Instrumental texture assessment of IDDSI texture levels for dysphagia management. Part 1: Thickened fluids.

Thickened fluids are commonly used in the medical management of individuals who suffer from swallowing difficulty (known as dysphagia). International Dysphagia Diet Standardization Initiative (IDDSI) developed a standardized terminology and description for texture-modified foods and thickened fluids to allow dysphagia patients to receive the correct consistency of food/drink. Syringe flow test and fork drip test are suggested by IDDSI to identify the drink category (IDDSI Levels 1-4). These practical methods are widely welcomed by carers and patients because of their simplicity. However, these methods are not most feasible for industrial applications, where objective measurements are required for industry for the purpose of quality control of such products. Therefore, our aim in this work was to develop quantitative and objective measurements that best describe IDDSI level category for use as an objective framework. Two measuring techniques, syringe flow test and fork drip test, recommended by IDDSI were evaluated in two different sets of experiment. Participants were recruited to categorize fluid samples of known texture parameters using syringe flow test and fork drip test techniques. The apparent stress measured from Ball-Back Extrusion (BBE) technique for each of the fluid category (IDDSI Levels 1-4) was calculated. Bands of apparent stress for each of the fluid category were developed from two measuring techniques, syringe flow test and fork drip test. An inconsistency was observed between these two measuring techniques for IDDSI Level 3 fluid due to different dominating factors in the two tests. However, we proposed to combine the results from the two experiments to develop a quantitative range for each IDDSI Level as objective complements to the IDDSI Framework. Thickened fluid manufacturers are encouraged to follow the proposed guidelines presented once they are clinically validated and use them fine-tune their products, thus enhancing the safety of individuals with dysphagia.

Instrumental texture assessment of IDDSI texture levels for dysphagia management. Part 2: Texture modified foods.

Texture-modified foods and thickened fluids play a major role in clinical treatment for individuals who suffer from swallowing difficulties (known as dysphagia). International Dysphagia Diet Standardization Initiative (IDDSI) developed a standardized terminology and description for texture-modified foods and thickened fluids to allow dysphagia patients to receive the correct consistency of food/drink. While the IDDSI framework provides a consistent texture description (Levels 0-7) and is widely accepted as an international standard, testing and assessment of IDDSI texture level are qualitative in nature and subjective in manner. These methods were proposed primarily for use by frontline carers, but are not most ideal for industrial purposes of quality control of such products. Therefore, the main aim of this work was to develop a quantitative instrumental method that best describes IDDSI levels as an objective framework. A set of test samples, including commercially available instant mashed potato, baby rice cereal, and cooked potato cubes of varying texture, were prepared. Two IDDSI measuring techniques, fork pressure test and spoon tilt test, were used to evaluate texture grades of these samples. Puncture and compression tests based on texture analyzer were used to assess cohesiveness, adhesiveness, firmness, and hardness for each food category (Levels 4-7). Thresholds of cohesiveness and adhesiveness, as well as bands of acceptable firmness and hardness for each food category were clearly identified and are proposed as objective complements to the IDDSI framework.

The Importance of Extensional Rheology in Bolus Control during Swallowing.

Thickened fluids are commonly used in the medical management of individuals who suffer swallowing difficulty (known as dysphagia). Previous studies have shown that the rheological properties of a liquid affect the flow behavior of the bolus in swallowing, such as pharyngeal transit time. While there is no doubt that shear rheology is a highly important factor for bolus flow, it is suspected that extensional properties of a liquid bolus also plays an important role in swallowing, due to elongation of the bolus as it flows through the oropharynx. Our aim in this work was to observe the effect of extensional viscosity on pharyngeal transit time and elongation of the bolus during swallowing. Eight samples of thickened liquid barium that were shear-controlled, but varied in extensional viscosity and two samples that were extensional-controlled, but varied in shear viscosity were swallowed by eight healthy individuals. Data were collected under lateral view of videofluoroscopy swallow study (VFSS); measures of pharyngeal transit time and the ratio of the length to the width of the bolus on the frame of Upper Esophageal Sphincter (UES) opening were taken from the VFSS recordings. It was observed that the pharyngeal transit time generally increases when the fluids are thickened to higher IDDSI consistency. Additionally, higher extensional viscosity fluids reduced the elongation of the bolus during swallowing, thus potentially reducing the risk of post-swallow residue due to bolus breakage. This study confirmed the relevance of the extensional viscosity of the bolus in swallowing.