Christina H. Smith

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

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.

Oral and Oropharyngeal Perceptions of Fluid Viscosity Across the Age Span

Research demonstrates that varying sensory input, including the characteristics of a bolus, changes swallow physiology. Altering the consistency of fluids is a common compensatory technique used in dysphagia management to facilitate change. However, it is not known what variations in viscosity can be perceived in the oral cavity or oropharynx or if age affects oral and oropharyngeal perceptions of fluid viscosity. This study aims to establish the ability of normal adults to perceive fluid viscosity in the oral cavity and oropharynx and to determine if, within this population, there are age-related changes in oral and oropharyngeal perceptions. Sensitivity was established by deriving the exponent for the psychophysical law for fluid viscosity in both the oral cavity and the oropharynx, using modulus-free magnitude estimation with Newtonian fluids of corn syrup and water. Sixty normal volunteers, aged 21–84 years, participated. Results indicate that the exponent for oral perception of fluid viscosity was 0.3298, while for oropharyngeal perception it was 0.3148. Viscosity perception deteriorates with increasing age. Men exhibited a more marked deterioration in sensitivity than women. This study contributes to the literature on oral and oropharyngeal perceptions and on aging. The results provide a basis for work with individuals with dysphagia.

Variation of the apparent viscosity of thickened drinks

BACKGROUND In dysphagia care, thickening powders are widely added to drinks to slow their flow speed by increasing their viscosity. Current practice relies on subjective evaluation of viscosity using verbal descriptors. Several brands of thickener are available, with differences in constituent ingredients and instructions for use. Some thickened fluids have previously been shown to exhibit time-varying non-Newtonian flow behaviour, which may complicate attempts at subjective viscosity judgement. AIMS The aims were to quantify the apparent viscosity over time produced by thickeners having a range of constituent ingredients, and to relate the results to clinical practice. METHODS & PROCEDURES A comparative evaluation of currently available thickener products, including two which have recently been reformulated, was performed. Their subjective compliance to the National Descriptors standards was assessed, and their apparent viscosity was measured using a rheometer at shear rates representative of situations from slow tipping in a beaker (0.1 s⁻¹) to a fast swallow (100 s⁻¹). Testing was performed repeatedly up to 3 h from mixing. OUTCOMES & RESULTS When mixed with water, it was found that most products compared well with subjective National Descriptors at three thickness levels. The fluids were all highly non-Newtonian; their apparent viscosity was strongly dependent on the rate of testing, typically decreasing by a factor of almost 100 as shear rate increased. All fluids showed some change in viscosity with time from mixing; this varied between products from -34% to 37% in the tests. This magnitude was less than the difference between thickness levels specified by the National Descriptors. CONCLUSIONS & IMPLICATIONS The apparent viscosity of thickened fluids depends strongly on the shear rate at which it is examined. This inherent behaviour is likely to hinder subjective evaluation of viscosity. If quantitative measures of viscosity are required (for example, for standardization purposes), they must therefore be qualified with information of the test conditions.

Factors Related to Dropout in a Study of Head and Neck Cancer Patients after Surgery

The extent and nature of dropout was assessed in a longitudinal study whose objective was to define and quantify the functional effects of oral surgical resection and reconstruction on speech and swallowing function in patients with head and neck cancer. Of 150 patients who were enrolled to be followed up with speech and swallow assessments for 1 year after surgery, 113 (75%) dropped out and 37 (25%) returned to complete the study at the final 12-month evaluation point. In general, those completing the study had a smaller resection than the patients who dropped out before the 12-month evaluation. Fifty percent of the dropout was accounted for by medical reasons, 23% by administrative reasons, and 27% by patient-specific reasons (ie, reasons known only to the patient). Analysis of the dropout categories revealed that higher cancer stage, larger volume of resection, and having a flap surgical closure versus a primary closure or skin graft increased a patients chance of dropping out. A larger volume of resection was also related to an increased chance of being a patient-specific dropout. Patients who reported no or low alcohol usage had a greater chance of completing follow-up than being a patient-specific dropout.

