Development of a Non-invasive Device for Swallow Screening in Patients at Risk of Oropharyngeal Dysphagia: Results from a Prospective Exploratory Study

Cervical Auscultation for Detecting Oropharyngeal Aspiration in Paediatric and Adult Populations: A Systematic Review and Meta-Analysis

BACKGROUND

Cervical auscultation (CA) involves listening to swallowing and respiratory sounds and/or vibrations to detect oropharyngeal aspiration (OPA). CA has shown promising diagnostic test accuracy when used with the clinical swallowing examination and is gaining popularity in clinical practise. There has not been a review to date analysing the accuracy of CA in paediatric and adult populations with meta-analyses.

OBJECTIVES

To determine the accuracy of CA in detecting OPA in paediatric and adult populations, when compared to instrumental assessments.

SEARCH METHODS

Databases searched included MEDLINE, PubMed, Embase, CINAHL, AustHealth, Cochrane and Web of Science. The search was restricted between 01 October 2012 and 01 October 2022.

SELECTION CRITERIA

Inclusion criteria included (a) all clinical populations of all ages, (b) who have had an instrumental assessment and (c) CA. All study types were included.

DATA COLLECTION AND ANALYSIS

Studies were reviewed independently by two authors. The methodological quality of the studies was analysed using the QUADAS-2.

MAIN RESULTS

Ten studies met the inclusion criteria for this review and meta-analyses. The pooled diagnostic performance of CA in detecting OPA was 0.91 for sensitivity and 0.79 for specificity. The area under the curve summary receiver operating curve (sROC) was estimated to be 0.86, thereby indicating good discrimination of OPA. Most studies scored high for risk of bias in at least one domain in the QUADAS-2, likely attributed to a lack of high-quality prospectively designed studies.

CONCLUSIONS

There are promising diagnostic test accuracies for the use of CA in detection of OPA. Future research could include using CA in specific clinical populations and settings, and identifying standardised criteria for CA.

Videofluoroscopic Swallowing Studies: A Proposed Checklist

PURPOSE

The videofluoroscopic swallowing study (VFSS) is used widely in dysphagia research. However, variations exist in the conduct and interpretation of VFSS, including differences in contrast agents, food and fluid consistencies tested, patient positioning, intervention strategies trialed, fluoroscopy settings, resolution, and image storage solutions. It cannot be assumed that VFSS exams yield directly comparable results across different studies. It is essential that relevant elements of VFSS be clearly reported in research. The goal of this article is to outline optimal VFSS reporting as part of the Framework for RigOr aNd Transparency In REseaRch on Swallowing (FRONTIERS), a critical appraisal tool intended to promote rigor and transparency in dysphagia research.

METHOD

We developed a set of 27 questions regarding the rigor and transparency of VFSS reporting, based on review of previous research articles. These were reviewed by all members of the FRONTIERS Framework collaborative, to determine which questions were mandatory, unnecessary, or needed revision, prior to inclusion in the final critical appraisal tool.

RESULTS

The final FRONTIERS Framework tool contains 20 questions and seven subquestions regarding VFSS. These are grouped into four themes: patient/participant positioning, equipment and recording settings, contrast agents, and rating methods, including operational definitions and reliability.

CONCLUSIONS

The VFSS section of the FRONTIERS Framework tool is intended to facilitate and promote rigorous and transparent reporting of all elements that may influence the interpretation of VFSS in research. This critical appraisal tool can also be used to guide research design and the evaluation of study outcomes contributing to best practices in the field of dysphagia research.

Reliability and Confidence of Dynamic Imaging Grade of Swallowing Toxicity (DIGEST) Rating Among Research and Clinical Speech Pathologists Before and After Implementation of a Training Manual: A Multi-site Study

DIGEST is a validated, open-source method to grade the severity of pharyngeal dysphagia from the modified barium swallow (MBS) study. Dissemination and implementation of DIGEST is rising, making it critical to understand reliability and facilitators of accurate implementation among users. The aim was to assess reliability of the tool among speech-language pathology (SLP) raters practicing at multiple sites before and after review of a DIGEST training manual and evaluate confidence of DIGEST use pre-and post-training. Thirty-two SLPs from 5 sites participated in a blinded longitudinal DIGEST rating study. Raters were provided a standardized training set of MBS (n = 19). Initial SLP ratings (round 1, R1) were followed by a 2-4 week break before raters rated a re-keyed MBS set (round 2, R2). A minimum 4-8 week wash-out period then preceded self-study of the DIGEST training manual which was followed by a final rating (round 3, R3) and a post-manual survey afterwards. Baseline reliability (R1) of overall DIGEST was on average k = 0.70, reflecting agreement in the substantial range. Seventy-five percent of raters (24/32) demonstrated reliability ≥ 0.61 in the substantial to almost perfect range prior to training. Inter-rater reliability significantly improved from R1 to R3 after review of the DIGEST manual, with the largest change in DIGEST-Efficiency (mean change: DIGEST k = .04, p = .009, DIGEST-Safety k = .07, p = 0.03, and DIGEST-Efficiency k = .14, p = 0.009). Although DIGEST reliability at baseline was adequate in the majority of raters, self-study of the DIGEST training manual significantly improved inter-rater reliability and rater confidence using the DIGEST method, particularly when assigning DIGEST-Efficiency grade. These early data show promise that provider training may be useful to aid in fidelity of DIGEST implementation among SLP clinical users with varying DIGEST experience.

