Pharyngeal (Zenker's) diverticulum is a disorder of upper esophageal sphincter opening.

Pharyngeal coordination, sphincter opening, and flow pressures during swallowing were investigated in patients with pharyngeal (Zenker's) diverticula. Fourteen patients with diverticula and 9 healthy age-matched controls were studied using simultaneous videoradiography and manometry. Pharyngeal and upper esophageal sphincter pressures were recorded by a perfused side hole/sleeve assembly. Temporal relationships among swallowing events, extent of sphincter opening during swallowing, and intrabolus pressure during bolus passage across the sphincter were measured. The timing among pharyngeal contraction and sphincter relaxation, opening, and closure did not differ between patients and controls. Sphincter opening was significantly reduced in patients compared with controls in sagittal (P = 0.0003) and transverse (P = 0.005) planes. Manometric sphincter relaxation was normal in patients. Intrabolus pressure was significantly greater in patients than in controls (P = 0.001). It is concluded that Zenker's diverticulum is a disorder of diminished upper esophageal sphincter opening that is not caused by pharyngosphincteric incoordination or failed sphincter relaxation. Incomplete sphincter opening is likely to cause dysphagia. Increased hypopharyngeal pressures during swallowing are probably important in the pathogenesis of the diverticulum.     

Pharyngeal clearance during swallowing: a combined manometric and videofluoroscopic study.

The deglutitive pharyngeal contraction was analyzed using simultaneous videofluoroscopic and manometric studies of eight volunteers. Anterior, posterior, and longitudinal movements of the pharyngeal surfaces, relative to the cervical vertebrae, were measured during swallows of 5 and 10 mL of liquid barium. Profound pharyngeal shortening during bolus transit through the pharynx eliminated access to the larynx and elevated the upper esophageal sphincter to within 1.5 cm of the retrolingual pharynx. Bolus head movement through the pharynx preceded the propagated pharyngeal contraction and registered manometrically as a slight intrabolus pressure before the major pressure complex. Contraction in the horizontal plane began after bolus head transit and culminated with stripping of the bolus tail through the pharynx. Prolonged upper sphincter opening with the larger-volume swallows resulted from a delayed onset rather than altered propagation of the horizontal pharyngeal contraction. It is concluded that the propagated pharyngeal contraction facilitates pharyngeal clearance but has a minimal role in the process of bolus propulsion during swallowing. The propagated contraction works in concert with profound pharyngeal shortening to minimize hypopharyngeal residue after a swallow.     

Biomechanics of cricopharyngeal bars

Patients with a prominent cricopharyngeal bar visible on radiography are generally considered to have spasm of the cricopharyngeus, which is the major muscle component of the upper esophageal sphincter. This condition has been termed "cricopharyngeal achalasia." The aim of this study was to determine the pathogenesis of cricopharyngeal bars. Concurrent videofluoroscopic and manometric examinations of the pharynx and upper esophageal sphincter were performed in a cohort of six patients with prominent cricopharyngeal bars and in eight control volunteers. In each subject, swallows of 2-30-mL barium boluses were recorded. The patients with cricopharyngeal bars showed (a) normal peristaltic contraction in the pharynx, (b) normal axial upper esophageal sphincter pressure and relaxation, (c) normal flow rate across the upper esophageal sphincter, and (d) normal duration of upper esophageal sphincter opening for different bolus volumes. The major abnormalities in the patients with cricopharyngeal bars were (a) reduced maximal dimensions of the upper esophageal sphincter during the transsphincteric flow of barium and (b) increased intrabolus pressure upstream to the upper esophageal sphincter. Thus, the increase in intrabolus pressure preserved normal transsphincteric flow rates even though the upper esophageal sphincter did not open normally. Overall, the constellation of findings in the patients studied suggests that the underlying pathogenesis of their cricopharyngeal bar was reduced muscle compliance wherein the relaxed cricopharyngeus did not distend normally during swallowing.     

