Characterization of pharyngeal contractile integral using pharyngeal manometry in children.

OBJECTIVES: Pharyngeal contractile integral (PhCI) is the product of mean pharyngeal contractile amplitude, length, and duration, and provides a single metric for the vigor of entire pharyngeal contraction. A major limitation in children is lack of characterization of PhCI on high-resolution pharyngeal manometry. We aimed to determine and compare the values of PhCI in children with the abnormal and normal videofluoroscopic study of swallow (VFSS). METHODS: Children who underwent high-resolution pharyngeal and esophageal manometry (HRPM/HREM), as well as VFSS, were divided into two groups; "normal VFSS" and "abnormal VFSS" groups. PhCI was calculated from the pharyngo-esophageal manometry analysis software (MMS, v9.5, Laborie Medical Technologies), and compared in these two groups. RESULTS: Of 67 children, 9 had abnormal VFSS (mean age 64 ± 50 months; 66.7% males), while 58 had normal VFSS (mean age 123 ± 55 months; 47% males). The mean PhCI in abnormal and normal VFSS groups was 82.00 ± 51.90 and 147.28 ± 53.89 mmHg.s.cm, respectively (p = 0.001). Subjects with abnormal VFSS were significantly younger than those with normal VFSS (p = 0.003). However, after adjusting for the VFSS result, age was no longer related to PhCI (p = 0.364). In subgroup analysis of children presenting with dysphagia, the mean PhCI in abnormal (9 subjects) and normal (36 subjects) VFSS groups was 82.00 ± 51.90 and 141.86 ± 50.39 mmHg.s.cm, respectively (p = 0.003). CONCLUSIONS: PhCI was significantly lower in children with abnormal VFSS than in those with normal VFSS. We did not find a significant impact of age on PhCI in our pediatric populations.

Comprehensive Manometric Evaluation of Dysphagia in Patients with Down Syndrome.

Dysphagia is a common symptom in children with Down syndrome and is conventionally evaluated with imaging and endoscopy; high-resolution manometry is not routinely utilized. The aim of this study was to describe and correlate pharyngeal and esophageal manometry findings with contrast studies and endoscopy in patients with Down syndrome and dysphagia. Electronic medical records of patients with Down syndrome with dysphagia seen at our center between January 2008 and January 2022 were reviewed. Data collected included demographics, co-morbidities, symptoms, imaging, endoscopy, and manometry. Twenty-four patients with Down syndrome [median age of 14.9 years (IQR 7.6, 20.5), 20.8% female] met inclusion criteria. Common presenting symptoms of dysphagia included vomiting or regurgitation in 15 (62.5%) patients, and choking, gagging, or retching in 10 (41.7%) patients. Esophageal manometry was abnormal in 18/22 (81.2%) patients. The most common findings were ineffective esophageal motility in 9 (40.9%) followed by esophageal aperistalsis in 8 (36.4%) patients. Rumination pattern was noted in 5 (22.8%) patients. All 6 (25%) patients who previously had fundoplication had esophageal dysmotility. Strong agreement was noted between upper gastrointestinal studies and high-resolution esophageal manometry (p = 1.0) but no agreement was found between pharyngeal manometry and video fluoroscopic swallow studies (p = 0.041). High-resolution pharyngeal and esophageal manometry provide complementary objective data that may be critical in tailoring therapeutic strategies for managing patients with Down syndrome with dysphagia.

Accuracy of High-Resolution Pharyngeal Manometry Metrics for Predicting Aspiration and Residue in Oropharyngeal Dysphagia Patients with Poor Pharyngeal Contractility.

