Effect of viscosity on oropharyngeal and esophageal emptying in man

Effects of Food and Liquid Properties on Swallowing Physiology and Function in Adults

Foods and liquids have properties that are often modified as part of clinical dysphagia management to promote safe and efficient swallowing. However, recent studies have questioned whether this practice is supported by the evidence. To address this, a scoping review was conducted to answer the question: "Can properties of food and liquids modify swallowing physiology and function in adults?" Online search in six databases yielded a set of 4235 non-duplicate articles. Using COVIDENCE software, two independent reviewers screened the articles by title and abstract, and 229 full-text articles were selected for full-text review. One-hundred eleven studies met the inclusion criteria for qualitative synthesis and assessment of risk of bias. Three randomized controlled trials and 108 non-randomized studies were analyzed. Large amounts of variability in instrumental assessment, properties of food and liquids, and swallowing measures were found across studies. Sour, sweet, and salty taste, odor, carbonation, capsaicin, viscosity, hardness, adhesiveness, and cohesiveness were reported to modify the oral and pharyngeal phase of swallowing in both healthy participants and patients with dysphagia. Main swallow measures modified by properties of food and liquids were penetration/aspiration, oral transit time, lingual pressures, submental muscle contraction, oral and pharyngeal residue, hyoid and laryngeal movement, pharyngeal and upper esophageal sphincter pressures, and total swallow duration. The evidence pooled in this review supports the clinical practice of food texture and liquid consistency modification in the management of dysphagia with the caveat that all clinical endeavors must be undertaken with a clear rationale and patient-specific evidence that modifying food or liquid benefits swallow safety and efficiency while maintaining quality of life.

In-house-Prepared Semisolid Bolus for Esophageal Transit Scintigraphy in Normal Volunteers and its Comparison with Liquid Bolus

Background/Aims:

Esophageal transit scintigraphy (ETS) is a useful tool for evaluating esophageal motility disorders, although conflicting results are seen due to lack of ideal bolus. Semisolid/solid boluses have shown superiority over liquid boluses, and the present study aims to establish the utility of in-house-prepared bolus in normal volunteers and its comparison with liquid bolus.

Materials and Methods:

Thirty-three healthy volunteers were selected for ETS with in-house-prepared semisolid bolus jelly containing ^99mTc-sulfur colloid. Dynamic studies were acquired in anterior projection with single swallow for both supine and sitting positions. T90% esophageal emptying time (EET) was calculated for whole and three equally divided segments of esophagus and also done with liquid bolus on different day.

Results:

The median value of EET for semisolid bolus for whole esophagus in sitting and supine positions was 11.7 s (interquartile range [IQR]: 8.0–16.7) and 17.7 s (IQR: 12.0–33.0). EET of liquid bolus for whole esophagus in sitting and supine positions was 9.3 s (IQR: 8.0–13.3) and 13.0 s (IQR: 9.7–25.0), respectively. Significantly different EET for whole esophagus and lower one-third esophagus between sitting and supine positions was seen for semisolid (whole esophagus;P = 0.003, lower one-third esophagus; P = 0.025) and liquid boluses (whole esophagus; P = 0.032, lower one-third esophagus; P = 0.016). Comparing EET using semisolid and liquid boluses, only lower one-third esophagus in supine position showed significant difference (P = 0.033).

Conclusions:

In-house-prepared semisolid radiolabeled jelly is inexpensive, easy to prepare with good radiolabeling. Condensed dynamic images from semisolid bolus were better, sharper, and reproducible in comparison to liquid bolus without fragmentation. This study standardized semisolid bolus and verified its suitability for clinical use.

Viscosity of food boluses affects the axial force in the esophagus

AIM: To study the effect of viscosity on axial force in the esophagus during primary peristalsis using a newly validated impedance-based axial force recording technique.