Bulbar function in spinal muscular atrophy (SMA): State of art and new challenges. 21st July 2023, Rome, Italy

Progressive bulbar involvement is frequent in spinal muscular atrophy, with prevalence and severity of deficits associated with type. The report provides an overview of the presentations made at the workshop grouped into 4 sessions: the first section was dedicated to videofluoroscopy with a revision of the existing protocols and discussion on which one should be used in routine clinical practice and in research settings. The second session was dedicated to interprofessional routine assessments of bulbar function, with a review of the recent clinical tools specifically developed for SMA. The third section was focused on the assessments performed by speech and language therapists/pathologists in the new SMA phenotypes. The last section focused on how the new therapies have changed the approach in rehabilitation for bulbar dysfunction. Finally, we present the consensus that was achieved on these aspects and possible action points from these.

Validation of the IDDSI funnel for liquid flow testing

In 2017, the International Dysphagia Diet Standardisation Initiative (IDDSI) introduced the IDDSI flow test which enables patients, clinicians, caregivers, food service professionals and researchers to classify liquid thickness into five levels based on the volume of liquid remaining in a standard 10 mL slip tip syringe after 10 s of flow under gravity. Within a few months of publishing the IDDSI flow test instructions, several barriers emerged: (1) the preferred model of syringe (BD 303134) was not equally accessible around the world, causing some users to perform flow tests with alternate models of syringe; (2) differences in syringe geometry across models led to variations in IDDSI flow test results; and (3) the need to use a second syringe for sample loading added complexity and cost to end users. To address these barriers, IDDSI designed the IDDSI funnel, a novel device, which combines the geometry of the BD 303134 syringe with a kitchen funnel to facilitate easy loading of liquid samples without need for a second syringe. In this report, we compare the IDDSI flow test results across two devices: syringe BD 303134 and IDDSI funnel. IDDSI level classifications were in complete agreement with the syringe reference test results in 67/73 (92%) of the test fluids and temperature conditions with mean difference of residual liquid across devices of 0.2 (2% full scale). These results demonstrate excellent correspondence between the two devices.

The effect of liquid consistency on penetration-aspiration: a Bayesian analysis of two large datasets

Introduction

Thickened liquids are commonly recommended to reduce the risk of penetration-aspiration. However, questions persist regarding the impact of bolus consistency on swallowing safety. The common practice of summarizing Penetration-Aspiration Scale (PAS) scores based on worst scores is a bias in prior analyses. The aim of this study was to examine the impact of liquid consistency on PAS scores using a Bayesian multilevel ordinal regression model approach, considering all scores across repeated bolus trials. A second aim was to determine whether PAS scores differed across thickener type within consistency.

Methods

We analyzed two prior datasets (D1; D2). D1 involved 678 adults with suspected dysphagia (289 female; mean age 69 years, range 20-100). D2 involved 177 adults (94 female; mean age 54 years, range 21-85), of whom 106 were nominally healthy and 71 had suspected dysphagia. All participants underwent videofluoroscopy involving ≥3 boluses of 20% w/v thin liquid barium and of xanthan-gum thickened barium in mildly, moderately and extremely thick consistencies. D2 participants also swallowed trials of slightly thick liquid barium, and starch-thickened stimuli for each thickened consistency. Duplicate blinded rating yielded PAS scores per bolus, with discrepancies resolved by consensus. PAS ratings for a total of 8,185 and 3,407 boluses were available from D1 and D2, respectively. Bayesian models examined PAS patterns across consistencies. We defined meaningful differences as non-overlapping 95% credible intervals (CIs).

Results

Across D1 and D2, penetration occurred on 10.87% of trials compared to sensate (0.68%) and silent aspiration (1.54%), with higher rates of penetration (13.47%) and aspiration (3.07%) on thin liquids. For D1, the probability of a PAS score > 2 was higher for thin liquids with weighted PAS scores of 1.57 (CI: 1.48, 1.66) versus mildly (1.26; CI: 1.2, 1.33), moderately (1.1; CI: 1.07, 1.13), and extremely thick liquids (1.04; CI: 1.02, 1.08). D2 results were similar. Weighted PAS scores did not meaningfully differ between thin and slightly thick liquids, or between starch and xanthan gum thickened liquids.

Discussion

These results confirm that the probability of penetration-aspiration is greatest on thin liquids compared to thick liquids, with significant reductions in PAS severity emerging with mildly thick liquids.

Development and Pilot Study of a Pediatric Screening for Feeding and Swallowing Disorders in Infants and Children: The Pediatric Screening–Priority Evaluation Dysphagia (PS–PED)

Feeding and swallowing disorders (FSD) are common during childhood, with a prevalence of 85% in children with neurodevelopmental disorders. A comprehensive screening is essential to identify FSD and improve health outcomes in a clinical setting. This study aims to develop a new Pediatric Screening tool capable of identifying FSD. This screening tool was developed in three steps: selecting variables based on clinical experience, searching the literature and finding agreement between experts with a two-round Delphi study. This process, which reached 97% of agreement between experts, led to the development of the Pediatric Screening–Priority Evaluation Dysphagia (PS–PED). PS–PED comprises 14 items divided into three main domains: clinical history, health status and feeding condition. We also carried out a pilot test for measuring internal consistency, as measured with Cronbach Coefficient alpha. Concurrent validity, as measured with Pearson correlation coefficient, was tested using a videofluoroscopy swallow study (VFSS) classified with the Penetration Aspiration Scale (PAS). The pilot test was conducted on 59 children with different health conditions. Our findings showed good internal consistency (alpha = 0.731), and a strong linear correlation with PAS (Pearson 0.824). Furthermore, comparing PS–PED and PAS scores, we find preliminary strong discriminant validity to identify children with FSD (p < 0.01). Our results provide evidence on using the 14-item PS–PED as a screening tool for FSD in a clinical sample of children with heterogeneous disease.

