Single Swallows Research Articles

Spatiotemporal Visualizations for the Measurement of Oropharyngeal Transit Time From Videofluoroscopy

Videofluoroscopy remains one of the mainstay methods for clinical swallowing assessment, yet its interpretation is both complex and subjective. This, in part, reflects the difficulties associated with estimation of bolus transit time through the oral and pharyngeal regions by visual inspection, and problems with consistent repeatability. This paper introduces a software-only framework that automatically determines the time taken for the bolus to cross 1-D anatomical landmarks representing the oral and pharyngeal region boundaries ( Fig. 1). The user-steered delineation algorithm live-wire and straight-line annotators are used to demarcate the landmark on a frame prior to the swallow action. The rate of change of intensity of the pixels in each landmark is used as the detection feature for bolus presence that can be visualized on a spatiotemporal plot. Artifacts introduced by head and neck movement are removed by updating the landmark coordinates using affine parameters optimized by a genetic-algorithm-based registration method. Heuristics are applied to the spatiotemporal plot to identify the frames during which the bolus passes the landmark. Correlation coefficients between three observers visually inspecting twenty-four 5-mL single swallow clips did not exceed 0.42. Yet the same measurements taken using this framework on the same clips had correlation coefficients exceeding 0.87.

Zenker's diverticulum

A 78-year-old man presented with a 6-month history of dysphagia, regurgitation of food and weight loss. Nasal endoscopy and plain chest radiography were unremarkable. However, a single contrast barium swallow demonstrated the classical appearances of a Zenker's diverticulum (also known as pharyngeal pouch) (Figures 1 and 2).

Lung Volume During Swallowing: Single Bolus Swallows in Healthy Young Adults

This study examined the relationship between swallowing and lung volume initiation in healthy adults during single swallows of boluses differing in volume and consistency. Differences in lung volume according to respiratory phase surrounding the swallow were also assessed. Nine men and 11 women between the ages of 19 and 28 years served as study participants. Lung volume and respiratory phase data were recorded as each participant completed 5 trials each of 10-mL and 20-mL water boluses by cup, and thin and thick paste boluses by spoon, presented in randomized order. Significant differences in lung volume at swallow initiation were found based on bolus consistency but not on bolus volume. No differences were found for lung volume initiation based on the respiratory phase surrounding the swallow or for the respiratory pattern based on bolus volume or consistency. Findings of this study extend the existing knowledge base regarding the interaction of the swallow and respiratory systems by identifying targeted lung volumes at swallow initiation. In addition to other swallow-related biomechanical events and respiratory phase relationships surrounding a swallow, the lung volume at swallow initiation may be an important consideration when investigating swallow physiology and physiopathy.

Multiple rapid swallowing in idiopathic achalasia: evidence for patients’ heterogeneity*

In order to evaluate the function of inhibitory neural pathways in achalasia, we compared the response of the oesophageal body and lower oesophageal sphincter (LOS) to single swallows (SS) and multiple rapid swallowing (MRS) in 20 consecutive patients with untreated idiopathic achalasia (10 men, aged 23-81 years) and in 20 control patients without dysphagia (nine men, aged 31-73 years), using sleeve manometry; 277 SS and 85 MRS were analysed. In the control group, MRS inhibited motor activity in the oesophageal body and induced a slightly lower (P < 0.05) nadir LOS pressure compared with SS. In the achalasia patients, MRS induced a variable response: eight patients had simultaneous motor activity during all MRS although onset was delayed compared with SS [median (interquartile range), 3.5 s (1.7-6.1) vs 1.4 s (0.8-3.9); P < 0.05], whereas eight patients showed motor inhibition which occurred during all MRS in four of them, and the remaining four had no motor activity both after SS and during MRS. Overall MRS did not decrease nadir LOS pressure compared with SS [12 mmHg (5-20) vs 16 mmHg (7-22); P > 0.1]; however, it induced complete LOS relaxation in three of the patients. MRS gives further evidence of functional heterogeneity among achalasia patients.