Upper esophageal sphincter function during deglutition

Upper esophageal sphincter function was investigated during swallows of graded volumes in 8 normal volunteers. Concurrent recordings of video-fluoroscopic and manometric studies were obtained and correlated with each other by means of a videotimer. Maximal upper esophageal sphincter (UES) pressure was typically located 1.5 cm distal to the air-tissue interface between the hypopharynx and the proximal margin of the sphincter. The region in which UES pressure was greater than or equal to 50% maximal averaged 1.0 cm in length. Thus, the physiologic high-pressure zone of the UES corresponds in size and location to that of the cricopharyngeus muscle. Fluoroscopic analysis of sphincter movement indicated that the sphincter high-pressure zone moved 2.0-2.5 cm orally during swallowing and that the magnitude of the orad movement was directly related to the volume of barium swallowed. The maximal anterior-posterior diameter of sphincter opening during a swallow ranged from 0.9 to 1.5 cm and was also directly related to the volume swallowed. The intervals of UES opening and relaxation increased significantly with increasing bolus volume; the duration of UES relaxation ranged from a mean of 0.37 s for dry swallows to 0.65 s for 20-ml swallows. Thus, the dynamics of UES function during deglutition are dependent upon the volume of the swallowed bolus. Larger bolus volumes are accommodated by both an increased diameter of sphincter opening and by prolongation of the interval of sphincter relaxation. Analysis of the timing of other reference points within the pharyngeal swallow sequence indicated that as the manometric interval of UES relaxation increased, the period of laryngeal elevation was prolonged, the UES relaxed earlier and contracted later, and the interval between the onset of laryngeal elevation and hypopharyngeal contraction increased.     

The Effect of Voluntary Pharyngeal Swallowing Maneuvers on Esophageal Swallowing Physiology

The purpose of our study was to evaluate whether swallowing maneuvers designed to impact pharyngeal physiology would also impact esophageal physiology. Healthy volunteers underwent high-resolution manometry while performing three randomized swallowing maneuvers with and without a 5-ml bolus: normal swallowing, Mendelsohn maneuver, and effortful swallowing. We examined esophageal parameters of peristaltic swallows, hypotensive or failed swallows (“nonperistaltic swallows”), distal contractile integral (DCI), contractile front velocity (CFV), intrabolus pressure, and transition zone (TZ) defect. Four females and six males (median age 39 years; range 25–53) were included in the study. The overall number of nonperistaltic swallows was 21/40 (53 %) during normal swallowing, 27/40 (66 %) during the Mendelsohn maneuver, and 13/40 (33 %) during effortful swallowing. There were significantly more overall nonperistaltic swallows with the Mendelsohn maneuver compared with effortful swallowing (p = 0.003). While swallowing a 5-ml bolus, there were more nonperistaltic swallows during the Mendelsohn maneuver (12/20, 60 %) compared to that during normal swallowing (6/20, 30 %) (p = 0.05) and more peristaltic swallows during effortful swallowing as compared to Mendelsohn maneuver (p = 0.003). Intrabolus esophageal pressure was greater during the Mendelsohn maneuver swallows in the bolus-swallowing condition as compared to normal swallowing (p = 0.02). There was no statistical difference in DCI, CFV, or TZ defect between swallowing conditions. The Mendelsohn maneuver may result in decreased esophageal peristalsis while effortful swallowing may improve esophageal peristalsis. Because it is important to understand the implications for the entire swallowing mechanism when considering retraining techniques for our patients, further investigation is warranted.     

Predictors of Outcome following Cricopharyngeal Disruption for Pharyngeal Dysphagia

The indications for, and predictors of outcome following cricopharyngeal disruption in pharyngeal dysphagia are not clearly defined. Our purpose was to examine the symptomatic response to cricopharyngeal disruption, by either myotomy or dilatation, in patients with oral-pharyngeal dysphagia and to determine pretreatment manometric or radiographic predictors of outcome. Using simultaneous pharyngeal videoradiography and manometry, we studied 20 patients with pharyngeal dysphagia prior to cricopharyngeal diltation (n = 11) or myotomy (n = 8), and 23 healthy controls. We measured peak pharyngeal pressure, hypopharyngeal intrabolus pressure, upper esophageal sphincter diameter, and coordination. Response rate to sphincter disruption was 65%. The extent of sphincter opening was significantly reduced in patients compared with controls (p= 0.004), but impaired sphincter opening was not a predictor of outcome. Increased hypopharyngeal intrabolus pressures (>19 mmHg for 10 ml bolus; >31 mmHg for 20 ml bolus) was a significant predictor of outcome (p= 0.01). Neither peak pharyngeal pressure nor incoordination were predictors of outcome. In pharyngeal dysphagia, hypopharyngeal intrabolus pressure, and not peak pharyngeal pressure, is a predictor of response to cricopharyngeal disruption. The relationship between intrabolus pressure and impaired sphincter opening is an indirect measure of sphincter compliance which helps predict therapeutic response.     

