Commercial thickeners are frequently used to modify the consistency of liquids as a way of making drinking easier for people with dysphagia. The authors of this paper examine five thickening agents testing four different levels of viscosity, ranging from IDDSI level 1–4. The International Dysphagia Diet Standardisation Initiative (IDDSI) is a system of classifying ‘thickness’ of a fluid. The aim of this study was to explore how bolus flow, oropharyngeal and hyolaryngeal kinematics and rheological properties of the bolus itself changed with different types of thickeners on the market. Thirty healthy people without dysphagia were asked to drink 10 mL of fluid thickened using five commercial thickeners, each from IDDSI level 1–4, whilst undergoing videofluoroscopy. Various metrics related to the aims were assessed during fluoroscopy, including transit times of the bolus at various key points in swallowing biomechanics as well as laryngeal closure duration, often linked to airway protection. The main conclusions highlighted by the authors are: gum-based thickeners were more stable as they maintained the bolus cohesion and had longer laryngeal closure duration; starch-based thickeners had reduced cohesiveness and therefore greater variability in flow behaviour; and IDDSI levels 3 and 4 seemed to maintain the bolus in a higher oropharyngeal position, altering laryngeal closure dynamics, which the authors interpreted as safer swallowing in this cohort of healthy participants. They acknowledge that barium in itself alters fluid flow properties and that further research should also look at non-barium preparations as well as different dysphagic cohorts. It is useful to reflect on these findings which highlight the variation observed in normal healthy individuals without dysphagia and to consider the clinical implications when using commercial thickeners in dysphagic populations.
Through thick and thin, the type of thickener matters!
Reviewed by Roganie Govender
Flow Characteristics of Barium Thickened Liquids during Swallowing in Healthy Adults.
CONTRIBUTOR
Roganie Govender
University College London, Head & Neck Academic Centre, UK.
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