An optimized13C-urea breath test for the diagnosis ofH pyloriinfection

To validate an optimized (13)C-urea breath test ((13)C-UBT) protocol for the diagnosis of H pylori infection that is cost-efficient and maintains excellent diagnostic accuracy. 70 healthy volunteers were tested with two simplified (13)C-UBT protocols, with test meal (Protocol 2) and without test meal (Protocol 1). Breath samples were collected at 10, 20 and 30 min after ingestion of 50 mg (13)C-urea dissolved in 10 mL of water, taken as a single swallow, followed by 200 mL of water (pH 6.0) and a circular motion around the waistline to homogenize the urea solution. Performance of both protocols was analyzed at various cut-off values. Results were validated against the European protocol. According to the reference protocol, 65.7% individuals were positive for H pylori infection and 34.3% were negative. There were no significant differences in the ability of both protocols to correctly identify positive and negative H pylori individuals. However, only Protocol 1 with no test meal achieved accuracy, sensitivity, specificity, positive and negative predictive values of 100%. The highest values achieved by Protocol 2 were 98.57%, 97.83%, 100%, 100% and 100%, respectively. A 10 min, 50 mg (13)C-UBT with no test meal using a cut-off value of 2-2.5 is a highly accurate test for the diagnosis of H pylori infection at a reduced cost.

An EMG screening method (dysphagia limit) for evaluation of neurogenic dysphagia in childhood above 5 years old

Oropharyngeal dysphagia is not rare in older children before the adult age, especially the patients with cerebral palsy. Non-invasive simple tests are needed for the evaluation of children with neurogenic dysphagia including the patients with cerebral palsy. So we aimed to evaluate non-invasive ways to screen for dysphagia in children and the usefulness of this almost new electrophysiologic method for the detection of dysphagia in children with cerebral palsy. Twenty-eight healthy children and 12 patients with cerebral palsy were investigated for the applicability of this method. The movement of the larynx was monitored using a simple piezoelectric wafer sensor and submental surface EMG activity was recorded by bipolar silver-chloride electrodes taped under the chin over the submental muscle complex. The onset and duration of pharyngeal swallowing was recorded from submental-suprahyoid muscles such as the mylohyoid-genitohyoid-anterior digastric complex. By this method, the maximal water volume capacity was measured in single swallows with progressively increasing water volumes, this was called 'dysphagia limit'. The healthy control children revealed to swallow the bolus at once maximally 11.2+/-0.4 and 2.5 ml in average. Dysphagia limit varied from 7 to above 20 ml water volume from age 5-16 years old. Patients with cerebral palsy had the dysphagia limit of 7.7+/-1.8 and 6.4 ml in average. The dysphagia limit was significantly reduced in patients with cerebral palsy (p<0.05). Dysphagia limit seemed to be less sensitive in demonstrating the oropharyngeal swallowing disorders in childhood period (90% in the adult dysphagic patients). But the majority of patients with cerebral palsy (58%) showed abnormality. This electrophysiologic method is completely non-invasive, devoid from any hazard and applicable to children above 5 years. It may be candidate as a screening test before selection of dysphagic children.

Oynophagia in patients after dental extraction: surface electromyography study.

ObjectivesSurface electromyographic (sEMG) studies were performed on 40 adult patients following extraction of lower third and second molars to research the approach and limitations of sEMG evaluation of their odynophagia complaints.MethodsParameters evaluated during swallowing and drinking include the timing, number of swallows per 100 cc of water, and range (amplitude) of EMG activity of m. masseter, infrahyoid and submental-submandibular group. The above mentioned variables (mean + standard deviation) were measured for the group of dental patients (n = 40) and control group of healthy adults (n = 40).ResultsThe duration of swallows and drinking in all tests showed increase in dental patients' group, in which this tendency is statistically significant. There was no statistically significant difference between male and female adults' duration and amplitude of muscle activity during continuous drinking in both groups (p = 0.05). The mean of electric activity (in μV) of m. masseter was significantly lower in the dental patients' group in comparison with control group. The electric activity of submental-submandimular and infrahyoid muscle groups was the same in both groups.ConclusionSurface EMG of swallowing is a simple and reliable noninvasive method for evaluation of odynophagia/dysphagia complaints following dental extraction with low level of discomfort of the examination. The surface EMG studies prove that dysphagia following dental extraction and molar surgery has oral origin, does not affect pharingeal segment and submental-submandibular muscle group. This type of dysphagia has clear EMG signs: increased duration of single swallow, longer drinking time, low range of electric activity of m. masseter, normal range of activity of submental-submandibular muscle group, and the "dry swalow" aftereffect. The data can be used for evaluation of complaints and symptoms, as well as for comparison purposes in pre- and postoperative stages and in EMG monitoring during treatment of post-surgical oral cavity discomfort and dysphagia.

