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To examine the characteristics and changes in the pharyngeal phase of swallowing according to fluid viscosity in normal healthy persons, to help determine fluid intake methods in more detail than the use of standardized fluid.
This was a prospective observational study involving 10 normal healthy adults. While the participants sequentially took in fluids with 10 different viscosities changes in the pharyngeal phase of the swallowing process were monitored using videofluoroscopic swallowing studies (VFSS). Twenty parameters of the pharyngeal phase, including epiglottis contact, laryngeal elevation, pharyngeal constriction, and upper esophageal sphincter opening, were determined and compared.
No significant viscosity-based changes in epiglottis contact, laryngeal elevation, or upper esophageal sphincter-opening duration of the pharyngeal phase were observed. However, pharyngeal transit time and time from the start of the pharyngeal phase to peak pharyngeal constriction were significantly delayed upon intake of fluid with viscosities of 150.0 centipoise (cP) and 200.0 cP.
VFSS analysis of fluid intake may require the use of fluids of various concentrations to determine a suitable viscosity of thickener mixture for each subject.
Citations
To compare fluid thickeners composed of starch polysaccharide (STA), guar gum-based polysaccharide (GUA), and xanthan gum-based polysaccharide (XAN) with the use of a viscometer and a line spread test (LST) under various measurement conditions.
The viscosity of thickened fluid with various concentrations (range, GUA 1%-4%, XAN 1%-6%, STA 1%-7%, at intervals of 1%) was measured with a rotational viscometer with various shear rates (1.29 s-1, 5.16 s-1, 51.6 s-1, and 103 s-1) at a temperature of 35℃, representing body temperature. The viscosity of STA showed time dependent alteration. So STA was excluded. Viscosities of GUA and XAN (range of concentration, GUA 1%-3%, XAN 1%-6%, at intervals of 1%) were measured at a room temperature of 20℃. LST was conducted to compare GUA and XAN (concentration, 1.5%, 2.0%, and 3.0%) at temperatures of 20℃ and 35℃.
The viscosities of 1% GUA and XAN were similar. However, viscosity differences between GUA and XAN were gradually larger as concentration increased. The shear thinning effect, the inverse relationship between the viscosity and the shear rate, was more predominant in XAN than in GUA. The results of LST were not substantially different from GUA and XAN, in spite of the difference in viscosity. However manufacturers' instructions do not demonstrate the rheological properties of thickeners.
The viscosities of thickened fluid were different when the measurement conditions changed. Any single measurement might not be sufficient to determine comparable viscosity with different thickeners. Clinical decision for the use of a specific thickener seems to necessitate cautious consideration of results from a viscometer, LST, and an expert's opinion.
Citations
To evaluate the effects of physical properties of foods on the changes of viscosity and mass as well as the particle size distribution after mastication.
Twenty subjects with no masticatory disorders were recruited. Six grams of four solid foods of different textures (banana, tofu, cooked-rice, cookie) were provided, and the viscosity and mass after 10, 20, and 30 cycles of mastication and just before swallowing were measured. The physical properties of foods, such as hardness, cohesiveness, and adhesiveness, were measured with a texture analyzer. Wet sieving and laser diffraction were used to determine the distribution of food particle size.
When we measured the physical characteristics of foods, the cookie was the hardest food, and the banana exhibited marked adhesiveness. Tofu and cooked-rice exhibited a highly cohesive nature. As the number of mastication cycles increased, the masses of all foods were significantly increased (p<0.05), and the viscosity was significantly decreased in the case of banana, tofu, and cooked-rice (p<0.05). The mass and viscosity of all foods were significantly different between the foods after mastication (p<0.05). Analyzing the distribution of the particle size, that of the bolus was different between foods. However, the curves representing the particle size distribution for each food were superimposable for most subjects.
The viscosity and particle size distribution of the bolus were different between solid foods that have different physical properties. Based on this result, the mastication process and food bolus formation were affected by the physical properties of the food.
Citations
Method: We retrospectively reviewed the videofluoroscopic findings of 83 dysphagia patients with various underlying conditions. We used 2 cc of diluted barium as thin viscosity food, 2 cc of yoplait as medium viscosity food, and 2 cc of semiblended gruel diet as thick viscosity food. We assessed the presence of aspiration and the amount of residue in valleculae and pyriform sinus with 3 grade scales.
