Differences in swallowing between high and low concentration taste stimuli.

Taste is a property that is thought to potentially modulate swallowing behavior. Whether such effects depend on taste, intensity remains unclear. This study explored differences in the amplitudes of tongue-palate pressures in swallowing as a function of taste stimulus concentration. Tongue-palate pressures were collected in 80 healthy women, in two age groups (under 40, over 60), stratified by genetic taste status (nontasters, supertasters). Liquids with different taste qualities (sweet, sour, salty, and bitter) were presented in high and low concentrations. General labeled magnitude scale ratings captured perceived taste intensity and liking/disliking of the test liquids. Path analysis explored whether factors of taste, concentration, age group, and/or genetic taste status impacted: (1) perceived intensity; (2) palatability; and (3) swallowing pressures. Higher ratings of perceived intensity were found in supertasters and with higher concentrations, which were more liked/disliked than lower concentrations. Sweet stimuli were more palatable than sour, salty, or bitter stimuli. Higher concentrations elicited stronger tongue-palate pressures independently and in association with intensity ratings. The perceived intensity of a taste stimulus varies as a function of stimulus concentration, taste quality, participant age, and genetic taste status and influences swallowing pressure amplitudes. High-concentration salty and sour stimuli elicit the greatest tongue-palate pressures.

Influence of the perceived taste intensity of chemesthetic stimuli on swallowing parameters given age and genetic taste differences in healthy adult women.

PURPOSE: This study examined whether the perceived taste intensity of liquids with chemesthetic properties influenced lingua-palatal pressures and submental surface electromyography (sEMG) in swallowing, compared with water. METHOD: Swallowing was studied in 80 healthy women, stratified by age group and genetic taste status. General Labeled Magnitude Scale ratings of taste intensity were collected for deionized water; carbonated water; 2.7% w/v citric acid; and diluted ethanol. These stimuli were swallowed, with measurement of tongue-palate pressures and submental sEMG. Path analysis differentiated stimulus, genetic taste status, age, and perceived taste intensity effects on swallowing. Signal amplitude during effortful saliva swallowing served as a covariate representing participant strength. RESULTS: Significant differences (p < .05) in taste intensity were seen across liquids: citric acid > ethanol > carbonated water > water. Supertasters perceived greater taste intensity than did nontasters. Lingua-palatal pressure and sEMG amplitudes were correlated with the strength covariate. Anterior palate pressures and sEMG amplitudes were significantly higher for the citric acid stimulus. Perceived taste intensity was a significant mediator of stimulus differences. CONCLUSION: These data provide confirmatory evidence that high-intensity sour stimuli do influence swallowing behaviors. In addition, taste genetics influence the perception of taste intensity for stimuli with chemesthetic properties, which modulates behavioral responses.

Barium versus nonbarium stimuli: differences in taste intensity, chemesthesis, and swallowing behavior in healthy adult women.

PURPOSE: The authors examined the impact of barium on the perceived taste intensity of 7 different liquid tastant stimuli and the modulatory effect that these differences in perceived taste intensity have on swallowing behaviors. METHOD: Participants were 80 healthy women, stratified by age group (<40; >60) and genetic taste status (supertasters; nontasters). Perceived taste intensity and chemesthetic properties (fizziness; burning-stinging) were rated for 7 tastant solutions (each prepared with and without barium) using the general Labeled Magnitude Scale. Tongue-palate pressures and submental surface electromyography (sEMG) were simultaneously measured during swallowing of these same randomized liquids. Path analysis differentiated the effects of stimulus, genetic taste status, age, barium condition, taste intensity, and an effortful saliva swallow strength covariate on swallowing. RESULTS: Barium stimuli were rated as having reduced taste intensity compared with nonbarium stimuli. Barium also dampened fizziness but did not influence burning-stinging sensation. The amplitudes of tongue-palate pressure or submental sEMG did not differ when swallowing barium versus nonbarium stimuli. CONCLUSIONS: Despite impacting taste intensity, the addition of barium to liquid stimuli does not appear to alter behavioral parameters of swallowing. Barium solutions can be considered to elicit behaviors that are similar to those used with nonbarium liquids outside the assessment situation.

The effect of barium on perceptions of taste intensity and palatability.