Research on a real-time dynamic monitoring method for silent aspiration after stroke based on semisupervised deep learning: A protocol study

Objective

This study aims to establish a real-time dynamic monitoring system for silent aspiration (SA) to provide evidence for the early diagnosis of and precise intervention for SA after stroke.

Methods

Multisource signals, including sound, nasal airflow, electromyographic, pressure and acceleration signals, will be obtained by multisource sensors during swallowing events. The extracted signals will be labeled according to videofluoroscopic swallowing studies (VFSSs) and input into a special dataset. Then, a real-time dynamic monitoring model for SA will be built and trained based on semisupervised deep learning. Model optimization will be performed based on the mapping relationship between multisource signals and insula-centered cerebral cortex-brainstem functional connectivity through resting-state functional magnetic resonance imaging. Finally, a real-time dynamic monitoring system for SA will be established, of which the sensitivity and specificity will be improved by clinical application.

Results

Multisource signals will be stably extracted by multisource sensors. Data from a total of 3200 swallows will be obtained from patients with SA, including 1200 labeled swallows from the nonaspiration category from VFSSs and 2000 unlabeled swallows. A significant difference in the multisource signals is expected to be found between the SA and nonaspiration groups. The features of labeled and pseudolabeled multisource signals will be extracted through semisupervised deep learning to establish a dynamic monitoring model for SA. Moreover, strong correlations are expected to be found between the Granger causality analysis (GCA) value (from the left middle frontal gyrus to the right anterior insula) and the laryngeal rise time (LRT). Finally, a dynamic monitoring system will be established based on the former model, by which SA can be identified precisely.

Conclusion

The study will establish a real-time dynamic monitoring system for SA with high sensitivity, specificity, accuracy and F1 score.

Swallow Detection with Acoustics and Accelerometric-Based Wearable Technology: A Scoping Review

Swallowing disorders, especially dysphagia, might lead to malnutrition and dehydration and could potentially lead to fatal aspiration. Benchmark swallowing assessments, such as videofluoroscopy or endoscopy, are expensive and invasive. Wearable technologies using acoustics and accelerometric sensors could offer opportunities for accessible and home-based long-term assessment. Identifying valid swallow events is the first step before enabling the technology for clinical applications. The objective of this review is to summarize the evidence of using acoustics-based and accelerometric-based wearable technology for swallow detection, in addition to their configurations, modeling, and assessment protocols. Two authors independently searched electronic databases, including PubMed, Web of Science, and CINAHL. Eleven (n = 11) articles were eligible for review. In addition to swallowing events, non-swallowing events were also recognized by dry (saliva) swallowing, reading, yawning, etc., while some attempted to classify the types of swallowed foods. Only about half of the studies reported that the device attained an accuracy level of >90%, while a few studies reported poor performance with an accuracy of <60%. The reviewed articles were at high risk of bias because of the small sample size and imbalanced class size problem. There was high heterogeneity in assessment protocol that calls for standardization for swallowing, dry-swallowing and non-swallowing tasks. There is a need to improve the current wearable technology and the credibility of relevant research for accurate swallowing detection before translating into clinical screening for dysphagia and other swallowing disorders.

AI-Based Detection of Aspiration for Video-Endoscopy with Visual Aids in Meaningful Frames to Interpret the Model Outcome

Disorders of swallowing often lead to pneumonia when material enters the airways (aspiration). Flexible Endoscopic Evaluation of Swallowing (FEES) plays a key role in the diagnostics of aspiration but is prone to human errors. An AI-based tool could facilitate this process. Recent non-endoscopic/non-radiologic attempts to detect aspiration using machine-learning approaches have led to unsatisfying accuracy and show black-box characteristics. Hence, for clinical users it is difficult to trust in these model decisions. Our aim is to introduce an explainable artificial intelligence (XAI) approach to detect aspiration in FEES. Our approach is to teach the AI about the relevant anatomical structures, such as the vocal cords and the glottis, based on 92 annotated FEES videos. Simultaneously, it is trained to detect boluses that pass the glottis and become aspirated. During testing, the AI successfully recognized the glottis and the vocal cords but could not yet achieve satisfying aspiration detection quality. While detection performance must be optimized, our architecture results in a final model that explains its assessment by locating meaningful frames with relevant aspiration events and by highlighting suspected boluses. In contrast to comparable AI tools, our framework is verifiable and interpretable and, therefore, accountable for clinical users.

Food-Grade Activated Charcoal for Contrast-Enhanced Photoacoustic Imaging of Aspiration: A Phantom Study

Aspiration pneumonia has the highest attributable mortality of all medical complications post-stroke, or in individuals with progressive neurological diseases. For optimum health outcomes for individuals with dysphagia, a non-invasive and convenient method for objectively detecting aspiration is needed. This study introduces a potential new aspiration screening method based on photoacoustic imaging (PAI), a medical imaging technology that measures the optical contrast of tissue rather than mechanical or elastic properties. In this preliminary study, a tissue-mimicking neck phantom was designed to test the performance of PAI for aspiration screening with a charcoal solution as a contrast agent. A 1064 nm wavelength light source was illuminated on the anterior of the neck phantom to induce the photoacoustic effect. The resulting photoacoustic signal of the charcoal contrast in the mock trachea was detected by a linear transducer array with a 2.25 MHz central ultrasound frequency. The phantom results showed that charcoal solution at 10 mg/ml exhibited strong photoacoustic signals when flowing into the phantom trachea. By overlaying the photoacoustic signals of the charcoal contrast on top of the ultrasound image, we were able to simultaneously visualize the movement of food contrast and a cross-section of tissue structures during mock swallowing. Moreover, we confirmed the ability to detect the flow of charcoal contrast at a small bolus volume of ~ 7 μl through the phantom, suggesting high sensitivity to detect small aspiration events. The study suggests that PAI holds promise to be developed as an aspiration detection tool with charcoal powder as a contrast agent.

