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

Abstract

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.

Detecting pharyngeal post-swallow residue by ultrasound examination: a case series.

“…geal residue [18]. Therefore, healthcare providers often modify the viscosity of the food and liquid to reduce pharyngeal post-swallow residue when the residue was detected.…”

Does a Water Protocol Improve the Hydration and Health Status of Individuals with Thin Liquid Aspiration Following Stroke? A Randomized Controlled Trial

“…There has been growing concern, however, about the blanket prescription of thickened liquids for a number of reasons: (i) not all who aspirate thin liquids will develop pneumonia and prescription of modified diets can be unnecessarily restrictive [9,10]; (ii) patients may not like drinking thickened liquids and are, therefore, frequently non-compliant [11][12][13]; (iii) there is a potential for increased aspiration risk of thickened liquids postswallow due to pharyngeal residue [14][15][16]; (iv) there is an increased risk of developing pneumonia or of dying if an individual aspirates thickened fluids or more solid substances as compared with thin fluids making the diagnostic process even more critical [17] and (v) there is limited empirical evidence of the medical effectiveness of fluid viscosity modification in terms of chest infection, nutritional status, hydration and mortality [14,18,19]. By far the greatest concern about thickened liquid prescription is that individuals with dysphagia do not consume enough fluids.…”

Quality of life in swallowing of the elderly patients affected by stroke

“…For a characterization about the consistencies, the questionnaire describes soft foods as those that are easier to chew, as for the most soft foods, they are processed in a blender or food processor. Steele et al observed that there is a convention with regard to the terminology used to describe thickening levels or texture of foods, not having a global rating (5,36) . The International Initiative of Diets in Dysphagia (IDDSI) has developed a new terminology standard and global definition consisting of a pyramid and identified eight levels to describe the modified food and liquid thickened texture used by individuals with dysphagia of all age groups, and in all cultures with regard to liquid: Extremely thin, moderately thick, midly thick, slightly thick and thin, about the food: regular, soft, minced e moist, pureed and liquidised.…”