Dysphagia is estimated to affect ~8% of the world’s population (~590 million people). Texture-modified foods and thickened drinks are commonly used to reduce the risks of choking and aspiration. The International Dysphagia Diet Standardisation Initiative (IDDSI) was founded with the goal of developing globally standardized terminology and definitions for texture-modified foods and liquids applicable to individuals with dysphagia of all ages, in all care settings, and all cultures. A multi-professional volunteer committee developed a dysphagia diet framework through systematic review and stakeholder consultation. First, a survey of existing national terminologies and current practice was conducted, receiving 2050 responses from 33 countries. Respondents included individuals with dysphagia; their caregivers; organizations supporting individuals with dysphagia; healthcare professionals; food service providers; researchers; and industry. The results revealed common use of 3–4 levels of food texture (54 different names) and ≥3 levels of liquid thickness (27 different names). Substantial support was expressed for international standardization. Next, a systematic review regarding the impact of food texture and liquid consistency on swallowing was completed. A meeting was then convened to review data from previous phases, and develop a draft framework. A further international stakeholder survey sought feedback to guide framework refinement; 3190 responses were received from 57 countries. The IDDSI Framework (released in November, 2015) involves a continuum of 8 levels (0–7) identified by numbers, text labels, color codes, definitions, and measurement methods. The IDDSI Framework is recommended for implementation throughout the world.

https://link.springer.com/content/pdf/10.1007%2Fs00455-016-9758-y.pdf

Development of international terminology and definitions for texture-modified foods and thickened fluids used in dysphagia management: the IDDSI framework

Texture modification has become one of the most common forms of intervention for dysphagia, and is widely considered important for promoting safe and efficient swallowing. However, to date, there is no single convention with respect to the terminology used to describe levels of liquid thickening or food texture modification for clinical use. As a first step toward building a common taxonomy, a systematic review was undertaken to identify empirical evidence describing the impact of liquid consistency and food texture on swallowing behavior. A multi-engine search yielded 10,147 non-duplicate articles, which were screened for relevance. A team of ten international researchers collaborated to conduct full-text reviews for 488 of these articles, which met the study inclusion criteria. Of these, 36 articles were found to contain specific information comparing oral processing or swallowing behaviors for at least two liquid consistencies or food textures. Qualitative synthesis revealed two key trends with respect to the impact of thickening liquids on swallowing: thicker liquids reduce the risk of penetration–aspiration, but also increase the risk of post-swallow residue in the pharynx. The literature was insufficient to support the delineation of specific viscosity boundaries or other quantifiable material properties related to these clinical outcomes. With respect to food texture, the literature pointed to properties of hardness, cohesiveness, and slipperiness as being relevant both for physiological behaviors and bolus flow patterns. The literature suggests a need to classify food and fluid behavior in the context of the physiological processes involved in oral transport and flow initiation.

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The Influence of Food Texture and Liquid Consistency Modification on Swallowing Physiology and Function: A Systematic Review

It is clinically important to evaluate tongue function in terms of rehabilitation of swallowing and eating ability. We have developed a disposable tongue pressure measurement device designed for clinical use. In this study we used this device to determine standard values of maximum tongue pressure in adult Japanese. Eight hundred fifty-three subjects (408 male, 445 female; 20-79 years) were selected for this study. All participants had no history of dysphagia and maintained occlusal contact in the premolar and molar regions with their own teeth. A balloon-type disposable oral probe was used to measure tongue pressure by asking subjects to compress it onto the palate for 7 s with maximum voluntary effort. Values were recorded three times for each subject, and the mean values were defined as maximum tongue pressure. Although maximum tongue pressure was higher for males than for females in the 20-49-year age groups, there was no significant difference between males and females in the 50-79-year age groups. The maximum tongue pressure of the seventies age group was significantly lower than that of the twenties to fifties age groups. It may be concluded that maximum tongue pressures were reduced with primary aging. Males may become weaker with age at a faster rate than females; however, further decreases in strength were in parallel for male and female subjects.

Standard values of maximum tongue pressure taken using newly developed disposable tongue pressure measurement device.

Fluid thickening is a well-established management strategy for oropharyngeal dysphagia (OD). However, the effects of thickening agents on the physiology of impaired swallow responses are not fully understood, and there is no agreement on the degree of bolus thickening. To review the literature and to produce a white paper of the European Society for Swallowing Disorders (ESSD) describing the evidence in the literature on the effect that bolus modification has upon the physiology, efficacy and safety of swallowing in adults with OD. A systematic search was performed using the electronic Pubmed and Embase databases. Articles in English available up to July 2015 were considered. The inclusion criteria swallowing studies on adults over 18 years of age; healthy people or patients with oropharyngeal dysphagia; bolus modification; effects of bolus modification on swallow safety (penetration/aspiration) and efficacy; and/or physiology and original articles written in English. The exclusion criteria consisted of oesophageal dysphagia and conference abstracts or presentations. The quality of the selected papers and the level of research evidence were assessed by standard quality assessments. At the end of the selection process, 33 articles were considered. The quality of all included studies was assessed using systematic, reproducible, and quantitative tools (Kmet and NHMRC) concluding that all the selected articles reached a valid level of evidence. The literature search gathered data from various sources, ranging from double-blind randomised control trials to systematic reviews focused on changes occurring in swallowing physiology caused by thickened fluids. Main results suggest that increasing bolus viscosity (a) results in increased safety of swallowing, (b) also results in increased amounts of oral and/or pharyngeal residue which may result in post-swallow airway invasion, (c) impacts the physiology with increased lingual pressure patterns, no major changes in impaired airway protection mechanisms, and controversial effects on oral and pharyngeal transit time, hyoid displacements, onset of UOS opening and bolus velocity—with several articles suggesting the therapeutic effect of thickeners is also due to intrinsic bolus properties, (d) reduces palatability of thickened fluids and (e) correlates with increased risk of dehydration and decreased quality of life although the severity of dysphagia may be an confounding factor. The ESSD concludes that there is evidence for increasing viscosity to reduce the risk of airway invasion and that it is a valid management strategy for OD. However, new thickening agents should be developed to avoid the negative effects of increasing viscosity on residue, palatability, and treatment compliance. New randomised controlled trials should establish the optimal viscosity level for each phenotype of dysphagic patients and descriptors, terminology and viscosity measurements must be standardised. This white paper is the first step towards the development of a clinical guideline on bolus modification for patients with oropharyngeal dysphagia.

