction across different people with different neck length and pharynx size. We report median values and 97.5% confidence intervals for pharyngeal constriction by consistency (thin, slightly thick, mildly thick, moderately thick and extremely thick liquid).

Outcome measures

Measure	Thin Liquid Barium n=76 Participants Participants were asked to take a series of 3 comfortably sized sips of thin liquid barium (Bracco E-Z-Paque powder) prepared in a 20% w/v concentration with water, and to swallow each sip when ready (without a cue).	Slightly Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized sips of slightly thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to swallow when ready (without a cue).	Mildly Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized sips of mildly thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to swallow when ready (without a cue).	Moderately Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized boluses of moderately thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to self-administer a comfortable bolus using a teaspoon and swallow when ready (without a cue).	Extremely Thick Liquid Barium n=77 Participants Participants were asked to take a series of 3 comfortably sized boluses of extremely thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to self-administer a comfortable bolus using a teaspoon and swallow when ready (without a cue).
Diameter of Upper Esophageal Sphincter Opening	21 % of the C2-C4 Cervical Spine Scalar Interval 9.0 to 32.0	19 % of the C2-C4 Cervical Spine Scalar Interval 9.0 to 31.0	19 % of the C2-C4 Cervical Spine Scalar Interval 9.0 to 30.0	15 % of the C2-C4 Cervical Spine Scalar Interval 8.0 to 26.0	16 % of the C2-C4 Cervical Spine Scalar Interval 9.0 to 26.0

PRIMARY outcome

Timeframe: Single timepoint (baseline only)

Population: A sample of 80 adults was enrolled. Due to data quality issues, data were missing for 2 participants.

The area of the pharynx was measured, in pixels (using ImageJ software), on a lateral view videofluoroscopic image showing the pharynx at rest. The resulting area measure was then divided by the squared length of the C2-C4 cervical spine. This cervical spine scalar provides a common anatomical reference that is a proxy for pharyngeal size, enabling the comparison of pharyngeal size across different people with different neck length. Larger pharyngeal area measures may reflect atrophy of the pharyngeal muscles while smaller pharyngeal area may reflect narrowing due to edema.We report median values and 97.5% confidence intervals for pharyngeal area.

Outcome measures

Measure	Thin Liquid Barium n=78 Participants Participants were asked to take a series of 3 comfortably sized sips of thin liquid barium (Bracco E-Z-Paque powder) prepared in a 20% w/v concentration with water, and to swallow each sip when ready (without a cue).	Slightly Thick Liquid Barium Participants were asked to take a series of 3 comfortably sized sips of slightly thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to swallow when ready (without a cue).	Mildly Thick Liquid Barium Participants were asked to take a series of 3 comfortably sized sips of mildly thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to swallow when ready (without a cue).	Moderately Thick Liquid Barium Participants were asked to take a series of 3 comfortably sized boluses of moderately thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to self-administer a comfortable bolus using a teaspoon and swallow when ready (without a cue).	Extremely Thick Liquid Barium Participants were asked to take a series of 3 comfortably sized boluses of extremely thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to self-administer a comfortable bolus using a teaspoon and swallow when ready (without a cue).
Pharyngeal Area at Rest	59 % of the squared C2-C4 length scalar Interval 37.0 to 92.0	—	—	—	—

SECONDARY outcome

Timeframe: Baseline (single timepoint only)

Population: A sample of 80 adults was enrolled. This parameter was only collected and analyzed in 40 of those participants, aged 21-59. Due to data quality issues, data were missing for 2 participants.

During swallowing, the tongue rises to contact the hard palate, generating pressure that squeezes the bolus backwards through the mouth towards the pharynx. The amplitude of tongue-palate pressure were measured continuously throughout swallowing using the KayPentax Digital Swallow Workstation Swallowing Signals Lab 3-bulb tongue pressure array, and the highest (peak) pressure was identified for each swallow. We will report mean values and standard error for peak pressure by bolus consistency (thin, slightly thick, mildly thick and moderately thick liquid). Higher amplitudes of pressure represent greater force for bolus propulsion.

Outcome measures

Measure	Thin Liquid Barium n=38 Participants Participants were asked to take a series of 3 comfortably sized sips of thin liquid barium (Bracco E-Z-Paque powder) prepared in a 20% w/v concentration with water, and to swallow each sip when ready (without a cue).	Slightly Thick Liquid Barium n=38 Participants Participants were asked to take a series of 3 comfortably sized sips of slightly thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to swallow when ready (without a cue).	Mildly Thick Liquid Barium n=38 Participants Participants were asked to take a series of 3 comfortably sized sips of mildly thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to swallow when ready (without a cue).	Moderately Thick Liquid Barium n=38 Participants Participants were asked to take a series of 3 comfortably sized boluses of moderately thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to self-administer a comfortable bolus using a teaspoon and swallow when ready (without a cue).	Extremely Thick Liquid Barium Participants were asked to take a series of 3 comfortably sized boluses of extremely thick barium, prepared in 20% w/v concentration using Bracco E-Z-Paque barium powder, bottled water, and Nestle Resource ThickenUp Clear xanthan gum thickener. Participants were instructed to self-administer a comfortable bolus using a teaspoon and swallow when ready (without a cue).
Amplitude of Tongue-Palate Pressure	16.53 mmHg Standard Error 2.21	25.51 mmHg Standard Error 3.58	28.61 mmHg Standard Error 3.47	51.89 mmHg Standard Error 8.83	—

Adverse Events

Healthy Adults

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

Serious adverse events

Adverse event data not reported

Other adverse events

Adverse event data not reported

Additional Information

Director, Swallowing Rehabilitation Research Laboratory

University Health Network

Phone: 416 597 3422

Email: tri-swallowinglab@uhn.ca

Results disclosure agreements

• Principal investigator is a sponsor employee
• Publication restrictions are in place