Spectral arc length as a method to quantify pharyngeal high-resolution manometric curve smoothness.

BACKGROUND: Pharyngeal high-resolution manometry (HRM) has emerged over the last decade as a valuable assessment tool for oropharyngeal dysphagia. Data analysis thus far has focused primarily on measures of pressure and duration within key anatomic regions. We apply spectral arc length (SPARC), a dimensionless metric for quantifying smoothness felt to indirectly reflect neuromuscular coordination, as a new method of describing manometric curves. We then use it to distinguish swallows from healthy subjects and those with dysphagia related to stroke. METHODS: Previously collected pharyngeal HRM data from eight subjects with history of stroke and eight age- and sex-matched controls were reviewed. Receiver operating characteristic (ROC) analysis was used to optimize SPARC inputs. SPARC was then computed for the velopharynx, tongue base, hypopharynx, and upper esophageal sphincter (UES), and the values were compared between the two subject groups. RESULTS: Optimized parameter settings yielded an ROC curve with area under the curve (AUC) of 0.953. Mean SPARC values differed between control and stroke subjects for the velopharynx (t = 3.25, p = 0.0058), tongue base (t = 4.77, p = 0.0003), and hypopharynx (t = 2.87, p = 0.0124). Values were similar for the UES (t = 0.43, p = 0.671). CONCLUSIONS: In this preliminary study, SPARC analysis was applied to distinguish control from post-stroke subjects. Considering alternative methods of analyzing pharyngeal HRM data may provide additional insight into the pathophysiology of dysphagia beyond what can be gleaned from measures of pressure and duration alone.

Pressure abnormalities in patients with Zenker's diverticulum using pharyngeal high-resolution manometry.

OBJECTIVES: Zenker's diverticulum is associated with reduced cricopharyngeal compliance and abnormal intrabolus pressure. However, it is unclear how the pharynx compensates for these deficits. Developments in manometric technology have improved our ability to capture pharyngeal pressure events. This study aims to describe the pharyngeal-upper esophageal sphincter (UES) pressure profile during swallowing in patients with Zenker's diverticulum. METHODS: High-resolution manometry was performed on 11 patients with symptomatic Zenker's diverticulum and 11 age- and sex-matched healthy controls during 10 mL liquid swallowing tasks. Pharyngeal and UES pressure magnitudes, durations, and integrals were compared between patients and controls using independent t tests. Other manometric parameters, including residual UES pressure at the time of maximum tongue base pressure and pharyngeal-UES pressure gradient, were also evaluated. A case example using three-dimensional high-resolution manometry is presented. RESULTS: Compared with healthy controls, patients with Zenker's diverticulum exhibited pressure abnormalities in the UES region. While baseline and pre-opening maximum pressures were not different, residual pressures were elevated (P = .001). Pharyngeal-UES pressure gradients did not differ between the two groups. CONCLUSION: This study used high-resolution manometry to characterize pharyngeal pressure dynamics in patients with Zenker's diverticulum. The changes occurring at the cricopharyngeus appear to result in persistent UES pressurization during UES opening, rather than high tonic resting pressure. Pharyngeal-UES pressure gradients, critical to bolus passage, were also preserved in this patient population. LEVEL OF EVIDENCE: 3b.

Effect of Body Position on Pharyngeal Swallowing Pressures Using High-Resolution Manometry.

The effect of body position and gravitational pull on the complex pressure-driven process of pharyngeal swallowing remains unknown. Using high-resolution manometry (HRM), this study aims to identify positional adaptations of pharyngeal physiology by evaluating swallowing pressure patterns in a series of inverted body positions. Ten healthy adults each underwent swallowing tasks with pharyngeal HRM at six body positions using an inversion table (0°[upright], 45°, 90°[supine], 110°, 135°, and 180°[fully inverted]). Repeated measures ANOVA was used to assess impact of position on pressure parameters, and pharyngeal-UES pressure gradients translate. Velopharyngeal pressures varied by position (P < 0.001), with significantly higher pressures generated with inversion ≥90°, compared with upright and 45°. Change in position did not significantly affect common mesopharyngeal pressures or swallowing pressure durations. UES valving mechanisms were preserved during inversion, with subtle variations observed in integral pressures (P = 0.011). Pharyngeal-UES pressure gradients changed with position (P < 0.01), increasing with inversion > 90° compared to upright and 45°. Mechanisms of deglutition may differ with position and relative direction of gravity, particularly when at > 45° inclination. Increased palatal pressure is generated in the upside-down position to achieve nasopharyngeal closure and prevent regurgitation. While other classically measured pressures may not consistently differ with positioning, many individuals exhibit adaptations in pressure gradients when inverted, likely due to a combination of changes in pharyngeal driving force and UES opening mechanisms. Identification of these changes, relative to position, further builds on our understanding of the adaptability of the pharyngeal swallowing system.

Methods for measuring swallowing pressure variability using high-resolution manometry.