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Effect of Bolus Viscosity on the Safety and Efficacy of Swallowing and the Kinematics of the Swallow Response in Patients with Oropharyngeal Dysphagia: White Paper by the European Society for Swallowing Disorders (ESSD)

Maximum tongue strength was investigated and compared to mean swallowing pressure elicited by the anterior tongue to calculate the percentage of maximum tongue strength used during swallowing in 96 participants with normal swallowing, divided into three 20-year age groups. The purposes of this investigation were to investigate normal swallowing physiology and to determine whether tongue strength reserves diminished according to age or gender. The results of the study yielded significant maximum tongue strength differences between the youngest and oldest and middle and oldest age groups; the oldest group had the weakest tongues. Mean swallowing pressure did not differ based on age, but women were found to have significantly higher pressures than men. The percentage of maximum tongue strength used during swallowing did not vary as a function of age, but women used a significantly higher percentage of tongue strength to swallow than men. Based on the results, it appears that a diminishing strength reserve does not exist based on age, but it does exist based on gender. Specifically, it appears that women have a reduced tongue strength reserve compared to men. Clinical implications are discussed.

Differences in tongue strength across age and gender: is there a diminished strength reserve?

The availability of objective measures of tongue function presents a possible supplement to the clinical dysphagia evaluation. The purpose of this study was to improve our understanding of normal tongue physiology during swallowing and maximum isometric tasks, establish a preliminary database of tongue function variables, and determine if differences existed among the variables as a function of age, gender, or varied bolus consistency. Ninety subjects, divided into age and gender groups, participated in tasks that determined maximum isometric tongue pressure, mean tongue pressure during swallowing, and percentage of maximum isometric pressure used during swallowing. Descriptive statistics, correlations, and analyses of variance were computed to analyze the data. Results indicated that males had significantly higher maximum isometric pressures than females, and the youngest group had significantly higher maximum pressures than the oldest group. Mean swallowing pressures and percentage of maximum isometric pressures used during swallowing differed as a function of bolus type but did not differ as a function of age or gender. In addition, maximum isometric pressures were correlated with mean swallowing pressures, and mean swallowing pressures and percentage of maximum isometric pressures used during swallowing were correlated between consistencies.

Measures of Tongue Function Related to Normal Swallowing

Purpose This investigation sought to add to the extant literature on measures of normal tongue function, to provide information on measures of tongue function in a group of individuals with oral ph

Tongue measures in individuals with normal and impaired swallowing.

Cervical auscultation has been proposed as a technique to augment the clinical evaluation of dysphagia to improve its accuracy in the diagnosis of dysphagia. Before using cervical auscultation to reliably diagnose disordered swallowing, it is necessary to first acoustically characterize normal swallowing for comparison with dysphagic swallowing. Ninety-seven healthy adult participants consumed teaspoon boluses of various consistencies while the sounds of swallowing were recorded. Descriptive statistics were reported for measures of duration, intensity, and frequency of the acoustic swallowing signal. Correlations between the variables and between bolus consistencies were computed. Overall, results compared favorably with previous research. Significant correlations were found among several of the variables, including an increasing duration of the acoustic swallowing signal with increasing age and decreasing intensity of the signal with increasing age. None of the variables differed significantly as a function of gender. Of potential clinical relevance, significant correlations between bolus consistencies for the duration and intensity variables indicated relative similarities across bolus consistencies. Duration and intensity of the acoustic signal appeared to be the most reliable of the variables measured. These results could serve as a reference point for future studies into normal swallowing across multiple bolus consistencies and volumes and eventually be compared with disordered swallowing.

An Acoustic Profile of Normal Swallowing

Purpose Outcomes of script training for individuals with apraxia of speech (AOS) and mild anomic aphasia were investigated. Script training is a functional treatment that has been successful for in...

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Scott R. Youmans

Papers

Measures of Tongue Function Related to Normal Swallowing

Differences in tongue strength across age and gender: is there a diminished strength reserve?

Tongue measures in individuals with normal and impaired swallowing.

An Acoustic Profile of Normal Swallowing

Script Training Treatment for Adults With Apraxia of Speech