Several physiological metrics can be derived from pharyngeal high-resolution impedance manometry (HRPM), but their clinical relevance has not been well established. We investigated the diagnostic performance of these metrics in relation to videofluoroscopic (VFS) assessment of aspiration and residue in patients with oropharyngeal dysphagia. We analyzed 263 swallows from 72 adult patients (22-91 years) with diverse medical conditions. Metrics of contractility, upper esophageal sphincter (UES) opening and relaxation, flow timing, intrabolus distension pressure, and a global Swallow Risk Index (SRI) were derived from pressure-impedance recordings using pressure-flow analysis. VFS data were independently scored for airway invasion and pharyngeal residue using the Penetration-Aspiration Scale and the Normalized Residue Ratio Scale, respectively. We performed multivariate logistic regression analyses to determine the relationship of HRPM metrics with radiological outcomes and receiver-operating characteristic (ROC) analysis to evaluate their diagnostic accuracy. We identified aspiration in 25% and pharyngeal residue in 84% of the swallows. Aspiration was independently associated with hypopharyngeal peak pressure < 65 mmHg (HypoPeakP) [adjusted odds ratio (OR) 5.27; 95% Confidence Interval (CI) (0.99-28.1); p = 0.051], SRI > 15 [OR 4.37; 95% CI (1.87-10.2); p < 0.001] and proximal esophageal contractile integral (PCI) < 55 mmHg·cm·s [OR 2.30; 95% CI (1.07-4.96); p = 0.034]. Pyriform sinus residue was independently predicted by HypoPeakP < 65 mmHg [OR 7.32; 95% CI (1.93-27.7); p = 0.003], UES integrated relaxation pressure (UES-IRP) > 3 mmHg [OR 2.96; 95% CI (1.49-5.88); p = 0.002], and SRI > 15 [OR 2.17; 95% CI (1.04-4.51); p = 0.039]. Area under ROC curve (AUC) values for individual HRPM metrics ranged from 0.59 to 0.74. Optimal cut-off values were identified. This study demonstrates the diagnostic value of certain proposed and adjunct HRPM metrics for identifying signs of unsafe and inefficient bolus transport in patients with oropharyngeal dysphagia.

Effect of Lidocaine on Comfort and Swallowing Pressures During Pharyngeal High-Resolution Manometry.

The purpose of this study is to determine the level of patient comfort during pharyngeal high-resolution manometry (HRM) with and without the use of atomized lidocaine. A secondary aim of the study was to explore whether differences in pharyngeal pressure measurements exist between HRM conducted with the use of atomized lidocaine verses HRM conducted without. Twenty-nine participants underwent two HRM procedures under two conditions, 5-7 days apart: 2% viscous lidocaine to nares or 0.4 mL 4% atomized and 2% viscous lidocaine to nares. During each procedure, participants received six boluses of water. Following catheter removal, participants were asked to rate comfort using a visual analog scale (VAS) and upon completion of both conditions, participants indicated which procedure they preferred. A paired t-test was used to compare pharyngeal pressure measurements at the velopharynx, tongue base region and during upper esophageal sphincter opening. Pharyngeal pressures were categorized as normal or outside of normal limits and compared using a McNemar's test. Twenty-eight of the 29 participants indicated they preferred the use of atomized lidocaine. VAS ratings yielded a significant difference (p = 0.001). No significant difference in pharyngeal pressures were detected between the two groups. Patients prefer atomized lidocaine when undergoing HRM. The use of atomized lidocaine did not affect measurement outcomes.

Polysomnography with an epiglottic pressure catheter does not alter obstructive sleep apnea severity or sleep efficiency.

Pharyngeal and oesophageal manometry is used clinically and in research to quantify respiratory effort, upper-airway mechanics and the pathophysiological contributors to obstructive sleep apnea. However, the effects of this equipment on respiratory events and sleep in obstructive sleep apnea are unclear. As part of a clinical trial (ANZCTRN12613001106729), data from 28 participants who successfully completed a physiology night with an epiglottic catheter and nasal mask followed by a standard in-laboratory polysomnography were compared. The apnea-hypopnea index was not different during the physiology night versus standard polysomnography (22 ±â€…14 versus 23 ±â€…13 events per hr, p = 0.71). Key sleep parameters were also not different compared between conditions, including sleep efficiency (79 ±â€…13 versus 81 ±â€…11%, p = 0.31) and the arousal index (26 ±â€…11 versus 27 ±â€…11 arousals per hr, p = 0.83). There were, however, sleep stage distribution changes between nights with less N3 and rapid eye movement sleep and more N1 on the physiology night, with no difference in N2 (53 ±â€…15 versus 48 ±â€…9, p = 0.08). However, these changes did not increase next-day sleepiness. These findings indicate that while minor sleep stage distribution changes do occur towards lighter sleep, epiglottic manometry does not alter obstructive sleep apnea severity or sleep efficiency. Thus, epiglottic manometry can be used clinically and to collect detailed physiological information for research without major sleep disruption.