Surface Electromyography in Preoperative Evaluation and Postoperative Monitoring of Zenker’s Diverticulum

Patients with Zenker's diverticulum (ZD) underwent surface electromyography (sEMG) evaluation to determine sEMG patterns specific for ZD. Group 1 comprised patients with proven long-standing ZD that refused surgical treatment (n = 11, age mean = 55.7 years). Group 2 comprised surgically operated on patients with ZD (n = 6, age mean = 61 years). The timing, amplitude, and graphic patterns of activity of the masseter, submental, and laryngeal strap muscles were examined during voluntary single water swallows ("normal"), single swallows of excessive amounts of water (20 ml, "stress test"), and continuous drinking of 100 cc of water. The muscle activity in pharyngeal and initial esophageal stages of swallowing was measured, and graphic records were evaluated in relation to timing and voltage. The data were compared with the previously established normative database. The main sEMG patterns of ZD are (1) duration of swallowing and drinking is longer than normal (p < 0.05), (2) electric amplitude of laryngeal strap muscles during swallowing activity is higher than normal (p < 0.05), and (3) regurgitation peaks immediately after swallow followed by secondary swallow of the regurgitated portion of a bolus as seen at the sEMG records are specific graphic patterns for the ZD. Zenker's diverticulum has its own specific sEMG patterns. Surface EMG, being an important screening method for patients with dysphagia, is a valuable additional diagnostic tool for ZD. Because it is noninvasive and nonradiographic, it can be used for monitoring of long-standing cases of the disease as well as monitoring of postsurgical recovery.

The influence of tonsillitis on oral and throat muscles in children

Surface electromyography (sEMG) studies were performed on 80 children with acute tonsillitis (AT) and 110 children with recurrent tonsillitis (RT), age 4-12 years, to trace sEMG changes of duration and amplitude of muscle activity during swallowing and continuous drinking. Prospective observational study of randomly chosen patients compared to normative database. Timing and amplitude (in muV) of activity of masseter, submental and infrahyoid muscles were evaluated during voluntary single swallows of saliva ("dry" swallow), water swallows, swallows of excessive amount of water (up to 15 ml), and continuous drinking of 50 ml of water. These parameters were measured for two age groups for both conditions: 4-8 and 9-12 years old. The previously established normative database was taken for control. AT presents prolonged duration of swallowing and electric hyperactivity of infrahyoid muscles but this activity returns to normal after recovery. RT affects masseter and infrahyoid muscles even during periods of remission but do not affect duration of swallowing activity. AT and RT in children age 4-12 years affects muscle activity during swallowing significantly by involving additional muscles (mainly infrahyoid) in this process. AT presents temporary electric hyperactivity of infrahyoid muscles. RT affects masseter and infrahyoid muscles even during periods of remission (pathologic changes are fixed). Abnormally high electric activity of masseter and infrahyoid muscles in patients with RT might serve as an additional indicator for tonsillectomy. Surface EMG of swallowing is a simple, non-invasive and reliable method for diagnostic and preoperative evaluation of dysphagia complaints associated with tonsillitis.

