Reference Values for Healthy Swallowing Across the Range From Thin to Extremely Thick Liquids

Area of Science:

• Physiology
• Biomechanics
• Deglutition studies

Background:

• Thickened liquids are common dysphagia interventions.
• Understanding liquid bolus transport and swallowing physiology is crucial.
• Gaps exist in knowledge regarding incremental liquid thickening effects.

Purpose of the Study:

• Establish reference values for bolus flow and swallowing physiology.
• Investigate healthy adults across a continuum of liquid consistencies.
• Quantify physiological responses to varying liquid thicknesses.

Main Methods:

• Videofluoroscopy in 38 healthy adults.
• Swallowing thin to extremely thick barium liquids (xanthan gum).
• ASPEKT method for analyzing swallowing events, kinematics, and timing.

Main Results:

• Thin liquids (10-14 ml) typically involved single swallows with complete physiological closure and minimal residue.
• Increased liquid thickness significantly reduced penetration odds.
• Longer hyoid burst interval and higher bolus position at swallow onset observed with thicker liquids.

Conclusions:

• New reference data for swallowing physiology across liquid consistencies.
• Thickened liquids may reduce aspiration/penetration risk in healthy adults.
• Swallowing physiology is largely preserved across a wide range of liquid thicknesses.