Pharyngeal Swallowing During Wake and Sleep.

Sleep is associated with stages of relative cortical quiescence, enabling evaluation of swallowing under periods of reduced consciousness and, hence, absent volition. The aim of this study was to measure and characterize changes in the characteristics of pharyngeal swallows during sleep and wake using high-resolution manometry (HRM). Pharyngeal swallows were recorded with a ManoScan™ HRM in wake-upright, wake-supine, and sleep conditions in 20 healthy participants (mean 27 years; range 21-52). Velopharyngeal and hypopharyngeal segments were analysed separately. Contractile integral, mean peak pressure, inverse velocity of superior-to-inferior pharyngeal pressure, and time to first maximum pressure were analysed with custom-designed software. The supine-wake condition was compared to both upright-wake and sleep conditions using linear mixed effects models. No significant differences were found between supine-wake and upright-wake conditions on any measures. The mean peak pharyngeal pressure was lower during sleep than during the supine-wake condition for both the velopharynx (- 60 mmHg, standard error [SE] = 11, p < 0.001) and hypopharynx (- 59 mmHg, SE = 9, p = 0.001), as was the pharyngeal inverse velocity (- 12 ms/cm, SE = 4, p = 0.012) for the hypopharyngeal segment and the pharyngeal contractile integral (- 32 mmHg s cm, SE = 6, p < 0.001). No significant differences were found in time to the first pharyngeal maximum pressure. This study used HRM to characterize and compare pharyngeal pressures during swallowing in both wake and sleep conditions. No differences were found between upright and supine awake conditions, a finding important to pharyngeal manometric measures made during supine positioning, such as in fMRI. Higher pressures and longer time-related measures of volitional pharyngeal swallowing when awake indicate that cortical input plays an important role in modulation of pharyngeal swallowing.

Comparison of unidirectional and circumferential manometric measures within the pharyngoesophageal segment: an exploratory study.

BACKGROUND: Notable differences have been identified between low-resolution manometry (LRM) and high-resolution manometry (HRM) in normative data. OBJECTIVE: This study aimed to investigate within-subject differences between unidirectional LRM and circumferential HRM solid-state measurement sensors in the pharyngoesophageal segment during swallowing. METHODS: Ten healthy subjects (mean 26.9 years) were evaluated with both a 2.10 mm unidirectional catheter and a 2.75 mm circumferential catheter, with randomized order of catheter placement. Unidirectional measurements were made in four directions (posterior, anterior, right-lateral, left-lateral). Pressures and durations were analyzed to compare (1) posterior to anterior and lateral recordings and (2) posterior and average-LRM measures (C-LRM) to HRM measures at same anatomical location. RESULTS: No significant differences were found in any of the measures across the four radial directions. A lower amplitude was measured in C-LRM compared to HRM for pharyngeal sensors (LRM Sensor 1: - 39.7 mmHg; Sensor 2: - 61.4 mmHg). Compared with posterior-LRM, HRM recorded higher UES pressures (- 12.8 mmHg) and longer UES relaxation durations (- 0.31 s). CONCLUSION: This exploratory study is the first to compare within-subject pressures between unidirectional LRM and circumferential HRM. Substantial differences in pharyngeal manometric measures were found, particularly with regard to UES function. This is clinically important as manometry is uniquely able to evaluate UES function and clarify differential diagnoses in patients with dysphagia.

Pharyngeal peristaltic pressure variability, operational range, and functional reserve.