Results: Aspiration was more frequently observed in thin viscosity (32.5%) than medium (6.0%) or thick viscosity (8.4%) (p＜0.05). Vallecular residue was more abundant in thick viscosity than medium, and in medium viscosity than thin (p＜0.05). Pyriform sinus residue was more abundant in thick viscosity than thin viscosity (p＜0.05).
Conclusion: We conclude that thickened food may make more pharyngeal residue after swallow in dysphagia patients with weak pharyngeal constriction. Therefore the texture, another property of food, needs to be further studied. (J Korean Acad Rehab Med 2003; 27: 186-191)
Objective: The objective of this study is to assess whether the patients with dysphagia, who must take fluid thickener and dysphagia diet, have adequate fluid and calory intake.
Method: Fifteen patients with dysphagia were participated in this study. In all of them, dysphagia was documented by videofluoroscopy and viscosity modification was recommended. The amount of fluid and calory intake was measured for 3 consecutive days during taking thickened fluid and dysphagia diet. serum sodium, blood urea nitrogen (BUN) and creatinine (Cr) level were measured.
Results: Fourteen of 15 patients with dysphagia took adequate fluid and calory. In thirteen of 14 patients, BUN/Cr ratio and serum sodium were within normal limit. In one of 14 patients, BUN/Cr ratio was elevated due to excessive protein intake. One of 15 patients with dysphagia took the fluid and calory under the standard. Her BUN/Cr ratio was 27.2. But this patient took more fluid and nutrition day after day. At 3rd day after measurement, she took adequate fluid and calory.
Conclusion: Sufficient fluid and calory could be supplied with fluid thickener and dysphagia diet. But physician should observe carefully whether dysphagic patient consume adequate amount of fluid and calory. (J Korean Acad Rehab Med 2002; 26: 249-253)
Objective: The videofluoroscopic swallowing study (VFSS) has been accepted for standard method of dysphagia evaluations. But there is no research for oropharyngeal effects depending on the change of viscosity.
Method: The 10 normal subjects without dysphagia symptom or history were participated. 4 test foods were selected according to viscosity which was measured by line spread test (LST); thick semiblended diet: LST 1 cm, Yoplait: LST 2.44 cm, tomato juice: LST 3.67 cm, 35% diluted barium: LST 4.15 cm. Each foods were swallowed 3 times during VFSS. We measured oral transit time (OTT), pharyngeal delay time (PDT), pharyngeal transit time (PTT), and cricopharyngeal opening time (CPOT)
Results: There was linear correlation between OTT and LST (cm)(r=0.965, P＜0.05). As the score of LST increased, PDT tended to increase linearly, but there was no statistical significance (r=0.949, P=0.509). PTT and CPOT had no significant correlation with viscosity.
Conclusion: The viscosity affected OTT and PDT. The test foods of VFSS and dysphagia diet shoud be selected by viscosity measures.
The oropharyngeal swallow of 26 patients with dysphagia was studied quantitatively and qualitatively using videofluoroscope. Videofluoroscopic examination was done with head in neutral position, and with three different consistency of test meals; thin liquid, thick liquid, and solid. When aspiration or laryngeal penetration was noted in neutral position, the study was repeated with different head positions. We compared them with each other and with 25 normal subject(previously presented).
11/26(42%) patients revealed laryngeal penetration or aspiration at least with one consistency of test meal. Aspiration occurred more frequently in thin liquid than thick liquid or solid. Head position change successfully eliminated aspiration in 10/10 patient(100%). Other one patient could not change his head position.
9 numerical parameters were derived and calculated for quantitative examination. Liquid meal oral discharge time, pharyngeal delay time, and pharyngeal transit time were significantly increased in patients with aspiration than in patients without aspiration. Also significantly increased than those of normal controls.
Because different test meal consistency gave different values, direct comparison of values regardless of meal consistency was fruitless. And because all the process of swallowing cannot be expressed as numerical parameters, qualitative examination of videofluoroscopic result was essential.
In conclusion, liquid meal oral discharge time, pharyngeal delay time, and pharyngeal transit time were useful parameters in differentiating and quantifying dysphagia. Aspiration can be reduced when appropriate position assumed. Calculated values were different according to the consistency of the test meal. Quantitative analysis was helpful, but qualitative examination of videofluoroscopy was essential.
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