Barium may affect the perception of taste intensity and palatability. Such differences are important considerations in the selection of dysphagia assessment strategies and interpretation of results. Eighty healthy women grouped by age (younger, older) and genetic taste status (supertaster, nontaster) rated intensity and palatability for seven tastants prepared in deionized water with and without 40 % w/v barium: noncarbonated and carbonated water, diluted ethanol, and high concentrations of citric acid (sour), sodium chloride (salty), caffeine (bitter), and sucrose (sweet). Mixed-model analyses explored the effects of barium, taster status, and age on perceived taste intensity and acceptability of stimuli. Barium was associated with lower taste intensity ratings for sweet, salty, and bitter tastants, higher taste intensity in carbonated water, and lower palatability in water, sweet, sour, and carbonated water. Older subjects reported lower palatability (all barium samples, sour) and higher taste intensity scores (ethanol, sweet, sour) compared to younger subjects. Supertasters reported higher taste intensity (ethanol, sweet, sour, salty, bitter) and lower palatability (ethanol, salty, bitter) than nontasters. Refusal rates were highest for younger subjects and supertasters, and for barium (regardless of tastant), bitter, and ethanol. Barium suppressed the perceived intensity of some tastes and reduced palatability. These effects are more pronounced in older subjects and supertasters, but younger supertasters are least likely to tolerate trials of barium and strong tastant solutions.

Moving beyond the limitations of the visual analog scale for measuring pain: novel use of the general labeled magnitude scale in a clinical setting.

OBJECTIVE: Quantifying pain intensity is challenging, particularly for patients with chronic pain. The visual analog scale (VAS) is limited by ceiling effects that often leave patients with no ability to quantify worsening pain. The goal of this study was to determine whether the general Labeled Magnitude Scale (gLMS) can be feasibly used to measure pain clinically while overcoming limitations of the VAS. DESIGN: Eighty patients (mean age, 53.7 yrs) scheduled for evaluation of a painful complaint were asked to rate their current pain using the gLMS and the VAS. The time necessary to administer the gLMS was recorded to determine feasibility. The difference in rating between the two scales (VAS and gLMS) was the main outcome measure. RESULTS: After scaling and rounding off the gLMS scores for direct comparison, it was found that the gLMS scores were significantly lower than the corresponding VAS scores by a mean of 1.78 (P < 0.001). The mean time to administer the gLMS was 2.66 mins. CONCLUSIONS: These results suggest that the gLMS has great potential and can be feasibly used to measure pain intensity clinically. The gLMS scores were consistently lower than the VAS scores, thus reducing the ceiling effect and allowing range at the high end of the scale for rating worsening pain.

Effects of chemesthetic stimuli mixtures with barium on swallowing apnea duration.

OBJECTIVES/HYPOTHESIS: This study tested the hypotheses that swallowing apnea duration (SAD) will increase given barium versus water, chemesthetic stimuli (i.e., water < ethanol, acid, and carbonation) mixed with barium, age (older > younger), and genetic taste differences (supertasters > nontasters). STUDY DESIGN: Prospective group design. SETTING: University Medical Center. METHODS: Eighty healthy women were identified as nontasters and supertasters, equally comprising two age groups: 18 to 35 years and 60+ years. The KayPentax Swallowing Signals Lab was used to acquire SAD via nasal cannula during individually randomized swallows of 5 mL barium, 2.7% w/v citric acid with barium, carbonation with barium, and 50:50 diluted ethanol with barium. Data were analyzed using path analysis, with the mediator of chemesthetic perception, adjusted for repeated measures. RESULTS: Significant main effects of age (P = .012) and chemesthetic stimuli (P = .014) were found, as well as a significant interaction between chemesthetic stimuli and age (P = .028). Older women had a significantly longer SAD than younger women. Post hoc analyses revealed that barium mixed with ethanol elicited a significantly longer SAD than other bolus conditions, regardless of age group. There were no significant differences in SAD between barium and water conditions, and no significant effect of chemesthetic perception (P > .05). CONCLUSIONS: Ethanol added to barium elicited longer SAD compared to plain barium, but not the other chemesthetic conditions. Older women had a longer SAD than younger women in all conditions. These findings may influence design of future studies examining effects of various stimuli on SAD.

Main taste effects on swallowing apnea duration in healthy adults.