The present understanding of pharyngeal motor function remains incomplete. Among the remaining gaps of knowledge in this regard is the magnitude of variability of pharyngeal peristaltic pressure amplitude. Although variability can pose difficulty in interpretation of manometric findings, its magnitude can inform the operational range and reserve of the pharyngeal contractile function. We aimed to define the intra- and intersubject and intersession variability of select pharyngeal manometric parameters and, using this information, determine the number of swallow repetitions for acquiring reliable pharyngeal manometric data. We recorded pharyngeal peristalsis in 10 healthy subjects (age: 50 ± 25 yr, 5 women) by high-resolution manometry during two separate sessions of 20 sequences of 0.5-ml water swallows. Two-way ANOVA showed significant variation in the mean peak peristaltic pressure value across sites (P < 0.0001) as well as within the data at each site (P < 0.0001). Similarly, the pharyngeal contractile integral exhibited significant inter- (P = 0.003) and intrasubject (P < 0.001) variability. The Shapiro-Wilk normality test showed mixed results, in that some sites showed normally distributed data, whereas others did not. A robust Monte Carlo simulation showed that the nominal sample size was different for various tested metrics. For a power of 0.8, commonly accepted as an adequate threshold for acceptable statistical power, the optimal sample size for various peristaltic parameters ranged between 3 and 15. There is significant intra- and intersubject variability in site-specific and integrated parameters of pharyngeal peristalsis. The observed variance indicates a significant operational range and reserve in pharyngeal contractile function while necessitating parameter-specific sample size for reliable results.NEW & NOTEWORTHY Intra- and intersubject variability are significant and different at various sites within the contractile pharynx. In addition, significant swallow-to-swallow and subject-to-subject variability exists in pharyngeal contractile integral. The range of intrasubject variability indicates the existence of broad operational range and reserve. Lastly, our variability studies informed Monte Carlo and power analyses, yielding estimates of sample size that would ensure accurate representation of pressure metric variability.

Assessing Upper Esophageal Sphincter Function in Clinical Practice: a Primer.

The upper esophageal sphincter constitutes an important anatomic and functional landmark in the physiology of pharyngeal swallowing. A variety of clinical circumstances may call for a dedicated evaluation of this mechanism, from the etiologic evaluation of indeterminate symptoms to the generation of complex locoregional therapeutic strategies. Multiple diagnostic tools exist for the assessment of pharyngeal swallowing generally and of upper esophageal sphincter function specifically, some well established and others not yet settled into routine practice. This report reviews five specific modalities for use in making this assessment, outlining the strengths, weaknesses, and logistical considerations of each with respect to its potential use in clinical settings. In many cases, these studies will provide complementary information regarding pharyngeal function, suggesting the relative advantage of a multimodal evaluation.

Evaluation of the pharynx and upper esophageal sphincter motility using high-resolution pharyngeal manometry for Parkinson's disease.

Parkinson's disease (PD) is associated with a high incidence of dysphagia. Aspiration pneumonia due to dysphagia is a major cause of death in patients with PD, and therefore accurately evaluating dysphagia should help improve prognosis. It has been reported that the severity of dysphagia does not always correlate with the Hoehn and Yahr (H&Y) stage for classifying PD severity. However, no reports have quantitatively evaluated the relationship between severity of dysphagia and H&Y stage. High-resolution pharyngeal manometry (HRPM) is a quantitative method that can be used to measure swallowing pressure from the velopharynx to the entry of the upper esophageal sphincter (UES). We used HRPM to measure swallowing pressure in 51 patients with PD. As PD progresses, atrophy and degeneration of the pharyngeal muscles become more pronounced, which contributes to dysphagia. However, thus far there is no quantitative clinical evidence for this pathological change. To evaluate the relationship between severity of underlying PD and dysphagia, patients were categorized by H&Y stage, as follows: stage II in four patients, stage III in 23, stage IV in 14, and stage V in 10. In patients with H&Y stages II, III, IV, and V, the respective velopharyngeal pressures were 179.8 ± 32.5, 157.6 ± 62.2, 172.2 ± 48.9, and 107.4 ± 44.0 mmHg, the mesopharyngeal pressures were 126.8 ± 53.2, 121.6.1 ± 50.4, 142.1 ± 57.8, and 61.4 ± 19.6 mmHg, the residual UES pressure were -8.0 ± 10.8, 10.3 ± 16.1, 16.5 ± 37.9, and 11.2 ± 16.2 mmHg, and the resting UES pressure were 49.5 ± 30.0, 15.8 ± 25.7, 1.85 ± 14.1, and -1.2 ± 12.2 mmHg. Patients with severe PD demonstrated significantly decreased velopharyngeal and oropharyngeal pressures, along with incomplete UES opening and contraction. HRPM can detect subtle abnormalities by quantifying swallowing pressure in patients with PD. Evaluating swallowing pressure with HRPM provides insights into neuromuscular dysfunction that causes abnormal pressure generation during pharyngeal swallowing in patients with PD.

Effects of Aspiration Prevention Surgery on the Dynamics of the Pharynx and Upper Esophageal Sphincter.

