The practice of thickening liquids has become one of the most frequently used interventions for swallowing impairment (dysphagia). However, the terminology used to describe thickened liquids (such as nectar-thick and honey-thick) is subjective and we lack empirical evidence about how alterations in liquid consistency affect swallowing function and physiology. The International Dysphagia Diet Standardisation Initiative is a multidisciplinary task force ( that has recently developed a new taxonomy of terms to label different levels of liquid consistency used in dysphagia management; these are paired with operational definitions and practical gravity-flow measurement techniques that can be used by caregivers and clinicians to confirm the category of any liquid at the time of preparation or serving. The goal of the current proposal is to measure the in vitro physiological flow of liquids representative of the IDDSI levels of liquid consistency (thin, slightly-thick, milly-thick, moderately-thick and extremely-thick). Physiological measures of liquid flow require an understanding both of the rheological properties of the liquid (gravity-flow; viscosity) and the forces that are applied to the liquid during swallowing (tongue pressure; swallowing muscle contraction). Additional sensory attributes of the bolus (such as slipperiness, graininess and cohesiveness) are also likely to be relevant. We will measure these properties and study bolus flow in healthy adults to establish a reference perspective of expected flow in the context of healthy tongue pressure generation. We will then collect comparative measures in individuals with dysphagia of different etiologies (stroke, acquired brain injury, oropharyngeal cancer, post cervical spine surgery, and neurodegenerative disease) to determine how alterations in swallowing motor function impact liquid flow. These measurements will provide information to guide clinicians in determining optimal levels of thickening to recommend for patients with dysphagia. This research is highly significant because it will establish a new foundation of understanding with respect to the influence of thickened liquids on swallowing. This is essential for advancing clinical practice and setting the stage for future treatment efficacy research.

Public Health Relevance

Thickened liquids have become the most common intervention for dysphagia (swallowing impairment), yet we lack a clear understanding of how this intervention works to achieve clinical benefit. In this project, we will advance our understanding of how thickening influences swallowing by measuring the physiological flow of 5 incremental degrees of liquid thickening. These measures of physiological flow will take into consideration both the physical flow properties of these liquids and the forces applied during swallowing by healthy adults and individuals with swallowing impairment due to stroke, brain injury, oropharyngeal cancer, post cervical spine surgery and neurodegenerative disease.

National Institute of Health (NIH)
National Institute on Deafness and Other Communication Disorders (NIDCD)
Research Project (R01)
Project #
Application #
Study Section
Motor Function, Speech and Rehabilitation Study Section (MFSR)
Program Officer
Shekim, Lana O
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University Health Network
Zip Code
M5 2M9
Peladeau-Pigeon, Melanie; Steele, Catriona M (2017) Age-Related Variability in Tongue Pressure Patterns for Maximum Isometric and Saliva Swallowing Tasks. J Speech Lang Hear Res 60:3177-3184
Keller, Heather H; Carrier, Natalie; Slaughter, Susan E et al. (2017) Prevalence and Determinants of Poor Food Intake of Residents Living in Long-Term Care. J Am Med Dir Assoc 18:941-947
Namasivayam-MacDonald, Ashwini M; Burnett, Lynsey; Nagy, Ahmed et al. (2017) Effects of Tongue Strength Training on Mealtime Function in Long-Term Care. Am J Speech Lang Pathol 26:1213-1224
Steele, Catriona M (2017) The influence of tongue strength on oral viscosity discrimination acuity. J Texture Stud :
Steele, Catriona M; Grace-Martin, Karen (2017) Reflections on Clinical and Statistical Use of the Penetration-Aspiration Scale. Dysphagia :
Cichero, Julie A Y; Lam, Peter; Steele, Catriona M et al. (2017) Development of International Terminology and Definitions for Texture-Modified Foods and Thickened Fluids Used in Dysphagia Management: The IDDSI Framework. Dysphagia 32:293-314
Waito, Ashley A; Valenzano, Teresa J; Peladeau-Pigeon, Melanie et al. (2017) Trends in Research Literature Describing Dysphagia in Motor Neuron Diseases (MND): A Scoping Review. Dysphagia 32:734-747
Namasivayam-MacDonald, Ashwini M; Morrison, Jill M; Steele, Catriona M et al. (2017) How Swallow Pressures and Dysphagia Affect Malnutrition and Mealtime Outcomes in Long-Term Care. Dysphagia 32:785-796
Frazier, Jacqueline; Chestnut, Amanda H; Jackson, Arwen et al. (2016) Understanding the Viscosity of Liquids used in Infant Dysphagia Management. Dysphagia 31:672-9
Nagy, Ahmed; Peladeau-Pigeon, Melanie; Valenzano, Teresa Josephine et al. (2016) The effectiveness of the head-turn-plus-chin-down maneuver for eliminating vallecular residue. Codas 28:113-7

Showing the most recent 10 out of 37 publications