OBJECTIVE: This study examined swallowing apnea duration (SAD) and respiratory phase patterns as a function of taste, tastes combined with barium, age, and genetic taste group. STUDY DESIGN: Prospective group design. SETTING: University medical center. SUBJECTS AND METHODS: Eighty healthy adult women were identified as nontasters and supertasters and equally comprised 2 age groups: 18 to 35 years (n = 40) and 60+ years (n = 40). The KayPentax Swallowing Signals Lab was used to acquire SAD and respiratory phase patterns via nasal cannula during randomized 5-mL swallows of water, 1.0 M sucrose (sweet), 1.0 M sodium chloride (salty), and 0.032 M caffeine (bitter) alone and mixed with barium. The SAD and respiratory patterns were analyzed in a linear mixed model and a binary logistic regression generalized estimating equation model, respectively. RESULTS: A significant main effect of age was found (P = .007). Older women demonstrated longer SAD than younger women. There were no significant effects of taste or genetic taste group on SAD. There was a significant interaction between barium and supertaster status; SAD was shorter in supertasters when barium was included. There were no significant differences in respiratory patterns between age groups, genetic taste groups, or among taste stimuli. CONCLUSION: Advanced age elicited longer SAD, a robust finding in repeated investigations from multiple laboratories. Main tastes did not affect SAD or respiratory phase patterns. Genetic taste group altered SAD when barium was combined with the taste. That is, taste + barium shortened SAD in supertasters. This finding may affect clinical management of dysphagia patients and warrants further investigation.

The influence of stimulus taste and chemesthesis on tongue movement timing in swallowing.

PURPOSE: To explore the influence of taste and trigeminal irritation (chemesthesis) on durational aspects of tongue movement in liquid swallowing, controlling for the influence of perceived taste intensity. METHOD: Electromagnetic midsagittal articulography was used to trace tongue movements during discrete liquid swallowing with 5 liquids: water, 3 moderate concentration tastants without odor (sweet, sour, sweet-sour), and a high concentration of citric acid (sour taste plus chemesthesis). Participants were 33 healthy adults in 2 gender-balanced, age-stratified groups (under/over 50). Perceived taste intensity was measured using the Generalized Labeled Magnitude Scale (Bartoshuk, 2000; Bartoshuk et al., 2004). Tongue movement sequencing and durations of the composite tongue movement envelope and component events (rise phase, location of first movement peak, release phase) were calculated. RESULTS: No obligate sequence of tongue segment movement was observed. Overall durations and the timing of the first movement peak were significantly longer with water than with the moderate concentration of sweet-sour liquid. Perceived taste intensity did not modulate stimulus effects in a significant way. The expected pattern of shorter movement durations with the high concentration of citric acid was not seen. CONCLUSIONS: A chemesthetic-taste stimulus of high citric acid did not influence the durations of tongue movements compared with those seen during the swallowing of moderate concentration tastants and water.

Effects of chemesthetic stimuli, age, and genetic taste groups on swallowing apnea duration.

OBJECTIVE: This study tested the hypotheses that swallowing apnea duration (SAD) will increase given chemesthetic stimuli (ie, water < ethanol, acid, and carbonation), age (older > young), and genetic taste differences (supertasters > nontasters). STUDY DESIGN: Prospective group design. SETTING: University medical center. SUBJECTS AND METHODS: Eighty healthy adult women were identified as nontasters and supertasters, equally comprising 2 age groups: 18 to 35 years (n = 40) and 60+ years (n = 40). The KayPentax Swallowing Signals Lab was used to acquire SAD via nasal cannula during individually randomized swallows of 5 mL deionized water, 2.7% w/v citric acid, seltzer water, and 50:50 diluted ethanol/water. Data were analyzed using path analysis, with the mediator of chemesthetic perception, adjusted for repeated measures. RESULTS: Significant main effects of chemesthetic stimuli (P = .002), age (P < .001), and genetic taste differences (P = .04) on SAD were found. Older women and supertasters had longer SADs than young women and nontasters. Post hoc analyses revealed ethanol and acid boluses elicited significantly longer SADs than water boluses did. There was no significant effect of chemesthetic perception (P > .05). CONCLUSION: SAD in healthy women increased with changes in chemesthetic stimuli, older age, and in supertasters versus nontasters. It is unclear at this stage if increased SAD is a helpful mechanistic change (potentially protective against aspiration) or a maladaptive change (associated with aspiration). Future research should use these chemesthetic changes in bolus properties to assess if increased SAD decreases aspiration in patients with dysphagia while accounting for genetic taste differences.

Tongue pressure and submental surface electromyography measures during noneffortful and effortful saliva swallows in healthy women.

PURPOSE: The effortful swallow, a compensatory technique frequently employed by speech-language pathologists for their patients with dysphagia, is still not fully understood in terms of how it modifies the swallow. In particular, although age-related changes are known to reduce maximum isometric tongue pressure, it is not known whether age affects people's ability to perform the effortful swallow. In this study, differences were explored between younger and older healthy women in execution of the effortful swallowing maneuver through a comparative analysis of effortful and noneffortful swallows. METHOD: Eighty healthy women (40 age 18-35 years and 40 age 60 and older) participated. Peak amplitude measures and the timing of signal onset to peak were measured using concurrent tongue pressure and submental surface electromyography. Result Statistically significant main effects of age group were not observed in the amplitude data, but older participants showed slower rise times to peak anterior tongue-palate pressure. CONCLUSIONS: Despite the general age-related deterioration of the swallowing musculature due to the phenomenon of sarcopenia, older women can still produce noneffortful and effortful swallows with lingual pressure and submental surface electromyography amplitudes similar to younger women.