Sequence Variability During Hypopharyngeal Bolus Transit

The pharyngeal phase of deglutition is considered to occur in a reflexive, preprogrammed fashion. Previous studies have determined a general sequence of events based on the mean timing of bolus transit and swallowing gestures. Individual variability has not been studied, however. The purpose of this study was to determine the amount of sequence variability that normally occurs during the hypopharyngeal phase of deglutition. Dynamic swallow studies from 60 normal volunteers were evaluated and event sequence variability was determined for 12 two-event sequences during swallowing of three bolus sizes. There was found to be some variability in event sequences for almost all events evaluated except for the following : (1) arytenoid cartilage elevation always began prior to opening of the upper esophageal sphincter, (2) the sphincter always opened prior to the arrival of the bolus at the sphincter, (3) larynx-to-hyoid approximation always occurred after the onset of upper esophageal sphincter opening, and (4) maximum pharyngeal constriction always occurred after maximal distension of the upper esophageal sphincter. Variability was more common during swallowing of the smallest bolus size. This information may be helpful in evaluating event coordination in patients with dysphagia.     

Kinematic and Temporal Factors Associated with Penetration–Aspiration in Swallowing Liquids

In this study we undertook careful analysis of 13 quantitative physiological variables related to oropharyngeal swallowing from a sample of 42 subacute patients referred for dysphagia assessment. Each patient underwent a videofluoroscopic swallowing examination in which they swallowed up to five boluses of 22 % w/v ultrathin liquid barium suspension administered by teaspoon. Our goal was to determine whether scores on 13 kinematic or temporal parameters of interest were independently associated with the presence of penetration–aspiration in the final compiled dataset of 178 swallows. Participants were classified as aspirators based on the presence of at least one swallow that demonstrated a Penetration–Aspiration Scale score of ≥3. The parameters of interest included six kinematic parameters for capturing hyoid position, three swallow durations [laryngeal closure duration, hyoid movement duration, and upper esophageal sphincter (UES) opening duration], and four swallow intervals (laryngeal closure to UES opening, bolus dwell time in the pharynx prior to laryngeal closure, stage transition duration, and pharyngeal transit time). Mixed-model repeated-measures ANOVAs were conducted to determine the association between each parameter and aspiration status. Only 1 of the 13 parameters tested distinguished aspirators from nonaspirators: aspirators demonstrated significantly shorter UES opening duration. In addition, a trend toward reduced maximum superior position of the hyoid was seen in aspirators. Limitations and future considerations are discussed.     

Maximal Hyoid Excursion in Poststroke Patients

Reduced maximal hyoid excursion has been suspected as one of the primary physiologic causes of aspiration after a stroke. Vertical and anterior displacement of hyoid excursion is critical to epiglottic closure for airway protection and the opening of the upper esophageal sphincter (UES). Without these carefully timed and well-executed components, the bolus cannot pass safely through the pharynx. The purpose of this study was to evaluate vertical and anterior displacement of the hyoid bone during oropharyngeal swallowing in two groups of subjects: (1) 16 stroke patients who aspirate before or during the swallow (aspirators), and (2) 33 stroke patients who do not aspirate (nonaspirators). Means and standard deviations for anterior and vertical displacement were analyzed for 5- and 10-ml thin-liquid boluses using the ImageJ program (136 swallows). A two-way analysis of variance (ANOVA) was run with group and volume as independent variables. There was no significant difference between the two groups for vertical or anterior displacement. Maximal anterior displacement of the hyoid bone was slightly longer in nonaspirators than in aspirators. Aspiration before and during the swallow may be related more to the triggering of pharyngeal swallow than to the maximal extent of hyoid excursion.     

Influence of the viscosity of the swallowed food bolus on the motility of the pharynx

In 9 young men, healthy volunteers, we studied the effect of dry swallows, liquid and paste swallows on the pharyngeal motility. The viscosities of liquids and past were 200 centipoise (cP), 300 cP and 60000 cP, respectively. The bolus volume was 10 ml. For pharyngeal manometry we used two strain-gauge manometric probes taped together, so that a total of six transducers were staggered at 1.5 cm intervals. After its passage through the nose, the assembly was positioned so that all its transducers faced posteriorly, and manometric activity was recorded from oropharynx, hypopharynx and upper esophageal sphincter (UES). We also recorded infra-hyoid electromiographic activity. The amplitude and duration of the oropharyngeal and hypopharyngeal peristaltic pressure complex were not changed by the different boluses. The velocity of peristaltism propagation between oropharynx and UES was slower for paste than for liquids or dry swallows. The increased of viscosity was associated with longer duration of UES relaxation, and greater intrabolus pressure in hypopharynx and UES. The infra-hyoid electromiographic activity was longer for paste than for liquids or dry swallows. These findings suggest that pharyngeal motility is affected by the characteristics of the swallowed bolus.     