OBJECTIVE: Oral intake after aspiration prevention surgery (APS) is influenced by postoperative pharyngeal pressure and the dynamics of the upper esophageal sphincter (UES). We examined the effects of less invasive APS combined with UES relaxation techniques (laryngeal closure with cricopharyngeal myotomy [LC-CPM] and central-part laryngectomy [CPL]) on pharyngeal pressure and UES dynamics. STUDY DESIGN: Retrospective, observational study. SETTING: Single center. METHODS: We assessed the high-resolution pharyngeal manometric parameters of patients who underwent APS from 2018 to 2020. Then, we compared the effects of bilateral cricopharyngeal myotomy (combined with LC: LC-CPM group) and total cricoidectomy (CPL group) on both pharyngeal pressure and UES dynamics pre- and postoperatively. RESULTS: Eighteen patients (median age, 68 years; 17 men [94%]) were enrolled. Primary diseases associated with severe aspiration were neuromuscular disorders in 13, stroke in 3, and others in 2 patients. Pharyngeal swallowing pressure did not significantly change before and after APS. UES resting pressure and UES relaxation duration were significantly reduced (P < .001) and prolonged (P < .001), respectively, after APS. Only the CPL group (8 patients: median 62 years, all men) showed an increase in the velopharyngeal closure integral after APS (P < .05). More prolonged UES relaxation duration was recognized postoperatively in the CPL group (P < .01) than in the LC-CPM group. CONCLUSION: Less invasive APS minimally affects pharyngeal swallowing pressure, decreases UES resting pressure, and prolongs UES relaxation duration. CPL may be more effective for postoperative UES relaxation in patients with a short UES relaxation time.

The Role of Imaging Modalities in Diagnosing Dysphagia: A Clinical Review.

Dysphagia, which is characterized by difficulty in oro-gastric bolus transit, is a common condition. It is broadly classified into oropharyngeal or esophageal pathology. A wide array of differentials for dysphagia and initial clinical suspicion of oropharyngeal or esophagus etiology can assist in further evaluation. Fiberoptic endoscopic evaluation of swallowing (FEES) and videofluoroscopic swallow study (VFSS) are the preferred modalities for assessing oropharyngeal bolus transit, residual, as well as determining the risk of laryngeal aspiration. High-resolution pharyngeal manometry (HRPM) is an emerging modality for optimal topographical and pressure assessment of pharyngeal anatomy. HRPM provides improved assistance in evaluating the strength of the pharyngeal muscular contraction. Esophagogastroduodenoscopy (EGD) is the preferred exam for patients with suspected esophageal etiology of dysphagia. Barium swallow provides luminal assessment and assists in evaluating esophageal motility; it is non-invasive, but therapeutic interventions like biopsy cannot be performed. High-resolution esophageal manometry (HREM) has added another dimension in the diagnosis of esophageal motility disorders. The purpose of this review article is to help internists and primary care providers get a better understanding of the role of various imaging modalities in diagnosing dysphagia in the elderly population. This article also provides a comprehensive review and detailed comparison of these imaging modalities based on the latest evidence.

Effect of topical nasal anesthetic on swallowing in healthy adults: A double-blind, high-resolution manometry study.

OBJECTIVE: Topical nasal anesthetic (TNA) is used when evaluating pharyngeal swallowing with high-resolution manometry (HRM). It is unclear if desensitizing the nasal mucosa improves procedure tolerability or affects pharyngeal pressure. This study evaluated the effects of TNA on comfort and pharyngeal pressure using HRM. METHODS: A double-blinded study was conducted with 20 healthy participants ( x¯ = 27 years). Participants performed five saliva and five 10-mL swallows during two exams with ManoScan HRM ESO catheter (Medtronic, Minneapolis, MN) randomized under placebo (nonanesthetic lubricant) and anesthetized (0.4 mL of 2% viscous lidocaine hydrochloride) conditions. Comfort was rated using a 100-mm visual analog scale (VAS). Pharyngeal HRM amplitude and timing were analyzed. RESULTS: VAS ratings were similar under placebo (mean = 38.4, standard deviation [SD] = 19.92) and TNA conditions (mean = 33.78, SD = 18.9), with no significant differences between placebo and anesthetized conditions (t[19] = 1.23, P = 0.23) or tolerability at first and second procedure (t[19] = 1.38, P = 0.18). Lower maximum and mean pharyngeal pressure were found for the TNA condition when compared to placebo (dry: maximum [-15.45 mmHg, standard error (SE) = 5.06 mmHg, P = 0.021]; mean [-5.22 mmHg, SE = 1.58 mmHg, P = 0.005]), and (liquid: maximum [-14.79 mmHg, SE = 5.01 mmHg, P = 0.010]; mean [-2.79 mmHg, SE = 1.99 mmHg, P = 0.008]). CONCLUSION: This double-blind, randomized study is the first to investigate effects of TNA on tolerability and pharyngeal pressure using HRM. Results indicate TNA offered no significant difference in procedure comfort while affecting the magnitude of pharyngeal swallowing. LEVEL OF EVIDENCE: 4. Laryngoscope, 128:1335-1339, 2018.