Sip-sizing behaviors in natural drinking conditions compared to instructed experimental conditions.

To understand disordered physiology, it is first necessary to determine what constitutes normal function. Liquid sip size during swallowing in healthy individuals has been investigated with varied results. Bolus size is a variable that is manipulated in both research studies and clinical swallowing assessments, so defining normal sip size has relevance in both domains. This study looked at sip size under instruction in experimental tasks and compared it to sip size in free drinking while participants were unaware that drinking was being observed. A statistically significant difference was found in water sip volume between natural drinking (mean = 16 ml) and instructed experimental drinking tasks (mean = 6.6-6.8 ml). This difference far exceeded the magnitude of sip-size variation observed between instructed drinking tasks using different stimuli and as a function of participant's gender or age group.

The effect of taste and palatability on lingual swallowing pressure.

There is evidence that a strong, unpalatable, sour bolus improves swallowing in neurogenic dysphagia. It is not known whether other tastes may alter swallowing physiology. This study investigated the effect of moderate versus high taste concentrations (sweet, sour, salty, bitter) and barium taste samples on lingual swallowing pressure in ten healthy young adults, using a three-bulb lingual pressure array secured to the hard palate. Palatability of the samples was analyzed using the nine-point hedonic scale. Results showed that moderate sucrose, high salt, and high citric acid elicited significantly higher lingual swallowing pressures compared with the pressures generated by water. Pressures in the anterior bulb were significantly higher than those recorded from the middle or posterior bulb. There was no significant effect of palatability on lingual swallowing pressures. High salt and citric acid are known to elicit chemesthesis mediated by the trigeminal nerve. These results suggest that chemesthesis may play a crucial role in swallowing physiology. If true, dysphagia diet recommendations that include trigeminal irritants such as carbonation may be beneficial to individuals with dysphagia. However, before this recommendation more research is needed to examine how food properties and their perception affect swallowing in individuals with and without dysphagia.

Feeding beliefs of certified nurse assistants in the nursing home: a factor influencing practice.

In this study, the author examined the feeding beliefs of 20 certified nurse assistants (CNAs) working in nursing homes using Q methodology and semistructured interviews. Beliefs are defined as a combination of CNA feeding knowledge, experience, and values. Two groups of CNAs with contra belief systems emerged from the analysis. "Social feeders" believe feeding is a time to socialize with residents and "technical feeders" believe prroviding adequate nutrition is the main goal when feeding. CNAs felt their beliefs influenced their feeding practices. Training programs need to include all factors that may influence CNA feeding practices, such as CNAs' beliefs, resident characteristics, and institutional factors.

What do certified nurse assistants actually know about dysphagia and feeding nursing home residents?

The purpose of this study was to examine certified nurse assistants' (CNAs') knowledge of dysphagia and how to feed nursing home residents using nonparticipatory structured feeding observation, critique of staged feeding behaviors on film, and semistructured interview in a triangulation methods design. Content analysis of the data confirmed previous studies that suggested CNAs lack knowledge about dysphagia and how to feed residents. A surprising result was the lack of accurate, comprehensive information in CNA texts and classrooms about dysphagia and how to manage challenging feeding behaviors. Speech-language pathologists are uniquely trained to improve CNA communication skills and provide accurate information to nursing colleagues. Specific recommendations of how to improve CNA feeding training programs are provided.

Effect of citric acid and citric acid-sucrose mixtures on swallowing in neurogenic oropharyngeal dysphagia.

The ability of sour and sweet-sour mixtures to improve swallowing in 11 nursing home residents with neurogenic oropharyngeal dysphagia was investigated using fiberoptic endoscopic evaluation of swallowing. Citric acid (2.7%) significantly reduced aspiration and penetration compared with water. Teaspoon delivery of liquids significantly reduced aspiration and penetration compared with natural cup drinking. Subjects tended to appropriately self-regulate the cup volume they consumed after the first trial. A significant increase in spontaneous dry swallows was observed after both taste stimuli. The mechanisms for improved swallowing due to citric acid are not understood but may be due to increased gustatory and trigeminal stimulation of acid to the brainstem in neurologically impaired subjects.