Physiological Flow of Liquids in Healthy Swallowing

Completed

• Conditions: Healthy Swallowing; Aging; Deglutition
• Interventions: Other: Starch-thickened liquids; Other: Xanthan-gum thickened liquids; Combination Product: Barium concentration

• Registration Number: NCT04114617
• Lead Sponsor: University Health Network, Toronto

Brief Summary

Thickened liquids are commonly used as an intervention for people with dysphagia (swallowing impairment). However, the field currently lacks a proper understanding of how this intervention works. The overall goal of the project is to collect measurements of bolus flow through the oropharynx (i.e., mouth and throat) during swallowing. The factors that are expected to influence bolus flow include the liquid/food consistency (i.e., thin, slightly-thick, mildly-thick, moderately-thick, extremely thick, solid) and the forces applied during swallowing (i.e., tongue pressures and swallowing muscle contraction). The objective is to determine how these factors interact to influence the flow of a bolus through the oropharynx in healthy swallowing.

Detailed Description

The aims of this study are as follows:

Aim 1: To determine the relationship between bolus flow and healthy swallowing physiology. The investigators will collect concurrent videofluoroscopic and physiological measures of swallowing (tongue pressure, electromyography \[sEMG\]) in healthy adults using barium stimuli across the continuum of liquid consistency (thin, slightly thick, mildly thick, moderately thick and extremely thick liquids, as defined by the International Dysphagia Diet Standardisation Initiative, www.iddsi.org). Significance: This will show the impact of consistency on bolus flow through the oropharynx, controlling for the forces used to initiate flow and propel the bolus.

Aim 2: To compare healthy swallowing physiology for barium versus non-barium stimuli. The investigators will collect physiological measures of swallowing using barium and non-barium stimuli matched for consistency. Significance: This will determine how swallowing behaviors (tongue pressures, sEMG) differ between barium and non-barium stimuli with matched consistency, enabling us to develop models of flow accounting for these differences.

Aim 3: To compare healthy swallowing physiology across different commercial barium products. Significance: This will determine whether differences in barium concentration or brand influence swallowing behaviors, enabling us to make recommendations regarding ideal contrast agents for use in radiographic swallowing assessment.

Study Timeline

• Study Start: 2016-01-01
• Primary Completion: 2019-09-12
• Study First Submitted: 2019-09-27
• Study First Submitted QC: 2019-10-01
• Study First Posted: 2019-10-03
• Study Completion: 2020-12-31
• Results First Submitted: 2022-05-19
• Status Verified: 2022-11
• Results First Submitted QC: 2022-11-22
• Last Update Submitted: 2022-11-22
• Results First Posted: 2022-12-21
• Last Update Posted: 2022-12-21

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 80

Inclusion Criteria

• healthy adults

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Exclusion Criteria

• prior history of swallowing, motor speech, gastro-esophageal or neurological difficulties, chronic sinusitis or taste disturbance
• history of surgery to the speech or swallowing apparatus (other than routine tonsillectomy or adenoidectomy)
• Type 1 Diabetes
• cognitive communication difficulties that may hinder comprehension of the study documents
• known allergies to latex, food coloring or dental glue
• current pregnancy
• recent x-ray to the neck (in the past 6 months)
• occupationally exposure to radiation exceeding 10 milliSieverts in the year

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Study & Design

• Study Type: OBSERVATIONAL
• Study Design: Not specified

Arm && Interventions

Group	Intervention	Description
Healthy Adults	Starch-thickened liquids	Participants will be asked to swallow a series of up to 54 liquid stimuli: a) liquid barium (different brands and concentrations); b) a 20% w/v concentration liquid barium thickened to different consistencies using either a starch-based or xanthan-gum based food thickener; and c) lemon-flavored water thickened to different consistencies using either a starch-based or xanthan-gum based food thickener.
Healthy Adults	Xanthan-gum thickened liquids	Participants will be asked to swallow a series of up to 54 liquid stimuli: a) liquid barium (different brands and concentrations); b) a 20% w/v concentration liquid barium thickened to different consistencies using either a starch-based or xanthan-gum based food thickener; and c) lemon-flavored water thickened to different consistencies using either a starch-based or xanthan-gum based food thickener.
Healthy Adults	Barium concentration	Participants will be asked to swallow a series of up to 54 liquid stimuli: a) liquid barium (different brands and concentrations); b) a 20% w/v concentration liquid barium thickened to different consistencies using either a starch-based or xanthan-gum based food thickener; and c) lemon-flavored water thickened to different consistencies using either a starch-based or xanthan-gum based food thickener.

Primary Outcome Measures

Name	Time	Method
Duration of Upper Esophageal Sphincter Opening	Baseline (single timepoint only)	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.
Laryngeal Vestibule Closure Duration	Baseline (single timepoint only)	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.
Diameter of Upper Esophageal Sphincter Opening	Baseline (single timepoint only)	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).
Duration of the Time Interval Between Onset of the Hyoid Burst and Opening of the Upper Esophageal Sphincter	Baseline (single timepoint only)	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.
Duration of the Time Interval Between Onset of the Pharyngeal Swallow and Closure of the Entrance to the Airway ("Time-to-Laryngeal-Vestibule-Closure")	Baseline (single timepoint only)	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.
Degree of Pharyngeal Constriction	Baseline (single timepoint only)	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.
Number of Participants Displaying More Than 2 Swallows Per Bolus	Baseline (single timepoint only)	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.
Duration of the Time Interval Between the Bolus Entering the Pharynx and Onset of the Pharyngeal Swallow ("Swallow Reaction Time")	Baseline (single timepoint only)	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.
Number of Participants With Unsafe Swallowing	Baseline (single timepoint only)	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.
Amount of Residue in the Pharynx	Baseline (single timepoint only)	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).
Pharyngeal Area at Rest	Single timepoint (baseline only)	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.

Secondary Outcome Measures

Name	Time	Method
Amplitude of Tongue-Palate Pressure	Baseline (single timepoint only)	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.

Trial Locations

Locations (1)

Toronto Rehabilitation Institute; 🇨🇦 Toronto, Ontario, Canada