METHODS: A probe able to simultaneously measure both axial force and manometry was positioned above the lower esophageal sphincter. Potable tap water and three thickened fluids were used to create boluses of different viscosities. Water has a viscosity of 1 mPa·s. The three thickened fluids were made with different concentrations of Clinutren Instant thickener. The viscous fluids were in appearance comparable to pudding (2 kPa·s), yogurt (6 kPa·s) and slush ice (10 kPa·s). Six healthy volunteers swallowed 5 and 10 mL of boluses multiple times.

RESULTS: The pressure amplitude did not increase with the bolus viscosity nor with the bolus volume whereas the axial force increased marginally with bolus volume (0.1 > P > 0.05). Both techniques showed that contraction duration increased with bolus viscosity (P < 0.01). Association was found between axial force and pressure but the association became weaker with increasing viscosity. The pressure amplitude did not increase with the viscosity or bolus volume whereas the axial force increased marginally with the bolus size.

CONCLUSION: This indicates a discrepancy between the physiological functions that can be recorded with axial force measurements and pressure measurements.

Oesophageal bolus transit and clearance by secondary peristalsis in normal individuals

BACKGROUND

Secondary peristalsis is important for the clearance of retained refluxate or material from the oesophagus. Combined impedance and manometry can directly detect both oesophageal contraction and bolus transit.

AIM

To apply combined impedance and manometry to characterize oesophageal bolus transit and clearance by secondary peristalsis in healthy individuals.

METHODS

Eleven healthy volunteers underwent combined impedance and manometry with a catheter containing seven impedance-measuring segments and eight water-perfusion pressure transducers. Saline and solid agar boluses of 5 ml were applied for primary peristalsis and secondary peristalsis was stimulated by rapid mid-oesophageal injections of saline.

RESULTS

The rate for complete bolus clearance of secondary peristalsis with saline injections was less than that of primary peristalsis with saline swallows (69 vs. 95%, P=0.02). No statistical difference in bolus propagation time between primary and secondary peristalsis was observed (P=0.45). Bolus presence time of secondary peristalsis was significantly longer than that of primary peristalsis for all impedance-measuring segments (all P<0.05). Solid swallows differed from saline swallows with lower rate of complete bolus transit and longer bolus transit time.

CONCLUSION

Our data show that the impedance technique can successfully characterize oesophageal bolus transit and clearance by secondary peristalsis. These findings suggest that secondary peristalsis may be less effective than primary peristalsis regarding oesophageal transit and clearance of a liquid bolus.

Assessment of Swallowing Sounds by Digital Cervical Auscultation in Children

Objectives:

There is a lack of studies regarding swallowing sounds in children 3 to 11 years of age. This study aimed to assess swallowing sounds by digital cervical auscultation in children of this age group without symptoms of oropharyngeal dysphagia.

Methods:

Digital cervical auscultation was performed in 118 subjects by use of a piezoelectric microphone. The children swallowed 5 mL of liquid and yogurt. The components of perceptual acoustic analysis were discrete initial signal (DIS), main signal of swallowing sound (MS), discrete final signal (DFS), and expiratory return (ER). Duration in seconds was the objective parameter of the swallowing sound signal analyzed.

Results:

Fifty-six boys and 62 girls were evaluated at a mean (±SD) age of 6.9 ± 2.03 years. A complete DIS-MS-DFS-ER swallowing sequence was found in 60% of the children. There was no significant difference in swallowing sound duration between both food consistencies (p = .189) or between genders either for liquid (p = .327) or yogurt (p = .792). There was no correlation between age and duration of the swallowing sound for liquid or yogurt.

Conclusions:

We concluded that digital cervical auscultation was able to provide objective information about the swallowing process that could contribute to methodological standardization in children.