Soft skin-interfaced mechano-acoustic sensors for real-time monitoring and patient feedback on respiratory and swallowing biomechanics

Swallowing is a complex neuromuscular activity regulated by the autonomic nervous system. Millions of adults suffer from dysphagia (impaired or difficulty swallowing), including patients with neurological disorders, head and neck cancer, gastrointestinal diseases, and respiratory disorders. Therapeutic treatments for dysphagia include interventions by speech-language pathologists designed to improve the physiology of the swallowing mechanism by training patients to initiate swallows with sufficient frequency and during the expiratory phase of the breathing cycle. These therapeutic treatments require bulky, expensive equipment to synchronously record swallows and respirations, confined to use in clinical settings. This paper introduces a wireless, wearable technology that enables continuous, mechanoacoustic tracking of respiratory activities and swallows through movements and vibratory processes monitored at the skin surface. Validation studies in healthy adults (n = 67) and patients with dysphagia (n = 4) establish measurement equivalency to existing clinical standard equipment. Additional studies using a differential mode of operation reveal similar performance even during routine daily activities and vigorous exercise. A graphical user interface with real-time data analytics and a separate, optional wireless module support both visual and haptic forms of feedback to facilitate the treatment of patients with dysphagia.

Which Videofluoroscopy Parameters Are Susceptible to the Influence of Differences in Barium Product and Concentration?

PURPOSE

Prior studies suggest there may be differences in videofluoroscopic measures of swallowing across different barium concentrations. Whether different barium products of identical concentration result in similar swallowing physiology remains unknown. This is important, as barium intended for videofluoroscopy (i.e., Bracco Varibar) is not available globally. Our aim was to identify differences in healthy swallowing across five different barium stimuli.

METHOD

Twenty healthy adults (10 women), aged 22-54 years, underwent videofluoroscopy including comfortable sips of thin liquid barium: two sips of 20% weight-to-volume (w/v) barium prepared with E-Z-HD powder, and two sips each of 20%w/v and 40%w/v barium prepared with Liquid Polibar Plus and E-Z-Paque powder. Recordings were analyzed according to the Analysis of Swallowing Physiology: Events, Kinematics and Timing Method. Measures of timing, kinematics and residue were obtained. Chi-square, Friedman's, and Wilcoxon signed-ranks test were used to identify differences across stimuli.

RESULTS

Significant differences were seen across barium stimuli for upper esophageal sphincter (UES) opening duration, UES diameter, pharyngeal area at maximum constriction, and residue. In all cases, smaller values were seen with the 20%w/v E-Z-HD stimulus; however, this stimulus had questionable opacity for visualization. Patterns of residue severity were not explained by barium concentration.

CONCLUSIONS

This study confirms that some measures of swallowing are influenced by barium product and/or concentration. Measures are not necessarily similar across different barium products at the same concentration. This study illustrates the importance of using standard and appropriate stimuli in videofluoroscopy, and for clinicians to report not only the product but also the concentration of stimuli used.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.20669712.

Screening Tools Designed to Assess and Evaluate Oropharyngeal Dysphagia in Adult Patients: A Scoping Review

Oropharyngeal Dysphagia (OD) significantly decreases a patient’s quality of life and poses a high economic burden to institutions. In this sense, evaluation and assessment are important interventions for health professionals, although current tools and instruments are multiple and are dispersed in the literature. The aim of this review was to map existing screening tools to assess and evaluate OD in adult patients, identify their relevant clinical parameters and respective contexts of use and provide a systematic approach and summary to better inform practice. A scoping review was developed guided by the JBI methodology and using PRISMA-ScR to report results published between 2014 and 2021, in English, Spanish and Portuguese. Databases included Medline, Academic Search Complete, CINAHL Complete, Scielo, Google Scholar, ScienceDirect, OpenGrey and B-On. Mendeley was used to store and screen data. A total of 33 studies were included in the study, of which 19 tools were identified, some being intervention-based tools and others an algorithm for decision. The most common context used was in the general population and older adults. Regarding clinical parameters, the most common were food consistency, presence of the cough reflex, swallowing effort, voice changes and weight. As oropharyngeal dysphagia concerns important risks for the patient, a rigorous assessment must be performed. In this sense, the review identified specific disease-related tools and more general instruments, and it is an important contribution to more efficient dysphagia screening and prevention.

Determining the Relationship Between Hyoid Bone Kinematics and Airway Protection in Swallowing

PURPOSE

Research remains equivocal regarding the links between hyoid movement and penetration-aspiration. The aims of this study were (a) to explore associations between hyoid parameters, laryngeal vestibule closure (LVC) parameters, and penetration-aspiration on thin liquids; and (b) to determine which of these parameters are the strongest predictors of penetration-aspiration.