Thickened fluids: Investigation of users' experiences and perceptions

BACKGROUND & AIMS Fluid thickeners are an important and commonly-used strategy to manage swallowing difficulties however there are no reports of the perceptions and experiences of parents of children using thickeners. METHODS Semi-structured interviews of 14 parents having a child using fluid thickeners due to swallowing difficulties. RESULTS Parents reported improvements in quality of life and health through the use of thickeners. They also reported persistent difficulties in the use of thickeners. CONCLUSIONS Results showed unanimous goodwill and positive attitudes towards thickeners and their observed benefits, tempered by common difficulties with thickeners (variability and unpredictability). There remains scope for improvements of commercial thickeners and in information conveyed to users.

Swallowing interventions for the treatment of dysphagia after head and neck cancer: a systematic review of behavioural strategies used to promote patient adherence to swallowing exercises

BackgroundDysphagia is a significant side-effect following treatment for head and neck cancers, yet poor adherence to swallowing exercises is frequently reported in intervention studies. Behaviour change techniques (BCTs) can be used to improve adherence, but no review to date has described the techniques or indicated which may be more associated with improved swallowing outcomes.MethodsA systematic review was conducted to identify behavioural strategies in swallowing interventions, and to explore any relationships between these strategies and intervention effects. Randomised and quasi-randomised studies of head and neck cancer patients were included. Behavioural interventions to improve swallowing were eligible provided a valid measure of swallowing function was reported. A validated and comprehensive list of 93 discrete BCTs was used to code interventions. Analysis was conducted via a structured synthesis approach.ResultsFifteen studies (8 randomised) were included, and 20 different BCTs were each identified in at least one intervention. The BCTs identified in almost all interventions were: instruction on how to perform the behavior, setting behavioural goals and action planning. The BCTs that occurred more frequently in effective interventions, were: practical social support, behavioural practice, self-monitoring of behaviour and credible source for example a skilled clinician delivering the intervention. The presence of identical BCTs in comparator groups may diminish effects.ConclusionsSwallowing interventions feature multiple components that may potentially impact outcomes. This review maps the behavioural components of reported interventions and provides a method to consistently describe these components going forward. Future work may seek to test the most effective BCTs, to inform optimisation of swallowing interventions.

Identification of behaviour change components in swallowing interventions for head and neck cancer patients: protocol for a systematic review

BackgroundDysphagia (difficulty in swallowing) is a predictable consequence of head and neck cancer and its treatment. Loss of the ability to eat and drink normally has a devastating impact on quality of life for survivors of this type of cancer. Most rehabilitation programmes involve behavioural interventions that include swallowing exercises to help improve swallowing function. Such interventions are complex; consisting of multiple components that may influence outcomes. These interventions usually require patient adherence to recommended behaviour change advice. To date, reviews of this literature have explored whether variation in effectiveness can be attributed to the type of swallowing exercise, the use of devices to facilitate use of swallowing muscles, and the timing (before, during or after cancer treatment). This systematic review will use a behavioural science lens to examine the content of previous interventions in this field. It aims to identify (a) which behaviour change components are present, and (b) the frequency with which they occur in interventions deemed to be effective and non-effective.Methods/designClinical trials of behavioural interventions to improve swallowing outcomes in patients with head and neck cancers will be identified via a systematic and comprehensive search of relevant electronic health databases, trial registers, systematic review databases and Web of Science. To ascertain behaviour change intervention components, we will code the content for its theory basis, intervention functions and specific behaviour change techniques, using validated tools: the Theory Coding Scheme, Behaviour Change Wheel and Behaviour Change Technique Taxonomy v1. Study quality will be assessed for descriptive purposes only. Given the specialisation and focus of this review, a small yield of studies with heterogeneous outcome measures is anticipated. Therefore, narrative synthesis is considered more appropriate than meta-analysis. We will also compare the frequency of behavioural components in effective versus non-effective interventions, where effectiveness is indicated by statistically significant changes in swallowing outcomes.DiscussionThis review will provide a synthesis of the behaviour change components in studies that currently represent best evidence for behavioural swallowing interventions for head and neck cancer patients. Results will provide some guidance on the choice of optimal behavioural strategies for the development of future interventions.Systematic review registrationPROSPERO CRD42015017048