Evaluation of a Solid Bolus Suitable for Esophageal Scintigraphy

This study was designed to select a suitable solid bolus for esophageal scintigraphy. Optimally, a bolus should leave minimal residual buccal and pharyngeal activity after being swallowed. We compared the oropharyngeal behavior of three boluses, i.e., omelette, egg white, and paté of 1- and 3-ml volume. Thirty patients without dysfunction of the upper esophageal sphincter were recruited for the study. Scintigraphy interpretation was based on the results of condensed images and time activity curves. A total of 108 oropharyngeal transits were analyzed. First we determined the most appropriate volume (1 or 3 ml) of paté, omelette, and egg white (i.e., the volume with the least residual oropharyngeal activity). Buccal or pharyngeal bolus retention occurred significantly less frequently with 1 ml paté than 3 ml (p = 0.03) and also less frequently with 3 ml egg white than with 1 ml egg white (p = 0.03), and the mean buccal bolus retention index was lower using 3 ml omelette than 1 ml omelette (p = 0.03). Then we identified the most suitable of the three selected boluses. Both oral and pharyngeal residues were higher for paté (1 ml) than for omelette (p = 0.02 and 0.05), and pharyngeal residue was significantly lower for omelette (3 ml) than for egg white (3 ml) (p = 0.02). In conclusion, a 3-ml bolus of radiolabeled omelette seems to be the most suitable bolus for exploration of esophageal transit, and its use could enhance the potential of scintigraphy in the assessment of esophageal disorders.

Categorization of dysphagia diets with the line spread test11No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit on the author(s) or on any organization with which the author(s) is/are associated

OBJECTIVE

To categorize dysphagic diets according to the food's viscosity, as determined by an objective method.

DESIGN

Description of dysphagic diet in terms of viscosity.

SETTING

Food science laboratory at a university hospital.

SPECIMENS

Twenty kinds of foods: 10 commercially available and 10 formulated for a dysphagic diet in a tertiary university hospital, representing a wide range of food viscosities.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Viscosity, measured with a viscometer, and a line spread test (LST).

RESULTS

Logarithmic viscosity (centiPoise [cP]) values measured using a viscometer were inversely correlated with the extent of spread (centimeters) on an LST. (Pearson r=-.95, P=.0001). Viscosities and the LST results were 0.9+/-0.1cP and 5.5+/-0.5cm for water, 63.1+/-4.8cP and 3.4+/-0.1cm for the barium solution, 671.0+/-76.9cP and 2.4+/-0.1cm for yogurt, and 10,031+/-728cP and 1cm for pudding.

CONCLUSIONS

Dysphagic diets can be categorized according to their viscosities by objective measurements. The LST correlated well with viscometer measurement and is a practical method with which to measure viscosity.

Oropharyngeal Scintigraphy: A Reliable Technique for the Quantitative Evaluation of Oral–Pharyngeal Swallowing

A valid and reliable technique to quantify the efficiency of the oral-pharyngeal phase of swallowing is needed to measure objectively the severity of dysphagia and longitudinal changes in swallowing in response to intervention. The objective of this study was to develop and validate a scintigraphic technique to quantify the efficiency of bolus clearance during the oral-pharyngeal swallow and assess its diagnostic accuracy. To accomplish this, postswallow oral and pharyngeal counts of residual for technetium-labeled 5- and 10-ml water boluses and regional transit times were measured in 3 separate healthy control groups and in a group of patients with proven oral-pharyngeal dysphagia. Repeat measures were obtained in one group of aged (> 55yr) controls to establish test-retest reliability. Scintigraphic transit measures were validated by comparison with radiographic temporal measures. Scintigraphic measures in those with proven dysphagia were compared with radiographic classification of oral vs. pharyngeal dysfunction to establish their diagnostic accuracy. We found that oral ( p = 0.04), but not pharyngeal, isotope clearance is swallowed bolus-dependently. Scintigraphic transit times do not differ from times derived radiographically. All scintigraphic measures have extremely good test-retest reliability. The mean difference between test and retest for oral residual was -1% (95% CI -3%-1%) and for pharyngeal residual it was -2% (95% CI -5%-1%). Scintigraphic transit times have very poor diagnostic accuracy for regional dysfunction. Abnormal oral and pharyngeal residuals have positive predictive values of 100% and 92%, respectively, for regional dysfunction. We conclude that oral-pharyngeal scintigraphic clearance is highly reliable, bolus volume-dependent, and has a high predictive value for regional dysfunction. It may prove useful in assessment of dysphagia severity and longitudinal change.