METHOD

This study involved retrospective analysis of an existing videofluoroscopy data set, collected in 305 participants (152 males) with noncongenital/nonsurgical/non-oncological risk for dysphagia. We extracted data for six thin liquid swallows per participant, and obtained measures of hyoid movement (peak position, speed) and LVC (complete/incomplete, timing, duration). Resulting values were coded as typical/atypical relative to healthy reference data. Relationships were explored using chi-square tests and odds ratios (a) for the entire data set and (b) for the subset of data with complete LVC. Hierarchical logistic regression models determined the strongest predictors of penetration-aspiration.

RESULTS

Significant associations were found between penetration-aspiration and incomplete LVC, prolonged time-to-most-complete-LVC, short LVC duration, reduced anterior hyoid peak position, and reduced hyoid speed. Hyoid measures were also significantly associated with LVC parameters. In the first regression model, incomplete LVC and prolonged time-to-most-complete-LVC were the only significant predictors of penetration-aspiration. For cases with complete LVC, the only significant predictor was prolonged time-to-most-complete-LVC.

CONCLUSIONS

Although reduced anterior hyoid peak position and speed are associated with penetration-aspiration on thin liquids, these measures do not independently account for penetration-aspiration when considered in conjunction with measures of LVC. When identifying mechanisms explaining penetration-aspiration, clinicians should focus on LVC (complete/incomplete) and timeliness of LVC.

Effectiveness of Interventions for Dysphagia in Parkinson Disease: A Systematic Review

PURPOSE

Dysphagia is a common sequela of Parkinson disease (PD) and is associated with malnutrition, aspiration pneumonia, and mortality. This review article synthesized evidence regarding the effectiveness of interventions for dysphagia in PD.

METHOD

Electronic searches were conducted in Ovid MEDLINE, Embase, Cochrane Central Register of Controlled Trials, CINAHL, and speechBITE. Of the 2,015 articles identified, 26 met eligibility criteria: interventional or observational studies with at least five or more participants evaluating dysphagia interventions in adults with PD-related dysphagia, with outcomes measured using videofluoroscopic swallowing study (VFSS), fiberoptic endoscopic evaluation of swallowing (FEES), or electromyography (EMG). Risk of bias (RoB) was evaluated using the Evidence Project tool and predetermined criteria regarding the rigor of swallowing outcome measures.

RESULTS

Interventions were classified as follows: pharmacological (n = 11), neurostimulation (n = 8), and behavioral (n = 7). Primary outcome measures varied across studies, including swallowing timing, safety, and efficiency, and were measured using VFSS (n = 17), FEES (n = 6), and EMG (n = 4). Critical appraisal of study findings for RoB, methodological rigor, and transparency showed the majority of studies failed to adequately describe contrast media used, signal acquisition settings, and rater blinding to time point. Low certainty evidence generally suggested improved swallow timing with exercises with biofeedback and deep brain stimulation (DBS), improved safety with DBS and expiratory muscle strength training, and improved efficiency with the Lee Silverman Voice Treatment and levodopa.

CONCLUSIONS

Studies with lower RoB and greater experimental rigor showed potential benefit in improving swallowing efficiency but not safety. Further research investigating discrete changes in swallowing pathophysiology post-intervention is warranted to guide dysphagia management in PD.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.17132162.

Refining measurement of swallowing safety in the Dynamic Imaging Grade of Swallowing Toxicity (DIGEST) criteria: Validation of DIGEST version 2

BACKGROUND

Dynamic Imaging Grade of Swallowing Toxicity (DIGEST) is a validated method to grade the severity of pharyngeal swallowing impairment as a toxicity of cancer based on the degree and patterns of penetration/aspiration and pharyngeal residue over a standardly acquired radiographic modified barium swallow (MBS) study. Since its implementation in 2016, areas for the refinement of grading mild safety impairments have been identified by clinical and research users. The objective of this study was to assess the performance and validity of refined DIGEST_safety grading criteria (per DIGEST version 2 [DIGEST_v2 ]).

METHODS

Refined safety criteria were developed and vetted with clinical and research users. DIGEST_v2 included 2 changes to the safety criteria. All MBSs with blinded DIGEST version 1 grading were sampled from a registry database (1331 patients underwent MBS over the period of December 2005 to July 2019). New criteria were applied to derive DIGEST_safety grading version 2. Measures of criterion validity, including the MD Anderson Dysphagia Inventory [MDADI] composite score, the Modified Barium Swallow Impairment Profile (MBSImP) pharyngeal total, the MBSImP hyolaryngeal components (items 8-11), and the Performance Status Scale for Head and Neck Cancer Patients [PSS-HN] diet, were correlated with DIGEST_safety and overall DIGEST grades from versions 1 and 2 and were compared pairwise between reassigned grades.

RESULTS

With the application of version 2 safety criteria, 112 of 1331 examinations (8.4%) and 79 of 1331 examinations (5.9%) changed in their DIGEST_safety and overall grades, respectively. The safety and overall DIGEST grades (versions 1 and 2) significantly correlated with criterion measures, including the MBSImP pharyngeal total, laryngeal MBSImP parameters of interest, MDADI, and PSS-HN (P < .0001); correlations maintained a similar magnitude between versions 1 and 2. Forty-six upgraded examinations (reassigned from safety grade 1 per version 1 to grade 2 per version 2) performed similarly to other safety grade 2 examinations (version 1), and this was likewise true for 66 downgraded examinations (reassigned from safety grade 1 per version 1 to grade 0 per version 2).

CONCLUSIONS

Refined criteria defining mild safety impairments with the DIGEST methodology changed grades in small numbers of examinations. DIGEST_v2 criteria maintained criterion validity, demonstrated ordinality, and improved the performance of the method in these rare scenarios.