What do parents of children with dysphagia think about their MDT? A qualitative study

Objectives To seek the experiences and perspectives of parents caring for children with dysphagia, with emphasis on their experiences of working within their childs multidisciplinary team (MDT). Setting This research was completed in community settings, within families’ homes across the UK. Participants 14 families self-selected to participate in the study. Criteria specified that participants must care for a child under the age of 18 and to decrease ambiguity the term ‘diagnosis of dysphagia’ was defined as the need for modified (thickened) fluids. Exclusion criteria: caring for an adult over the age of 18; diet and fluid modifications for reasons other than dysphagia (eg, for symptomatic treatment of gastro-oesophageal reflux disease. Participants were interviewed within their homes using a semistructured questionnaire and data was analysed using a descriptive phenomenological approach through use of thematic coding and constant comparison. Themes and relationships were inductively generated from the data. Results Participants universally expressed a desire to be involved with their childs MDT; this study identified the following facilitators and barriers to collaboration: accessing services, professional knowledge and professional skillset. Participants described three means of responding to these barriers: reacting emotionally, seeking solutions and making decisions. Conclusions This study recorded in-depth reports of participants’ experiences of working with healthcare providers. Despite government-driven efforts towards person-centred healthcare and social care, participants shared accounts of times when this has not occurred, describing a negative impact on the well-being and quality of life of their child and family.

Modifying the consistency of food and fluids for swallowing difficulties in dementia

This is the protocol for a review and there is no abstract. The objectives are as follows: (1) To determine the effectiveness of modifying the consistency of food and fluids in improving oral intake and reducing laryngeal penetration and aspiration (2) To evaluate the adverse effects of modifying the consistency of food and fluids in adults with oropharyngeal dysphagia and dementia

Speech and swallowing rehabilitation following head and neck cancer: are we hearing the patient's voice? Our experience with ten patients.

Dear Editor, Swallowing and speech difficulties after treatment for advanced oral and oropharyngeal tumours are highly prevalent and often require a protracted period of rehabilitation. Changes in function continue to occur beyond 12 months post-treatment. The disruption of normal anatomy caused by surgical excision and/or fibrotic changes following chemoradiotherapy may result in some patients never regaining the ability to satisfactorily eat and drink by mouth despite therapy intervention. It is our experience that a proportion of patients may perceive their speech as unsatisfactory to continue with certain jobs which demand articulatory precision and voice projection. It is ultimately only patients themselves who determine the impact of their functional deficits and how satisfied they are with their rehabilitation. However, in clinical practice, therapy goals are often determined from the results of impairment-based tools such as instrumental swallowing assessments (videofluoroscopy and fibre-optic endoscopic evaluation of swallowing), articulation tests, clinician ratings and very occasionally patient questionnaires. Clinicians devise therapy or exercise programmes aimed at minimising the impairments identified. In our own practice, swallowing rehabilitation almost always takes priority over speech. Although patients’ views are acknowledged, a systematic and consistent method to incorporate this into setting goals for their rehabilitation will be useful. A few studies of the head and neck patient population have sought to compare clinician and patient views on function and quality of life issues. It is apparent from these studies that clinicians and patients may differ in their views and correspondingly may have a different focus for rehabilitation. An approach that incorporates patients’ priorities in the planning of rehabilitation goals is likely to more successfully meet patient expectations. In this report of a pilot study, we describe the use of validated swallowing and speech questionnaires to compile statements that were ranked by patients to reflect their priorities for swallowing and communication rehabilitation.