Accommodation to changes in bolus viscosity in normal deglutition: a videofluoroscopic study

Videofluoroscopic swallow studies were performed on 60 normal adult volunteers. Swallowing variables were measured during swallows of a 3-cm3 paste bolus and a 3-mL liquid bolus and were compared to identify changes in swallow gesture displacement and timing, as well as changes in bolus movement timing. The study revealed that some differences measured by videofluoroscopy appear to be the result of the inherent bolus characteristics, while others likely represent changes in swallow gestures needed to accommodate variations in bolus viscosity. The overall timing of pharyngeal transit did not vary between bolus types. Oropharyngeal transit trended toward being faster for a liquid bolus with a concurrent early elevation of the aryepiglottic folds. The hyoid bone elevated at the same time, at the same rate, and to the same extent irrespective of bolus viscosity. During a liquid bolus swallow, the hyoid bone trended toward a more prolonged elevation, corresponding to prolonged pharyngoesophageal sphincter opening. The pharyngoesophageal sphincter, however, opened to a greater extent with a paste bolus.

Does the supplementation of the formula with fibre increase the risk of gastro-oesophageal reflux during enteral nutrition? A human study

BACKGROUND & AIMS

Fibre-supplements in enteral feeding could increase the risk of gastro-oesophageal reflux (GOR). The aim of this study was to assess in humans the physiological effects of the supplementation of the enteral diet with different types of dietary fibre on gastro-oesophageal reflux episodes, gastric acidity and gastric emptying.

METHODS

pH profiles were compared in 12 healthy volunteers between three different formula (500 kcal, 250 mL x h-1) delivered in a random order and containing either no fibre, either soy polysaccharide fibre only or mixed fibre from pea and inuline. Enteral diets were instilled through a nasogastric tube. Oesophageal and gastric pH recordings were combined with the ultrasound measurement of gastric antral area during the infusion.

RESULTS

More GOR were observed with a fibre-free diet (median 4, range 1-10) than with a mixed (median 1.5, range 0-5) (P=0.04) or soy polysaccharide fibre (median 1.5, range 0-5) (P=0.04) diet. The median duration of GOR was longer with the mixed fibre (median 3.6, range 1.8-7.2) than with the fibre-free diet (mean 1.8 min, range 1-3.6) (P<0.05). The number of GOR episodes lasting more than 5 min, the duration of the longest GOR and the percent of time under pH 4 were not significantly different with the three diets. The intragastric pH profile and the ultrasound antral area were not different with all three diets.

CONCLUSIONS

Addition of fibre to the enteral formula had limited effects on the onset of GOR episodes. It decreased the number of GOR but increased their duration. These effect were more pronounced with the formula containing soluble fibre. At variance, the addition of fibre had no significant effect on gastric emptying and gastric acid secretion.

Dysphagia after antireflux surgery

BACKGROUND

Dysphagia is experienced by many patients after antireflux surgery. This literature review examines factors associated with the development, prediction and management of postoperative dysphagia.

METHODS

Published studies examining issues related to dysphagia, gastro-oesophageal reflux and fundoplication were reviewed.

RESULTS

Postoperative dysphagia is usually temporary but proves troublesome for 5--10 per cent of patients. Technical modifications, such as a partial wrap, division of short gastric vessels and method of hiatal closure, have not conclusively reduced its incidence. There is no reliable preoperative test to predict dysphagia.

