Swallowing Mechanics Associated With Artificial Airways, Bolus Properties, and Penetration-Aspiration Status in Trauma Patients

Pilot Study of Quantitative Methods for Differentiating Pharyngeal Swallowing Mechanics by Dysphagia Etiology

Quantitative analysis of modified barium swallow (MBS) imaging is useful to determine the impact of various disease states on pharyngeal swallowing mechanics. In this retrospective proof of concept study, kinematic analysis and computational analysis of swallowing mechanics (CASM) were used to demonstrate how these methods differentiate swallowing dysfunction by dysphagia etiology. Ten subjects were randomly selected from four cohorts of dysphagic patients including COPD, head and neck cancer (HNC), motor neuron disease, and stroke. Each subject was age- and gender-matched with healthy, non-dysphagic controls. MBS videos of 5 ml thin and 5 ml thick bolus trials from each subject were used. A MATLAB tracker tool was adapted and updated to collect and compile data for each video (n = 160). For kinematic measurements, a MANOVA was performed with post-hoc analyses to determine group differences. For CASM measurements, a morphometric canonical variate analysis with post hoc analysis was performed to determine group differences. Kinematic analyses indicated statistically significant differences between HNC cohort and controls in distance measurements for hyolaryngeal approximation (p = .001), laryngeal elevation (p = 0.0001), pharyngeal shortening (p = 0.0002), and stage transition duration timing (p = 0.002). Timing differences were noted between the stroke cohort and controls for pharyngeal transit time (p = 0.007). Multivariate morphometric canonical variate analysis showed significant differences between etiology groups (p < 0.0001) with eigenvectors indicating differing patterns of swallowing mechanics. This study demonstrated that swallowing mechanics among cohorts of dysphagic patients can be differentiated using kinematics and CASM, providing different but complementary quantitative methods for investigating the impact of various disease states on swallowing function.

Predictors of swallowing outcomes in patients with combat-injury related dysphagia

BACKGROUND

Traumatic injuries, such as those from combat-related activities, can lead to complicated clinical presentations that may include dysphagia.

METHODS

This retrospective observational database study captured dysphagia-related information for 215 US military service members admitted to the first stateside military treatment facility after sustaining combat-related or combat-like traumatic injuries. A multidimensional relational database was developed to document the nature, course, and management for dysphagia in this unique population and to explore variables predictive of swallowing recovery using Bayesian statistical modeling and inferential statistical methods.

RESULTS

Bayesian statistical modeling revealed the importance of maxillofacial fractures and soft tissue loss as primary predictors of poor swallowing outcomes. The presence of traumatic brain injury (TBI), though common, did not further complicate dysphagia outcomes. A more detailed examination and rating of videofluoroscopic swallow studies from a subset of 161 participants supported greater impairment for participants with maxillofacial trauma and no apparent relationship between having sustained a TBI and swallow functioning.

CONCLUSION

These analyses revealed that maxillofacial trauma is a stronger indicator than TBI of dysphagia severity and slower or incomplete recovery following combat-related injuries.

LEVEL OF EVIDENCE

Therapeutic/Care Management study, level IV.

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.

Taste Manipulation and Swallowing Mechanics in Trauma-Related Sensory-Based Dysphagia

Purpose This study explored the effects of high-concentration taste manipulation trials on swallow function in persons with sensory-based dysphagia. Method Dysphagia researchers partnered with clinical providers to prospectively identify traumatically injured U.S. military service members (N = 18) with sensory-based dysphagia as evidenced by delayed initiation and/or decreased awareness of residue/penetration/aspiration. Under videofluoroscopy, participants swallowed trials of 3 custom-mixed taste stimuli: unflavored (40% weight/volume [wt/vol] barium sulfate in distilled water), sour (2.7% wt/vol citric acid in 40% wt/vol barium suspension), and sweet-sour (1.11% wt/vol citric acid plus 8% wt/vol sucrose in 40% wt/vol barium suspension). Trials were analyzed and compared via clinical rating tools (the Modified Barium Swallow Impairment Profile [Martin-Harris et al., 2008] and the Penetration-Aspiration Scale [Rosenbek, Robbins, Roecker, Coyle, & Wood, 1996]). Additionally, a computational analysis of swallowing mechanics (CASM) was applied to a subset of 9 swallows representing all 3 tastants from 3 participants. Results Friedman's tests for the 3 stimuli revealed significantly (p < .05) improved functional ratings for Penetration-Aspiration Scale and pharyngoesophageal opening. CASM indicated differences in pharyngeal swallowing mechanics across all tastant comparisons (p ≤ .0001). Eigenvectors revealed increased tongue base retraction, hyoid elevation, and pharyngeal shortening for sweet-sour and, to a lesser extent, sour than for unflavored boluses. Conclusion Advantageous changes in certain parameters of oropharyngeal swallowing physiology were noted with high-intensity tastants per both clinical ratings and subsequent CASM, suggesting potential therapeutic application for taste manipulation.

Functional Modules of Pharyngeal Swallowing Mechanics

OBJECTIVES

The present retrospective cohort study aims to test the hypothesis that elements of swallowing mechanics including hyoid movement, laryngeal elevation, tongue base retraction, pharyngeal shortening, pharyngeal constriction, and head and neck extension can be grouped into functional modules, and that these modules are predictably altered in disease states.

METHODS

Modified barium swallow video clips of a thick and a thin liquid swallow from 40 normal patients and 10 dysphagic post-treatment oropharyngeal head-and-neck cancer (HNC) patients were used in this study. Coordinate locations of 12 anatomical landmarks mapping pharyngeal swallowing mechanics were tracked on every frame during the pharyngeal phase of each swallow using a custom-made MATLAB tool. Morphometric modularity hypothesis testing was performed on these coordinate data to characterize the modular elements of swallowing function in each cohort using MorphoJ software.

RESULTS

The elements of normal swallowing can be grouped into four functional modules including bolus propulsion, pharyngeal shortening, airway protection, and head and neck posture. Modularity in HNC patient showed an intact airway protection module but altered bolus propulsion and pharyngeal shortening modules. To cross-validate the alteration in modules, a post hoc analysis was performed, which showed significantly increased vallecular (P < .04) and piriform (P < .05) residue but no significant change in aspiration status in the HNC cohort versus controls.

CONCLUSIONS

This study suggests that while pharyngeal swallowing mechanics is highly complex, the system is organized into functional modules, and that changes in modularity impacts swallowing performance. This approach to understanding swallowing function may help the patient care team better address swallowing difficulties.

LEVEL OF EVIDENCE

2b.