Any movement performed repeatedly will be executed with inter-trial variability. Oropharyngeal swallowing is a complex sensorimotor action, and swallow-to-swallow variability can have consequences that impact swallowing safety. Our aim was to determine an appropriate method to measure swallowing pressure waveform variability. An ideal variability metric must be sensitive to known deviations in waveform amplitude, duration, and overall shape, without being biased by waveforms that have both positive and sub-atmospheric pressure profiles. Through systematic analysis of model waveforms, we found a coefficient of variability (CV) parameter on waveforms adjusted such that the overall mean was 0 to be best suited for swallowing pressure variability analysis. We then investigated pharyngeal swallowing pressure variability using high-resolution manometry data from healthy individuals to assess impacts of waveform alignment, pharyngeal region, and number of swallows investigated. The alignment that resulted in the lowest overall swallowing pressure variability was when the superior-most sensor in the upper esophageal sphincter reached half its maximum pressure. Pressures in the tongue base region of the pharynx were least variable and pressures in the hypopharynx region were most variable. Sets of 3 - 10 consecutive swallows had no overall difference in variability, but sets of 2 swallows resulted in significantly less variability than the other dataset sizes. This study identified variability in swallowing pressure waveform shape throughout the pharynx in healthy adults; we discuss implications for swallowing motor control.

Integrating the microbiota of the respiratory tract with the unified airway model.

The unified airway model has developed from indications that the upper and lower respiratory tracts share key elements of pathogenesis. These shared traits likely extend to similar niche characteristics that support bacterial communities, and as such, we suspect that similar microbes exist on upper and lower respiratory tract epithelium. Over the past decade and a half there have been significant improvements in microbiological identification and analysis due to the development of new molecular technologies, including next-generation sequencing. In this review, we provide an overview of the modern collection and sequencing methods involved in respiratory microbiota research, and outline the specific microbial communities that have been found to be associated with the healthy and diseased human respiratory tract. Demonstration of a remarkable similarity between the upper and lower respiratory tract in terms of microbiological presence adds further corroboration to the existence of a unified airway.

Pharyngeal swallowing pressures in the base-of-tongue and hypopharynx regions identified with three-dimensional manometry.

OBJECTIVES: This study aims to use three-dimensional (3D) high-resolution manometry to identify circumferential pressure patterns generated within the asymmetrical base-of-tongue and hypopharynx regions of the pharynx during deglutition. STUDY DESIGN: Case series. METHODS: Radial pressures in the regions of interest were evaluated during swallowing events in 12 healthy subjects using 3D high-resolution manometry. RESULTS: Repeated measures analysis of variance revealed asymmetrical pharyngeal clearance pressures in the base-of-tongue and hypopharynx regions during swallowing. A significant main effect of direction on pressure was found at the time point of average maximum pressure (P < 0.001) and for pressure integral (P < 0.001), with pressure primarily generated from the posterior direction. An interaction was noted between direction and location when comparing maximum directional pressures, regardless of time (P =0.045), highlighting the differences in anterior pressure production between regions. In contrast to the high posterior pressures produced in the base-of-tongue region, an anteroposterior dominant pressure pattern was observed in the hypopharynx. Pressure waveform complexity in the hypopharynx also is likely attributed to activity in the anterior and posterior directions. Symmetrical pressure generation was observed during intrabolus flow within the hypopharynx. CONCLUSION: This study shows that pressure is asymmetrically generated in the base-of-tongue and hypopharynx regions during swallowing of a 10-mL bolus, reflecting the complex anatomy within the pharynx. Understanding of these complex pressure patterns aids in the interpretation of high-resolution manometry and can help guide further study in the clinical assessment and treatment of pharyngeal pathology. LEVEL OF EVIDENCE: 4. Laryngoscope, 127:1989-1995, 2017.

Expiratory muscle strength training evaluated with simultaneous high-resolution manometry and electromyography.

OBJECTIVE: To examine feasibility of a simultaneous high-resolution pharyngeal manometry (HRM) and electromyography (EMG) experimental paradigm to detect swallowing-related patterns of palatal, laryngeal, and pharyngeal muscle activity during expiratory training. STUDY DESIGN: Technical report. METHODS: Simultaneous HRM, surface submental, and intramuscular EMG were acquired in two healthy participants during five tasks: 10-cc water swallow, maximum expiratory pressure (MEP) testing, and expiratory muscle strength training (EMST) at three pressure levels (sham, 50%, and 75% MEP). RESULTS: Experimental conditions were feasible. Velopharyngeal closing pressure, palate EMG activity, and pharyngeal EMG activity increased as expiratory load increased. In contrast, thyroarytenoid EMG activity was low during the expiratory task, consistent with glottic opening during exhalation. Submental EMG patterns were more variable during expiratory tasks. Intraluminal air pressures recorded with HRM were correlated with measured expiratory pressures and target valve-opening pressures of the EMST device. CONCLUSION: Results suggest that a simultaneous HRM/EMG/EMST paradigm may be used to detect previously unquantified swallowing-related muscle activity during EMST, particularly in the palate and pharynx. Our approach and initial findings will be helpful to guide future hypothesis-driven studies and may enable investigators to evaluate other muscle groups active during these tasks. Defining mechanisms of action is a critical next step toward refining therapeutic algorithms using EMST and other targeted treatments for populations with dysphagia and airway disorders. LEVEL OF EVIDENCE: 4. Laryngoscope, 127:797-804, 2017.