Characterization of pharyngeal peristaltic pressure variability during volitional swallowing in healthy individuals.

BACKGROUND: Recent technological advances incorporated in high resolution manometry have justifiably heightened interest in manometric evaluation of the pharynx. Despite this interest, from both physiologic and clinical perspective there remain a number of unanswered questions regarding the magnitude of variability of pharyngeal pressure phenomena. Therefore, the aim of the present study was to characterize in healthy individuals the inter-subject and recording-site specific variability of pharyngeal peristaltic pressure phenomena. METHODS: We studied 32 healthy subjects (age: 21-83 years,20 under 35 years) during dry,5 and 10 mL water swallows ×3. Pharyngeal peristaltic pressures were recorded using a high resolution (HR) manometric system and a catheter assembly with 36 circumferential sensors spaced at 1 cm intervals positioned trans-nasally to traverse the pharynx, UES and proximal esophagus. KEY RESULTS: Both site-specific pressure data and the Pharyngeal contractile integral (PhCI) showed wide dispersion ranging between values under 50 mm Hg to over 300 mm Hg and 100-600 mm Hg/cm/s,respectively. There was also wide range of dispersion of data for both the standard deviations and the coefficient of variation for all sites (P=.001). The coefficient of variation for PhCI ranged between 0.02 and 0.25 representing data dispersion of 2-25 percent of the mean among subjects (P=.001). Position, age and volume of swallowed fluid did not influence the magnitude of variability. CONCLUSIONS: Deglutitive Pharyngeal peristalsis generates pressures with significant degree of site-related and inter-subject variability. This variability is not influenced by age, position and volume of swallowed fluid.

Characterization and correction of pressure drift in the ManoScan(™) high-resolution manometry system: In vitro and in vivo.

BACKGROUND: A substantial pressure drift in high-resolution manometry (HRM) has been reported; however, fundamental questions remain regarding the origin and management of this drift. The aim of this study was to provide critical in-depth analyses of ManoScan(™) HRM drift in vitro and in vivo. METHODS: A total of sixteen 15-min studies and twelve 5-h studies were performed in a water bath at 37 °C at 4.0 cm depth (2.9 mmHg) with ESO and ESO Z catheters. Six 5-h in vitro studies were performed similarly at a depth of 9.0 cm (6.6 mmHg). Eight 15-min studies and nine 8-h in vivo studies were performed with healthy participants. Two correction methods - thermal compensation (TC) and interpolated thermal compensation (ITC) - were tested. KEY RESULTS: Overall pressure drift varied both between studies (p < 0.01) and within sensors (p < 0.01). Drift resulted from thermal shock, an initial pressure change at intubation, and baseline drift, a linear drift over time (R(2)  > 0.96). Contrary to previous reports, there was no correlation between drift and average (r = -0.02) or maximum pressure exposure (r = -0.05). Following data correction, ITC had the lowest median error but persisted with a maximum error of 2.5 mmHg (IQR = 3.0). CONCLUSIONS & INFERENCES: The substantial drift in the ManoScan(™) HRM system is highly variable and not corrected via the standard operating instructions. ITC has superior performance but requires communication with the manufacturer to enable this option. This has a substantial impact on clinical diagnosis, utility of existing normative data, and future research of HRM.

Pharyngeal pressure differences between four types of swallowing in healthy participants.