3D volume‐selective turbo spin echo for carotid artery wall imaging with navigator detection of swallowing

To improve 3D volume-selective turbo spin echo (TSE) carotid artery wall imaging by incorporating navigators to reduce artifacts caused by swallowing. Images were acquired on a Siemens Magnetom Sonata 1.5T scanner. 3D volume-selective TSE scans of the carotid arteries were acquired in six healthy volunteers. A cross-pair navigator placed on the back of the tongue was used to detect swallowing and movement. Two swallowing patterns were tested: 1) a single swallow approximately halfway through the scan time, at the center of k(z), and 2) repeated swallowing as often as possible throughout the scan period. Images were acquired with and without navigators for comparison. Signal intensity in the lumen was quantified for the quality of blood suppression, and the clarity of the vessel wall in the common carotid was ranked by four independent blinded observers. In general, lower signal intensity was recorded in the lumen, and decreased blurring and ghosting were observed on scans with navigator control. This reduction in lumen signal intensity signifies an improvement in the black-blood imaging technique. The differences likely reflect the improved double inversion/blood suppression efficiency due to cycles being rejected when the heart rate changed at the point of swallowing, or decreased motional blurring/ghosting of tissue when the navigator is used, or a combination of these two effects. A statistical analysis of image quality showed a significant difference between navigated and non-navigated scans as scored by four independent, blinded observers. For both swallowing patterns, the mean score for the navigator images was on average 0.6 greater than that of non-navigator images (on a scoring scale of 0-5, where 0 = no vessel visible, and 5 = good delineation and blood suppression) and P-values for all observers were less than 0.01. Overall, the central swallow scans were scored higher than the repeated swallow scans. One reason for this may be the fact that the heart rate increased on swallowing, and this often lasted for one or two cardiac cycles after the navigator returned to the normal acceptance position. The effect of the increased heart rate after swallowing is likely to have an effect on double inversion blood suppression efficiency. Therefore, the increased amount of heart rate changes with repeated swallowing may have a greater adverse effect, even if the navigator rejects data views during the swallowing motion. The clarity of vessel wall delineation and the apparent efficiency of blood suppression are reduced by swallowing during acquisition. Both motion blurring and quality of blood suppression are factors that can be improved with the use of a navigator accept/reject method.

Surface electromyographic studies of swallowing in normal children, age 4–12 years

Objectives: Surface electromyographic (sEMG) studies were performed on 100 normal children, age 4–12 years, to establish normative database for duration and amplitude of muscle activity during swallowing and continuous drinking. Study design: Prospective observational study of healthy volunteers. Methods: Parameters evaluated during swallowing include the timing and amplitude (in μV) of activity of m. orbicularis oris, masseter, submental and infrahyoid (laryngeal strap muscles (LSM)) groups covered by platisma. Four tests were examined: voluntary single swallows of saliva (“dry” swallow), voluntary single water swallows as normal, voluntary single swallows of excessive amount of water (up to 15 ml), continuous drinking of 50 ml of water (duration and number of swallows). Duration of muscle activity during swallowing (mean plus standard deviation (S.D.)) was measured for two age groups: 4–8 and 9–12 years old. The group of 40 adults, age 18–30 years, was taken as a control group. Results: Normative data for duration and amplitude of muscle activity during single swallowing and continuous drinking are established for healthy children. The duration of muscle activity during swallows and drinking in all tests showed decrease with the age, and this tendency is statistically significant (one-dimensional analysis of variance, SPSS, χ 2 criterion, 95% confidence interval). There was no statistically significant difference in amplitude (range) measurements between children and adults ( P=0.05). There was no statistically significant difference between male and female children duration of muscle activity during single swallowing and continuous drinking in all age groups ( P≥0.05). Conclusion: Surface EMG of swallowing is a simple and reliable noninvasive method for screening evaluation of swallowing with low level of discomfort of the examination. The normative timing of events data can be used for evaluation of complaints and symptoms, as well as for comparison purposes in pre- and postoperative stages and in electromyography (EMG) monitoring during ENT or neurological treatment. These parameters represent normal deglutition, and can be used to identify abnormalities in pediatric patients, and provide a basis for comparison of swallowing performance, both within and between patients.

Deglutitive inhibition affects both esophageal peristaltic amplitude and shortening.