LAY SUMMARY

Dynamic Imaging Grade of Swallowing Toxicity (DIGEST) is a method developed and validated by the investigators in 2016 to grade the severity of pharyngeal swallowing dysfunction (dysphagia) with a decision tree or flowsheet to guide the clinician's review of a standard radiographic modified barium swallow study. This work reports on the validity of updated DIGEST criteria (version 2) that incorporate 2 modifications to the decision tree.

A Preliminary Investigation of Similarities of High Resolution Cervical Auscultation Signals Between Thin Liquid Barium and Water Swallows

Dysphagia, commonly referred to as abnormal swallowing, affects millions of people annually. If not diagnosed expeditiously, dysphagia can lead to more severe complications, such as pneumonia, nutritional deficiency, and dehydration. Bedside screening is the first step of dysphagia characterization and is usually based on pass/fail tests in which a nurse observes the patient performing water swallows to look for dysphagia overt signs such as coughing. Though quick and convenient, bedside screening only provides low-level judgment of impairment, lacks standardization, and suffers from subjectivity. Recently, high resolution cervical auscultation (HRCA) has been investigated as a less expensive and non-invasive method to diagnose dysphagia. It has shown strong preliminary evidence of its effectiveness in penetration-aspiration detection as well as multiple swallow kinematics. HRCA signals have traditionally been collected and investigated in conjunction with videofluoroscopy exams which are performed using barium boluses including thin liquid. An HRCA-based bedside screening is highly desirable to expedite the initial dysphagia diagnosis and overcome all the drawbacks of the current pass/fail screening tests. However, all research conducted for using HRCA in dysphagia is based on thin liquid barium boluses and thus not guaranteed to provide valid results for water boluses used in bedside screening. If HRCA signals show no significant differences between water and thin liquid barium boluses, then the same algorithms developed on thin liquid barium boluses used in diagnostic imaging studies, it can be then directly used with water boluses. This study investigates the similarities and differences between HRCA signals from thin liquid barium swallows compared to those signals from water swallows. Multiple features from the time, frequency, time-frequency, and information-theoretic domain were extracted from each type of swallow and a group of linear mixed models was tested to determine the significance of differences. Machine learning classifiers were fit to the data as well to determine if the swallowed material (thin liquid barium or water) can be correctly predicted from an unlabeled set of HRCA signals. The results demonstrated that there is no systematic difference between the HRCA signals of thin liquid barium swallows and water swallows. While no systematic difference was discovered, the evidence of complete conformity between HRCA signals of both materials was inconclusive. These results must be validated further to confirm conformity between the HRCA signals of thin liquid barium swallows and water swallows.

Telepractice and Dysphagia Management: The Era of COVID-19 and Beyond

The COVID-19 pandemic drove rapid and widespread uptake of telepractice across all aspects of healthcare. The delivery of dysphagia care was no exception, with telepractice recognized as a service modality that could support social distancing/infection control, overcome service delivery challenges created by lockdowns/service closures, and address consumer concerns about attending in-person appointments. Now, almost two years since most services first rapidly deployed telepractice, it is time to reflect on the big picture, and consider how telepractice will continue as a service option that is sustained and integrated into mainstream dysphagia care. It is also timely to consider the research agenda needed to support this goal. To this end, in this paper we present 4 discussion topics, which raise key considerations for the current and future use of telepractice within adult and pediatric dysphagia services. These are (1) Dysphagia services must meet consumer and service needs; (2) Aspects of dysphagia services can be safely and reliably provided via telepractice; (3) Telepractice can be used in flexible ways to support the delivery of dysphagia services; and (4) Providing quality dysphagia services via telepractice requires planned implementation and evaluation. Then directions for future research are discussed. These considerations are presented to help shift perspectives away from viewing telepractice as simply a COVID-19 "interim-care solution". Rather, we encourage clinicians, services, and researchers to embrace a future of "integrated care", where traditional dysphagia services are combined with telepractice models, to enhance the quality of care provided to our clients.

Advanced Machine Learning Tools to Monitor Biomarkers of Dysphagia: A Wearable Sensor Proof-of-Concept Study

Introduction

Difficulty swallowing (dysphagia) occurs frequently in patients with neurological disorders and can lead to aspiration, choking, and malnutrition. Dysphagia is typically diagnosed using costly, invasive imaging procedures or subjective, qualitative bedside examinations. Wearable sensors are a promising alternative to noninvasively and objectively measure physiological signals relevant to swallowing. An ongoing challenge with this approach is consolidating these complex signals into sensitive, clinically meaningful metrics of swallowing performance. To address this gap, we propose 2 novel, digital monitoring tools to evaluate swallows using wearable sensor data and machine learning.

Methods

Biometric swallowing and respiration signals from wearable, mechano-acoustic sensors were compared between patients with poststroke dysphagia and nondysphagic controls while swallowing foods and liquids of different consistencies, in accordance with the Mann Assessment of Swallowing Ability (MASA). Two machine learning approaches were developed to (1) classify the severity of impairment for each swallow, with model confidence ratings for transparent clinical decision support, and (2) compute a similarity measure of each swallow to nondysphagic performance. Task-specific models were trained using swallow kinematics and respiratory features from 505 swallows (321 from patients and 184 from controls).

Results

These models provide sensitive metrics to gauge impairment on a per-swallow basis. Both approaches demonstrate intrasubject swallow variability and patient-specific changes which were not captured by the MASA alone. Sensor measures encoding respiratory-swallow coordination were important features relating to dysphagia presence and severity. Puree swallows exhibited greater differences from controls than saliva swallows or liquid sips (p < 0.037).

