Effect of carbonation and thickening on voluntary swallow in healthy humans.

BACKGROUND: Liquid modification is a widely established strategy of treatment for patients with dysphagia. The modification of liquid particularly by thickening or carbonation is a common approach to promote safe swallowing. OBJECTIVE: This study sought to investigate how carbonated and/or thickened water modulates swallowing behaviours during swallowing in healthy young individuals. METHODS: Thirty-one healthy volunteers (9 men, 22 women; mean age ± standard deviation [SD], 25.7 ± 6.2 years) were instructed to swallow 20 mL of water, carbonated water and carbonated juice with and without added thickening agent. Electromyograms (EMGs) of the suprahyoid (S-hyo) muscles were recorded to evaluate swallowing behaviours. Obtained S-hyo EMG bursts was analysed using the following outcome parameters: onset latency, the time between swallowing que to onset of EMG burst; rising time and falling time, defined as the time between onset and peak, and between peak and offset, respectively; duration, defined as the time between onset and offset of EMG burst; and area integral value under the waveform. RESULTS: Effects of thickening demonstrated the extended onset latency, EMG burst duration including falling time and the larger area of EMG in thickened liquid compared to thin liquid, but there was not much difference between thin and thickened carbonated liquids. Carbonation significantly decreased the duration including falling time for thickened but not for thin liquids. CONCLUSION: Patients with dysphagia can benefit from use of carbonated or thickened water while the effects on swallowing physiology may differ between carbonation and thickening.

Distribution of Recognition Times to Fruity Flavor of Gummy Candies in Healthy Adults.

Times for recognition of fruity flavors in six gummy candies were measured using an electromyography-based system in 23 young healthy participants. They were instructed to chew one of the gummy candies at a random order and to press a button as soon as possible when they recognized what flavor was. The measured 181 recognition times showed two distributions, normally ( n = 107) and non-normally ( n = 74). The overall average of the normal distribution was 7.5 seconds (±2.34 seconds; standard deviation), and there were no differences in the average ratios among the gummy candies. Eighteen of the participants reported 41 inconsistent reports with flavors that were provided by the manufacturer. The most frequently observed report was an apple-flavored gummy candy (14, 34.1%) mainly for a pear-flavored. However, there was no significant correlation between the numbers of recognition times and those of inconsistent flavors among the used gummy candies.

Synchronization of masseter activity patterns between the right and left sides during chewing in healthy young males.

Masseter activity patterns during chewing, which were quantitatively assessed using T50 values, were compared between the right and left sides of healthy young males. Surface electromyograms were recorded from both masseters, and each participant was asked to chew four different agar samples at his own pace across two separate sessions. The four agar samples, each possessing differing textural properties, consisted of two normal and two distinctive agar varieties. The Pearson's correlation coefficient was calculated for each pair of T50 values to evaluate the degree of synchronization of activity patterns between both masseters. A three-way analysis of variance revealed significant main effects of the 'participant' and 'experimental session' factors, but not of the 'test food'. The number of significant coefficients increased stepwise by increasing the number of chews per sequence. These results suggest the importance of the initial stages of chewing sequences in facilitating the synchronization of bilateral masseter activity patterns.

Sequential analysis of masseter activity patterns during chewing in healthy males.

The present study examined sequential changes in masseter activity patterns observed during chewing of four different agar samples in eight healthy young males. Two parameters, T(50) and D(50), were specifically used for evaluation of the activity patterns of individual bursts. Statistical significances were detected in regression coefficients (21.9% of 32 trials) and Spearman's rank correlation coefficients (28.1%) between the calculated T(50) values and chewing cycles, whereas no significant differences among the four agar samples were found. Three (I-III) types of activity patterns of masseter bursts during chewing sequences were classified by the D(50) values, which were derived from the T(50) values. The three types physiologically corresponded to incrementing (Type I), decrementing (Type III) and mixed discharge patterns (Type II). The classification of activity patterns suggested the usefulness of D(50) values in the sequential analysis of masseter activity patterns.