Deglutitive inhibition attenuates ongoing esophageal contractions if swallows are separated by short time intervals. This study aimed to determine whether esophageal shortening, mediated by longitudinal muscle, was similarly affected. Eight healthy subjects with two distal esophageal segments demarcated by mucosal clips and manometric recording sites positioned within those segments underwent concurrent manometry and fluoroscopy. Peristaltic amplitude and change in distal segment lengths were quantified during single swallows, paired swallows separated by progressively prolonged intervals, and a series of rapid repetitive swallows. During grouped swallows, deglutitive inhibition with complete attenuation of both the manometric contraction and segment shortening was evident with short-interval swallows and rapid-sequence swallows. No inhibition of either was evident with long-interval pairs. With intermediate interswallow intervals, the occurrence and degree of deglutitive inhibition between peristaltic amplitude and segment shortening were closely correlated. Deglutitive inhibition affects both the longitudinal and circular muscle layers of the esophageal wall, and the occurrence of inhibition evident in one layer is strongly correlated with the other.

Dynamics of swallowing-induced cardiac chronotropic responses in healthy subjects.

Simultaneous recording of ECG and swallowing movements in healthy humans (n=23, age 20-57 years) showed that each swallow is accompanied by transient tachycardia with initial abrupt and pronounced heart rate increase. These rapid changes in heart rate (evaluation by maximum increment of heart rate over two successive heartbeats, Delta HR(2bt)) are typical of vagal chronotropic responses. The amplitude of tachycardia induced by a single swallow was significantly higher in the supine position (13.1 +/- 5.6 bpm) compared to the standing position (8.5 +/- 3.8 bpm; p<0.0001). Chronotropic responses to a series of three or more successive swallows consisted of two phases, the initial abrupt acceleration and subsequent slower growth of heart rate. In the standing position, the portion of the first rapid phase significantly decreased, while the portion of the slower phase increased compared to the supine position. The amplitude of tachycardia induced by a single swallow and parameter Delta HR(2bt) can serve as indices of the strength of parasympathetic modulation of the heart. By contrast, further slow increase in the heart rate determined by summation of responses to a series of successive swallows can result from not only inhibition of the parasympathetic influences, but also enhancement of sympathetic activity during swallowing.

Analysis of feeding function and jaw stability in bedridden elderly.

The purpose of this study was to analyze the relationship between jaw stability and the feeding function of 53 bedridden elderly dysphagic patients. Investigations included a questionnaire on daily life activities and meals, oral examinations, functional tests for feeding ability, and assessments of feeding function during the meal. The results of intraoral examination of this patient population for jaw stability revealed that 34.0% of individuals had posterior support for occlusion regardless of whether they had natural teeth or dentures. Thus, the number classified as having mandibular stability (ST) was 18 and that with no mandibular stability (NST) was 35. In a Repetitive Saliva Swallowing Test (RSST), 83.3% of the NST group and 40.0% of the ST group were unable to swallow more than 3 times within 30 seconds. In a water swallowing test, 91.4% of the NST of group was unable to swallow 15 mL of water by a single swallow, while 40.0% of ST group was capable. The results suggest that jaw stabilization by occlusion with the posterior teeth or dental prosthetics is important to feeding function, particularly swallowing.

Swallowing physiology of sequential straw drinking.

The goal of this study was to examine deglutitive physiology during sequential straw drinking in healthy young adults (n = 15) to learn how sequential swallowing differs from single swallows. The physiology of single swallows has been studied extensively in healthy adults and in adults with a variety of debilitating conditions, but the physiology of sequential swallows has not been studied adequately. Videofluoroscopic analysis revealed three distinct patterns of hyolaryngeal complex (HLC) movement during sequential straw swallows: opening of the laryngeal vestibule after each swallow (Type I, 53%), continued vestibule closure after each swallow (Type II, 27%), and interchangeable vestibule opening and closing during the swallow sequence (Mixed, 20%). Unlike discrete swallowing, the onset of the pharyngeal swallow occurred when the bolus was inferior to the valleculae in the majority of subjects and was significantly associated with HLC movement pattern. The leading bolus edge was inferior to the valleculae at swallow onset for Type II movement patterns. For Type I movement patterns, bolus position at swallow onset was randomly distributed between three anatomical positions: superior to the valleculae, at the level of the valleculae, and inferior to the valleculae. Preswallow pharyngeal bolus accumulation, which is common during mastication, was evident and significantly associated with the HLC pattern of opened laryngeal vestibule after each swallow. These data suggest that in healthy young adults, sequential swallows differ physiologically from discrete swallows and indicate substantial variability in deglutitive biomechanics.