Timing of videofluoroscopic,manometric events,and bolus transit during the oral and pharyngeal phases of swallowing

The aims of this study were to evaluate and quantify the timing of events associated with the oral and pharyngeal phases of liquid swallows. For this purpose, we recorded 0–20 ml barium swallows in three groups of volunteers using videoradiographic, electromyographic, and manometric methods. The study findings indicated that a leading complex of tongue tip and tongue base movement as well as onset of superior hyoid movement and mylohyoid myoelectric activity occurred in a tight temporal relationship at the inception of swallowing. Two distinct general types of normal swallows were observed. The common “incisor-type” swallow began with the bolus positioned on the tongue with the tongue tip pressed against the upper incisors and maxillary alveolar ridge. At the onset of the “dipper-type” swallow the bolus was located beneath the anterior tongue and the tongue tip scooped the bolus to a supralingual location. Beginning with tongue-tip peristaltic movement at the upper incisors, the two swallow types were identical. Swallow events that occurred after lingual peristaltic movement at the maxillary incisors showed a volume-dependent forward migration in time that led to earlier movement of the hyoid and larynx as well as earlier opening of the upper esophageal sphincter in order to receive the large boluses that arrived sooner in the pharynx during the swallow sequence than did smaller boluses. The study findings indicated that timing of swallow events should be considered in reference to both swallow type and bolus volume. The findings also indicated an important distinction between peristaltic transit and bolus clearance.     

Influence of everyday bolus consistencies in different body positions on high‐resolution esophageal pressure topography (HREPT) parameters

The standard protocol for esophageal manometry involves placing the patient in the supine position with head turned to left (supine head left [SHL]) while evaluating liquid bolus swallows. Routinely, semisolid or solid boluses are not evaluated. Currently, the daily American diet includes up to 40% solid or semisolid texture. Thus far, the data on the effect of different bolus on high‐resolution esophageal pressure topography (HREPT) parameters are scarce. This study aims to evaluate the effect of every day bolus consistencies in different body positions on HREPT variables. HREPT was performed on healthy volunteers with a modified protocol including liquid swallows in the SHL position followed by applesauce (semisolid), cracker (solid), and marshmallow (soft solid) in three different positions (SHL, sitting, and standing). A total of 38 healthy adult subjects (22 males and 16 females, median age = 27, and mean body mass index = 25) were evaluated. The resting upper esophageal sphincter pressure was significantly different while subjects swallowed crackers, applesauce, and marshmallows in most positions compared with liquid SHL (P < 0.05). The lower esophageal sphincter, contractile front velocity, and distal contractile integral pressures did not differ in all different consistencies compared with SHL. The integrated relaxation period was significantly higher with solid bolus compared with liquid bolus only in SHL position. The intrabolus pressure was significantly different with solid and soft solid boluses in all postures compared to liquid SHL. The American diet consistency affects upper esophageal sphincter pressure and partially integrated relaxation period and intrabolus pressure in various positions. Semisolid bolus swallows do not cause substantial pressure changes and are safe for evaluation and maintaining adequate caloric intake in patients with dysphagia who cannot tolerate solids.     

Hyoid motion during swallowing: factors affecting forward and upward displacement

During swallowing, the hyoid bone is described as moving first upward, then forward, then returning to the starting position. This study examined hyoid motion during swallowing of chewed solids and liquids. Barium videofluorography (VFG) was performed on 12 healthy volunteers eating 8-cc portions of various solid foods and drinking liquid. Hyoid position was measured frame-by-frame for 88 swallows relative to the occlusal plane of the upper teeth. The hyoid bone moved both upward and forward during swallowing, but upward displacement was sometimes very small. There was no correlation between the amplitudes of hyoid upward and forward displacements. The amplitude of upward displacement was highly variable, smaller for liquids than for solid foods (p <0.001), and, for solid foods, larger for the first swallow than for the second swallow (p = 0.02). The amplitude of forward displacement did not differ significantly between liquids and solids or between first and second swallows. We conclude that upward displacement of the hyoid bone in swallowing is related primarily to events in the oral cavity, while its forward displacement is related to pharyngeal processes, especially the opening of the upper esophageal sphincter.     