PURPOSE: The aim of this observational study was to identify biomechanical differences, as measured by pharyngeal manometric pressure patterns, between discrete and continuous water swallowing, as well as volitionally initiated and reflexive swallowing. METHODS: Using pharyngeal manometry, swallowing-related pressures from 24 young healthy individuals were recorded at three locations: upper pharynx, mid-pharynx and upper oesophageal sphincter (UES) during four swallowing conditions: discrete saliva swallowing, discrete 10ml water swallowing, volitional continuous water swallowing, and reflexive continuous water swallowing. Measures of peak pressure and pressure duration at each level were compared across conditions using repeated-measures analysis of variance. RESULTS: UES nadir pressure during saliva swallowing was lower than during water swallowing conditions (p<0.05). In addition, nadir pressure during discrete 10ml water swallowing was lower than during reflexive and volitional continuous water swallowing conditions (p<0.05). Saliva swallowing produced longer pressure duration than water swallowing conditions at the upper pharynx (p<0.05). Saliva swallowing produced pressure of greater duration than reflexive continuous water swallowing at mid-pharynx (p<0.05). Further, discrete 10ml water swallowing produced longer UES opening duration and longer pharyngeal pressure generation (p<0.05) than reflexive continuous water swallowing or saliva swallowing. CONCLUSION: Pressure generation differs between swallowing types and bolus types at the level of the UES in particular. These physiological differences between swallowing and bolus types may support clinical decisions for individuals with impaired swallowing.

The capacity for volitional control of pharyngeal swallowing in healthy adults.

INTRODUCTION: Previous research has documented that pressure and duration of brainstem-generated pharyngeal swallowing can be cortically modulated. But there is a commonly held belief that the sequence of pharyngeal pressure remains constant. However, Huckabee et al. [19] reported a patient cohort who demonstrated reduced latency of peak pressure in the proximal and distal pharynx, disproportionate and sometimes inversely correlated with overall swallowing duration, suggesting independent timing of underlying muscle contraction within the overall pharyngeal response. This study examined if healthy adults can volitionally produce altered latency of pharyngeal closure in isolation following intensive training, thereby evaluating the capacity for pharyngeal adaptation in a healthy system. METHOD: Six healthy participants were seen for intensive training, consisting of daily one-hour sessions over two weeks (10 days) using pharyngeal manometry as a visual biofeedback modality. The participants were instructed to produce simultaneous pressure in the pharyngeal sensors when swallowing. The temporal separation of peak proximal and distal pharyngeal pressure was measured with discrete-sensor pharyngeal manometry at baseline, during training with biofeedback, and following training without biofeedback. RESULTS: Following intensive training, participants were able to reduce temporal separation of peak pressure between the proximal and distal pharyngeal sensors from a baseline median of 188 ms (IQR=231 ms) to 68 ms (IQR=92 ms; p=0.002). In contrast, there was no significant change in overall swallowing duration during training (p=0.41). However, change in pharyngeal pressure latency was moderately correlated with both change in swallowing duration (r=0.444) and amplitude (r=0.571) during training, and there was a reduction in swallowing duration post-training (p=0.03). CONCLUSION: Given intensive manometric biofeedback training, participants substantially reduced temporal separation of peak proximal and distal pharyngeal pressure when volitionally swallowing. However, correlation with overall pressure and duration measures suggest the adaptation was one of modulating the cumulative pharyngeal response rather than altering discrete components of timing of pharyngeal pressure in isolation. This is inconsistent with the pattern of behaviour documented by Huckabee et al. [19] in the patient population. Further research on modulatory control over targeted aspects of the pharyngeal swallow is needed, and may provide avenues for rehabilitative treatment of patients with dysphagia.

Electrical bioimpedance measurement as a tool for dysphagia visualisation.

A non-invasive and portable bioimpedance method and a device for detecting superior to inferior closure of the pharynx during swallowing have been developed. The 2-channel device measures electric impedance across the neck at two levels of the pharynx via injected currents at 40 and 70 kHz. The device has been trialled on both healthy and dysphagic subjects. Results from these trials revealed a relationship (r = 0.59) between the temporal separation of the second peaks in the bioimpedance waveforms and descending pressure sequence in the pharynx as measured by pharyngeal manometry. However, these features were only clearly visible in the bioimpedance waveforms for 64% of swallows. Further research is underway to improve the bioimpedance measurement reliability and validate waveform feature correlation to swallowing to maximise the device's efficacy in dysphagia rehabilitation.