Discussion

Developing interpretable tools is critical to optimize the clinical utility of novel, sensor-based measurement techniques. The proof-of-concept models proposed here provide concrete, communicable evidence to track dysphagia recovery over time. With refined training schemes and real-world validation, these tools can be deployed to automatically measure and monitor swallowing in the clinic and community for patients across the impairment spectrum.

Automatic annotation of cervical vertebrae in videofluoroscopy images via deep learning

Judging swallowing kinematic impairments via videofluoroscopy represents the gold standard for the detection and evaluation of swallowing disorders. However, the efficiency and accuracy of such a biomechanical kinematic analysis vary significantly among human judges affected mainly by their training and experience. Here, we showed that a novel machine learning algorithm can with high accuracy automatically detect key anatomical points needed for a routine swallowing assessment in real-time. We trained a novel two-stage convolutional neural network to localize and measure the vertebral bodies using 1518 swallowing videofluoroscopies from 265 patients. Our network model yielded high accuracy as the mean distance between predicted points and annotations was 4.20 ± 5.54 pixels. In comparison, human inter-rater error was 4.35 ± 3.12 pixels. Furthermore, 93% of predicted points were less than five pixels from annotated pixels when tested on an independent dataset from 70 subjects. Our model offers more choices for speech language pathologists in their routine clinical swallowing assessments as it provides an efficient and accurate method for anatomic landmark localization in real-time, a task previously accomplished using an off-line time-sinking procedure.

Determining the Impact of Thickened Liquids on Swallowing in Patients Undergoing Irradiation for Oropharynx Cancer

The current standard for the treatment of oropharynx cancers is radiation therapy. However, patients are frequently left with dysphagia characterized by penetration-aspiration (impaired safety) and residue (impaired efficiency). Although thickened liquids are commonly used to manage dysphagia, we lack evidence to guide the modification of liquids for clinical benefit in the head and neck cancer population. The objective of this study was to assess the impact of slightly and mildly thick liquids on penetration-aspiration and residue in 12 patients with oropharyngeal cancer who displayed penetration-aspiration on thin liquid within 3 to 6 months after completion of radiotherapy. Significantly fewer instances of penetration-aspiration were seen with slightly and mildly thick liquids as compared with thin (P < .05). No differences were found across stimuli in the frequency of residue. Patients with oropharyngeal cancers who present with post-radiation therapy dysphagia involving penetration-aspiration on thin liquids may benefit from slightly and mildly thick liquids without risk of worse residue.

Chest-Worn Inertial Sensors: A Survey of Applications and Methods

Inertial Measurement Units (IMUs) are frequently implemented in wearable devices. Thanks to advances in signal processing and machine learning, applications of IMUs are not limited to those explicitly addressing body movements such as Activity Recognition (AR). On the other hand, wearing IMUs on the chest offers a few advantages over other body positions. AR and posture analysis, cardiopulmonary parameters estimation, voice and swallowing activity detection and other measurements can be approached through chest-worn inertial sensors. This survey tries to introduce the applications that come with the chest-worn IMUs and summarizes the existing methods, current challenges and future directions associated with them. In this regard, this paper references a total number of 57 relevant studies from the last 10 years and categorizes them into seven application areas. We discuss the inertial sensors used as well as their placement on the body and their associated validation methods based on the application categories. Our investigations show meaningful correlations among the studies within the same application categories. Then, we investigate the data processing architectures of the studies from the hardware point of view, indicating a lack of effort on handling the main processing through on-body units. Finally, we propose combining the discussed applications in a single platform, finding robust ways for artifact cancellation, and planning optimized sensing/processing architectures for them, to be taken more seriously in future research.

The Risk of Penetration-Aspiration Related to Residue in the Pharynx

Purpose Reference data from healthy adults under the age of 60 years suggest that the 75th and 95th percentiles for pharyngeal residue on swallows of thin liquids are 1% and 3%(C2-4)2, respectively. We explored how pharyngeal residue below versus above these values prior to a swallow predicts penetration-aspiration. Method The study involved retrospective analysis of a previous research data set from 305 adults at risk for dysphagia. Participants swallowed six thin boluses and three each of mildly, moderately, and extremely thick barium in videofluoroscopy. Raters measured preswallow residue in %(C2-4)2 units and Penetration-Aspiration Scale (PAS) scores for each swallow. Swallows were classified as (a) "clean baseline" (with no preswallow residue), (b) "clearing" swallows of residue with no new material added, or (c) swallows of "additional material" plus preswallow residue. Frequencies of PAS scores of ≥ 3 were compared across swallow type by consistency according to residue severity (i.e., ≤ vs. > 1%(C2-4)2 and ≤ vs. > 3%(C2-4)2. Results The data set comprised 2,541 clean baseline, 209 clearing, and 1,722 swallows of additional material. On clean baseline swallows, frequencies of PAS scores of ≥ 3 were 5% for thin and mildly thick liquids and 1% for moderately/extremely thick liquids. Compared to clean baseline swallows, the odds of penetration-aspiration on thin liquids increased 4.60-fold above the 1% threshold and 4.20-fold above the 3% threshold (mildly thick: 2.11-fold > 1%(C2-4)2, 2.26-fold > 3%(C2-4)2). PAS scores of ≥ 3 did not occur with clearing swallows of moderately/extremely thick liquids. Lower frequencies of above-threshold preswallow residue were seen for swallows of additional material than for clearing swallows. Compared to clean baseline swallows, the odds of PAS scores of ≥ 3 on swallows of additional material increased ≥ 1.86-fold above the 1% threshold and ≥ 2.15-fold above the 3% threshold, depending on consistency. Conclusion The data suggest that a pharyngeal residue threshold of 1%(C2-4)2 is a meaningful cut-point for delineating increased risk of penetration-aspiration on a subsequent swallow.