CONCLUSION

It is uncertain whether postoperative dysphagia arises from patient predilection or is largely a consequence of mechanical changes created by fundoplication. Anatomical errors account for a significant proportion of patients referred for correction of dysphagia but these are uncommon in large single-institution studies. Abnormal manometry cannot predict dysphagia and, on current evidence, 'tailoring' the operation does not prevent its occurrence.

Esophageal function testing using multichannel intraluminal impedance

Multichannel intraluminal impedance (MII) is a new technique for evaluation of bolus transport. We evaluated esophageal function using bolus transport time (BTT) and contraction wave velocity (CWV) of liquid, semisolid, and solid boluses. Ten healthy subjects underwent MII swallow evaluation with various boluses of sterile water (pH 5), applesauce, three different sized marshmallows, and iced and 130 degrees F water. The effect of bethanechol was also studied. There was no difference in BTT or CWV for all water volumes from 1 to 20 ml. There was significant linear increase of BTT with progressively larger volumes of applesauce, and BTT of applesauce was longer than for water. BTT was significantly longer with large marshmallows vs. small and medium and was longer than for water. BTT for iced water was similar to 130 degrees F water. Applesauce showed a significant linear decrease of CWV with progressively larger volumes and was slower than water. Marshmallow showed significantly slower CWV with the large vs. small, and CWV for ice water was significantly slower than 130 degrees F water. Therefore, BTT of liquid is constant, whereas BTT of semisolid and solid are volume dependent and longer than liquids. CWV of semisolids and solids are slower than liquids. CWV of cold liquids is slower than warm liquids. MII can be used as a discriminating test of esophageal function.

Double-blind placebo-controlled study of cisapride in patients with nonspecific esophageal motility disorder accompanied by delayed esophageal transit

BACKGROUND

Nonspecific esophageal motility disorder (NEMD) represents a difficult therapeutic challenge because of the heterogeneous nature of the esophageal motor functions. We studied the effects of cisapride on the esophageal symptoms and esophageal motor function in a group of patients with NEMD showing delayed esophageal transit.

METHODS

Seventy eligible patients were entered into a 4-week, double-blind randomized comparison of 10 mg of cisapride or placebo, four times daily. Symptom assessment, esophageal manometry after wet swallows, and esophageal scintigraphy after intake of a liquid and solid bolus were performed in each patient before and after treatment.

RESULTS

After 4 weeks of treatment cisapride significantly increased the prevalence of esophageal peristaltic contractions (percentage of total contractions, P < 0.05 versus base line and placebo) and significantly improved esophageal emptying of the solid bolus (P < 0.05 versus placebo) but not of the liquid bolus. Placebo did not have any significant effects versus base line on these variables. Both placebo and cisapride improved the distal esophageal amplitude versus base line (no significant intergroup differences). Symptom scores were significantly reduced after 4 weeks of treatment versus base line in both groups (no significant intergroup differences except for heartburn and regurgitation, P < 0.05). On global evaluation of treatment, significantly more patients in the cisapride group were rated as markedly or moderately improved, when compared with placebo.

CONCLUSIONS

The results of the present study showed that cisapride is effective and well tolerated in patients with NEMD accompanied by delayed esophageal transit. Symptomatic improvement may possibly be related to its beneficial action on the esophageal body by increasing the number of peristaltic contractions and esophageal emptying of solids.

Esophageal transit scintigraphy

Esophageal transit scintigraphy was introduced over 20 years ago, but its exact role in the evaluation of patients with suspected esophageal motility disorders still remains controversial. The experience with this test supplies clues, if not answers, for the following key questions: "When is it useful?", "How should it be performed?", and "Are there different methods for different applications?" Opinions vary, but it seems at the very least to be useful clinically under the following conditions: (1) when esophageal manometry is unavailable or not tolerated, (2) when manometry is equivocal or negative but a reasonable suspicion of disease remains, and (3) when clinical management will be aided by monitoring for serial change or response to therapy.