Structural Displacements in Normal Swallowing: A Videofluoroscopic Study

Dynamic videofluoroscopic swallow studies were performed on 60 normal adult volunteers to establish normative data for displacement of upper aerodigestive tract structures during deglutition. Variables evaluated included hyoid bone displacement, larynx-to-hyoid bone approximation, pharyngeal constriction, and the extent of pharyngoesophageal sphincter (PES) opening during liquid swallows of 1, 3, and 20 cc. Results showed direct relationships between bolus size and hyoid displacement, between bolus size and PES opening, and between bolus size and pharyngeal constriction. Only hyoid-to-larynx approximation remained unchanged across bolus sizes. Sex differences were noted for all variables except PES opening. Reliability for most measurement variables was excellent. To our knowledge, normative data for pharyngeal constriction and larynx-to-hyoid approximation have not previously been described.     

Influence of surgery on deglutitive upper oesophageal sphincter mechanics in Zenker's diverticulum.

BACKGROUND/AIMS: To evaluate the role of upper oesophageal sphincter (UOS) compliance in dysphagia, the functional consequences of surgery were evaluated in eight patients with pharyngeal diverticula. The study examined the hypotheses that hypopharyngeal intrabolus pressure is an indicator of UOS compliance and that UOS opening and intrabolus pressure are normalised by surgery. METHODS: In eight patients and nine healthy controls, we measured the timing of swallow events, UOS relaxation, maximal UOS dimensions, intrabolus pressure, and trans-sphincteric bolus flow rates by simultaneous videoradiography and pharyngeal manometry. RESULTS: Bolus flow rates were not changed by surgery. Surgery significantly increased UOS opening (p = 0.0001) and reduced hypopharyngeal intrabolus pressure (p = 0.0001). The slope of the relation between sphincter area and intrabolus pressure was steeper in patients than controls and was normalised by surgery. Surgery had minor effects on basal UOS tone and timing of swallow events. CONCLUSIONS: Upper oesophageal sphincter compliance is poor in Zenker's diverticulum and is normalised by surgery. Hypopharyngeal intrabolus pressure, which correlates with resistance to trans-sphincteric bolus flow, is a useful indicator of UOS compliance. Intrabolus pressure may be a predictor of outcome after myotomy in pharyngeal dysphagia. Cricopharyngeal myotomy is a mandatory component of surgery for Zenker's diverticulum.     

Swallowing Physiology of Toddlers with Long-Term Tracheostomies: A Preliminary Study

This study investigated the swallowing physiology of toddler-aged patients with long-term tracheostomies. Structural movements and motility of the pharyngeal stage of swallowing were studied in four toddlers ranging in age from 1:2 (years:months) to 2:9 with long-term tracheostomies. A patient aged 1:2 years with no tracheostomy served as a toddler model for comparison. Videofluoroscopic recordings of the patients' liquid and puree bolus swallows were analyzed for a) onset times for pharyngeal stage events, laryngeal vestibule closure, and tracheostomy tube movement; b) timeliness of swallow response initiation; and c) pharyngeal transport function. Results found differences in timing of pharyngeal stage movements between the tracheostomized patients and the patient with no tracheostomy. Laryngeal vestibule closure occurred before or within the same 0.033-s video frame as onset of upper esophageal sphincter (UES) opening in the patient with no tracheostomy, but occurred 0.033–.099 s after onset of UES opening in the tracheostomized patients. The time line required to close the laryngeal vestibule once the arytenoids began their anterior movement was longer in the tracheostomized patients than in the patient with no tracheostomy and was associated with laryngeal penetration. The patient with no tracheostomy displayed superior excursion of the arytenoid and epiglottis during the swallowing; the tracheostomized patients did not. No association was found between onset of tracheostomy tube movement and laryngeal vestibule closure. Delayed swallow response initiation was observed across tracheostomized patients at a mean frequency of 45% with associated penetration. Pharyngeal dysmotility was not observed. Findings supported the concept that long-term tracheostomy in toddler-aged patients affects swallowing physiology.     