Measurement of Pharyngeal Residue From Lateral View Videofluoroscopic Images

Purpose The field lacks consensus about preferred metrics for capturing pharyngeal residue on videofluoroscopy. We explored four different methods, namely, the visuoperceptual Eisenhuber scale and three pixel-based methods: (a) residue area divided by vallecular or pyriform sinus spatial housing ("%-Full"), (b) the Normalized Residue Ratio Scale, and (c) residue area divided by a cervical spine scalar (%(C2-4)2). Method This study involved retrospective analysis of an existing data set of videofluoroscopies performed in 305 adults referred on the basis of suspected dysphagia, who swallowed 15 boluses each (six thin and three each of mildly, moderately, and extremely thick 20% w/v barium). The rest frame at the end of the initial swallow of each bolus was identified. Duplicate measures of pharyngeal residue were made independently by trained raters; interrater reliability was calculated prior to discrepancy resolution. Frequency distributions and descriptive statistics were calculated for all measures. Kendall's τb tests explored associations between Eisenhuber scale scores and pixel-based measures, that is, %-Full and %(C2-4)2. Cross-tabulations compared Eisenhuber scale scores to 25% increments of the %-Full measure. Spearman rank correlations evaluated relationships between the %-Full and %(C2-4)2 measures. Results Complete data were available for 3,545 boluses: 37% displayed pharyngeal residue (thin, 36%; mildly thick, 41%; moderately thick, 35%; extremely thick, 34%). Eisenhuber scale scores showed modest positive associations with pixel-based measures but inaccurately estimated residue severity when compared to %-Full measures with errors in 20.6% of vallecular ratings and 14.2% of pyriform sinus ratings. Strong correlations (p < .001) were seen between the %-Full and %(C2-4)2 measures, but the %-Full measures showed inflation when spatial housing area was small. Conclusions Generally good correspondence was seen across different methods of measuring pharyngeal residue. Pixel-based measurement using an anatomical reference scalar, for example, (C2-4)2 is recommended for valid, reliable, and precise measurement.

Psychometric assessment and validation of the dysphagia severity rating scale in stroke patients

Post stroke dysphagia (PSD) is common and associated with poor outcome. The Dysphagia Severity Rating Scale (DSRS), which grades how severe dysphagia is based on fluid and diet modification and supervision requirements for feeding, is used for clinical research but has limited published validation information. Multiple approaches were taken to validate the DSRS, including concurrent- and predictive criterion validity, internal consistency, inter- and intra-rater reliability and sensitivity to change. This was done using data from four studies involving pharyngeal electrical stimulation in acute stroke patients with dysphagia, an individual patient data meta-analysis and unpublished studies (NCT03499574, NCT03700853). In addition, consensual- and content validity and the Minimal Clinically Important Difference (MCID) were assessed using anonymous surveys sent to UK-based Speech and Language Therapists (SLTs). Scores for consensual validity were mostly moderate (62.5-78%) to high or excellent (89-100%) for most scenarios. All but two assessments of content validity were excellent. In concurrent criterion validity assessments, DSRS was most closely associated with measures of radiological aspiration (penetration aspiration scale, Spearman rank rs = 0.49, p < 0.001) and swallowing (functional oral intake scale, FOIS, rs = -0.96, p < 0.001); weaker but statistically significant associations were seen with impairment, disability and dependency. A similar pattern of relationships was seen for predictive criterion validity. Internal consistency (Cronbach's alpha) was either "good" or "excellent". Intra and inter-rater reliability were largely "excellent" (intraclass correlation >0.90). DSRS was sensitive to positive change during recovery (medians: 7, 4 and 1 at baseline and 2 and 13 weeks respectively) and in response to an intervention, pharyngeal electrical stimulation, in a published meta-analysis. The MCID was 1.0 and DSRS and FOIS scores may be estimated from each other. The DSRS appears to be a valid tool for grading the severity of swallowing impairment in patients with post stroke dysphagia and is appropriate for use in clinical research and clinical service delivery.

Use of the Penetration-Aspiration Scale in Dysphagia Research: A Systematic Review

The penetration-aspiration scale (PAS) is an 8-point scale used to characterize the depth and response to airway invasion during videofluoroscopy. Though widely used in the field of deglutition, there is a lack of consensus regarding the statistical properties of the scale. In order to better understand the state of the literature and the statistical use of the PAS, a systematic review was undertaken to descriptively examine trends in statistical and reporting practices of the PAS since its inception. Online databases were searched for studies citing the original PAS article, which yielded 754 unique articles. Of these, 183 studies were included in the review. Results showed inconsistencies in the statistical use of the scale; 79 studies treated the PAS as ordinal, 71 as categorical, and 49 as interval. Ten types of categorizations were identified. Reporting of power analyses (9%), as well as inter- (26%) and intra-rater (17%) reliability, was uncommon. Among studies that administered multiple bolus volumes or consistencies, 55% reported PAS analyses at the participant/group level only. This review confirms the existence of discrepancies in the statistical treatment of the PAS. A lack of consensus among researchers limits comparisons between studies. The approach to handling this scale dictates the statistical tests used, potentially affecting results and interpretations. Consistent application of statistically sound approaches to PAS analyses is vital for the future of deglutition research.