A scintigraphic study of oropharyngeal swallowing dynamics in Chagas' disease.

We studied oropharyngeal function in patients with Chagas' disease and oesophageal disease. Twenty-four patients with Chagas' disease, 17 of them with oesophageal disease, were submitted to scintigraphic oropharyngeal transit. A single swallow of a 10-mL bolus of water labelled with 40 MBq 99m Tc-phytate, followed by image acquisition at 20 images s-1 yielded time-activity curves in which oropharyngeal dynamics was evaluated. Thirteen normal volunteers were used as controls. Oral transit was longer for chagasics with oesophageal disease than for controls (P=0.004) or for chagasics with a normal oesophagus (P=0.028). Oesophageal filling rate, measured by the slope of the ascending aspect of the oesophageal radioactivity curve, was lower for chagasics with oesophageal disease than for controls (P=0.037). Also, maximum oesophageal filling rate was lower (P=0. 021) and occurred later (P=0.003) for chagasics with oesophageal disease than for controls. Pharyngeal clearance was positively correlated with oral transit (r=0.603, P=0.002). We conclude that chagasic oesophageal disease is associated with oral transit delay and a slower oesophageal filling rate.

Mechanism of gastroesophageal reflux in premature infants with chronic lung disease

Background/Purpose: The aim of this study was to characterize the motor events responsible for gastroesophageal reflux (GER) and esophageal acid clearance in a cohort of preterm infants with chronic lung disease (CLD). Methods: Esophageal motility was recorded for 2 to 3 hours postprandially in 14 preterm infants with mild-moderate or moderate-severe CLD at 33 to 39 weeks postmenstrual age using a sleeve-side hole micromanometric assembly into which a pH probe had been installed. Results: Twenty-six acid GER episodes were recorded by pH probe. Of these, 22 (85%) were associated with transient lower esophageal sphincter (LES) relaxation. Transient LES relaxations were significantly longer in duration than single swallows (13.7 seconds v 4.6 seconds, P < .001) and had lower nadir pressures (1.1 mm Hg v 2.5 mm Hg, P < .001). During periods of esophageal acidification (pH below 4), peristaltic esophageal body pressure wave sequences cleared acid refluxate more effectively than nonperistaltic pressure wave sequences. Conclusions: In preterm infants with CLD, transient LES relaxations are the predominant mechanism underlying GER, and esophageal clearance mechanisms are fully functional, which is similar to that seen in healthy preterm infants.

Esophageal solid bolus transit: studies using concurrent videofluoroscopy and manometry

OBJECTIVE: Our aim was to assess the efficacy and mechanism of solid bolus transit through the esophagus. METHODS: Eight healthy volunteers were studied with concurrent manometry and videofluoroscopy while swallowing 5 ml liquid barium, a 5–6 mm diameter bread ball, and 4 g chewed bread in both a supine and upright posture. As many as four successive swallows were performed until clearance was achieved. RESULTS: The esophageal clearance of liquid barium was 100% with the first swallow. Clearance of the unchewed bread ball occurred with the first swallow in only 6.7% of trials in the upright posture and 5.9% in the supine posture. After four swallows, clearance was 100% and 52.9% in the upright and supine postures, respectively. Chewed bread was more readily cleared than unchewed bread, with 100% clearance after two swallows in the upright posture and 91% clearance after four swallows in the supine posture. The most common locus of bread stasis was at the aortic arch and carina. The bread boluses were noted to move more effectively when localized in the head as opposed to the tail of the bolus composite. Nonocclusive contractions often occurred at the bolus tail despite the increased peristaltic amplitude seen with the chewed bread. Failed peristalsis, a frequent cause for solid clearance failure, was observed during 30% of all bread swallows. This usually occurred distal to the stopping point of the bolus, suggesting it to be the result rather than the cause of impaired transit. CONCLUSIONS: Although infrequently perceived by these normal subjects and in contradistinction to liquid clearance, bread is rarely cleared from the esophagus with a single swallow. Mastication and an upright posture facilitate the esophageal transport of solids. Bolus composition and impaired bolus transit alter the amplitude and conductance of peristalsis. Manometric data pertaining to liquid clearance through the esophagus do not readily apply to bread.