Effects of Bolus Volume on Pharyngeal Contact Pressure During Normal Swallowing

This cross-sectional study investigated the effect of bolus volume on contact pressure within the pharynx and upper esophageal sphincter (UES). Three solid-state manometric pressure sensors were placed transnasally into the pharynx and the proximal esophagus of 40 participants (gender equally represented and between the ages of 20 and 45 years). Participants completed five repetitions each of three swallowing conditions: 5-, 10-, and 20-ml water bolus swallows. Repeated-measures ANOVA revealed no significant differences in the amplitude of pharyngeal contact pressure between the three swallowing conditions (sensor 1: p = 0.627, sensor 2: p = 0.764). Similarly, for durational measures nonsignificant main effects were found at both sensor 1 (p = 0.436) and sensor 2 (p = 0.350). Significant differences were found in UES pressure between the three conditions of bolus swallows (p = 0.000), with negative pressure in the UES inversely proportionate to bolus volume. However, durational measures of UES relaxation pressure were not significantly different between all conditions (p = 0.473). This study demonstrates no significant pressure differences of amplitude and duration between swallowing conditions in the pharynx. At the level of the UES, smaller boluses generated greater negative pressure.     

Event Sequence Variability in Healthy Swallowing: Building on Previous Findings

This study builds on previous work by Kendall, Leonard, and McKenzie, which investigated event sequence variability for 12 paired events during swallowing by healthy volunteers. They identified four event pairs that always occurred in a stereotyped order and a most common occurring overall order of events during swallowing. In the current study, we investigated overall event sequencing and the same four paired events in a sample of swallows by healthy young (under 45 years old) volunteers. Data were collected during a 16-swallow lateral videofluoroscopy protocol, which included manipulations of bolus volume, barium density, bolus viscosity, and swallow cueing. Our results agreed with previous findings that variable event sequencing is found in healthy swallowing, and, in regard to obligatory sequencing of two paired events, movement of the arytenoids toward the base of the epiglottis begins prior to upper esophageal sphincter (UES) opening and maximum hyolaryngeal approximation occurs after UES opening. However, our data failed to replicate the previous findings that there is obligatory sequencing of maximum pharyngeal constriction after maximal UES distension and the UES opens before bolus arrival at the UES. The most common observed overall event sequence reported by Kendall et al. was observed in only 4/293 swallows in our dataset. Manipulations of bolus volume, bolus viscosity, barium concentration, swallow cueing, and swallow repetitions could not completely account for the differences observed between the two studies.     

Timing Differences Between Cued and Noncued Swallows in Healthy Young Adults

Temporal parameters such as stage transition duration, bolus location at swallow onset, and pharyngeal transit time are often measured during videofluoroscopy, but these parameters may vary depending on assessment instructions. Specifically, “command” (cued) swallows have been observed to alter timing compared to spontaneous (noncued) situations in healthy older adults. The aim of our study was to confirm whether healthy young people show timing differences for thin liquid swallows between cued and noncued conditions. Twenty healthy young adults swallowed 10-cc boluses of ultrathin barium in videofluoroscopy. The cued condition was to hold the bolus in the mouth for 5 s before swallowing. Three noncued swallows were also recorded. In the cued condition, bolus advancement to the pyriform sinuses prior to swallow initiation was seen significantly less frequently. Stage transition durations showed a nonsignificant trend toward being shorter. Pharyngeal transit times and pharyngeal response time (a measure capturing the interval between hyoid movement onset and bolus clearance through the upper esophageal sphincter) were both significantly longer in the cued condition. Our study in healthy young adults confirms findings previously observed in older adults, namely, that swallow onset patterns and timing differ between cued and noncued conditions. In particular, bolus advancement to more distal locations in the pharynx at the time of swallow onset is seen more frequently in noncued conditions. This pattern should not be mistaken for impairment in swallow onset timing during swallowing assessment.     

Effects of Nasogastric Tubes on the Young, Normal Swallowing Mechanism

The present study aimed to investigate the effects of different-sized nasogastric tubes on swallowing speed and function in 10 young normal volunteers. Using X-ray visualization, liquid barium swallows were recorded on video (videofluoroscopy) under three experimental conditions: no nasogastric tube, fine-bore nasogastric tube, and wide-bore nasogastric tube. Nasogastric tubes slowed swallowing but did not alter swallowing function, namely bolus transit and clearance, and airway protection. The presence of a wide-bore nasogastric tube caused significant duration changes in several swallowing measures, namely duration of stage transition, duration of pharyngeal response, duration of pharyngeal transit, and duration of upper esophageal sphincter opening. Similar trends were seen for the fine-bore tube. The implications for nonoral feeding of patients with swallowing disorders are discussed.