Esophageal solid bolus transit: studies using concurrent videofluoroscopy and manometry.

Our aim was to assess the efficacy and mechanism of solid bolus transit through the esophagus. Eight healthy volunteers were studied with concurrent manometry and videofluoroscopy while swallowing 5 ml liquid barium, a 5-6 mm diameter bread ball, and 4 g chewed bread in both a supine and upright posture. As many as four successive swallows were performed until clearance was achieved. The esophageal clearance of liquid barium was 100% with the first swallow. Clearance of the unchewed bread ball occurred with the first swallow in only 6.7% of trials in the upright posture and 5.9% in the supine posture. After four swallows, clearance was 100% and 52.9% in the upright and supine postures, respectively. Chewed bread was more readily cleared than unchewed bread, with 100% clearance after two swallows in the upright posture and 91% clearance after four swallows in the supine posture. The most common locus of bread stasis was at the aortic arch and carina. The bread boluses were noted to move more effectively when localized in the head as opposed to the tail of the bolus composite. Nonocclusive contractions often occurred at the bolus tail despite the increased peristaltic amplitude seen with the chewed bread. Failed peristalsis, a frequent cause for solid clearance failure, was observed during 30% of all bread swallows. This usually occurred distal to the stopping point of the bolus, suggesting it to be the result rather than the cause of impaired transit. Although infrequently perceived by these normal subjects and in contradistinction to liquid clearance, bread is rarely cleared from the esophagus with a single swallow. Mastication and an upright posture facilitate the esophageal transport of solids. Bolus composition and impaired bolus transit alter the amplitude and conductance of peristalsis. Manometric data pertaining to liquid clearance through the esophagus do not readily apply to bread.

The 'artificial high pressure zone'. A non-invasive method to study in man the effect of the inhibitory innervation to the oesophagus. Validation study using a combined manometric--barostat technique.

We previously developed a technique to study the effect of inhibitory innervation in the human oesophageal body, by creating an artificial high pressure zone (artificial HPZ) using an intra-oesophageal balloon. Swallowing provokes a fall in pressure in the artificial HPZ that precedes the peristaltic contraction. We aimed to prove that the swallow-induced fall in pressure in the artificial HPZ is due to relaxation of a segmental tonic contraction of the oesophageal wall at that level. Studies were performed in five healthy subjects. Oesophageal pressures were measured at 5, 10 and 15 cm above the lower oesophageal sphincter. A rubber balloon opposite the middle pressure sensor was used to induce the artificial HPZ. A barostat bag was glued to the opposite side of the balloon. The pressure in the barostat bag was pre-set at 8 mmHg below the pressure measured in the artificial HPZ. We studied deglutition-induced variations in the barostat bag volume after single and multiple swallows. Immediately after single swallows and during multiple swallows, we observed a fall in pressure in the artificial HPZ and a significant increase in the barostat bag volume (254+/-67%) from 0.99 (0.37-1.93) to 3.74 (1.91-4.34) (P = 0.005) denoting oesophageal wall relaxation. The swallow-induced fall in pressure in the artificial HPZ represents a real relaxation of a segmental tonic contraction of the oesophageal wall due to deglutitive inhibition. The oesophageal artificial HPZ is a simple method that can be used to study inhibitory phenomena in the body of the human oesophagus.