Noninvasive Evaluation of the Biomechanical Accommodations to Bolus Volume during Human Swallowing

Abstract

Bolus volume is very important in the biomechanics of swallowing. By noninvasively characterizing swallow responses to volume challenges, we can gain more knowledge on swallowing and evaluate swallowing behavior easily. This study aimed to evaluate the impact of bolus volume on the biomechanical characteristics of oropharyngeal swallowing events with a noninvasive sensing system. Fifteen healthy male subjects were recruited and instructed to swallow 5, 10, and 15 ml of water. The sensing system consisted of a tongue pressure sensor sheet, bend sensor, surface electrodes, and a microphone. They were used to monitor tongue pressure, hyoid activity, surface EMG of swallowing-related muscles, and swallowing sound, respectively. In addition to the onset, the peak time and offset of the above four structures, certain characteristics, such as the duration, peak value, and interval of the structure motions, were measured during the different drinking tasks. The coordination between the hyoid movement and tongue pressure was also assessed. Although no sequence of the structural events changed with volume, most of the timings of the structural events were significantly delayed, except for certain hyoid activities. The swallowing volume did not affect the active durations of the monitored structures, the peak values, or intervals of tongue pressure and supra- and infrahyoid muscle activity, but certain hyoid kinetic phases were prolonged when a larger volume was swallowed. Additionally, sequential coordination between hyoid movement and tongue pressure was confirmed among the three volumes. These findings suggest that oropharyngeal structural movements change in response to bolus volume to facilitate safe swallowing. The noninvasive and quantitative measurements taken with the sensing system provide essential information for understanding normal oropharyngeal swallowing.

A review on intelligent aid diagnosis for dysphagia using swallowing sounds

“…Considering the swallowing motion trajectory and its anatomic location variations, some studies have acquired swallowing signals at the suprasternal notch 24,25 . However, the majority of signal acquisitions utilized sensors positioned around the cricoid cartilage of the neck [26][27][28][29][30][31][32][33][34][35][36] . Takahashi et al 37 conducted the first comprehensive study of collection sites and found that the optimal detection site (site 1) was located at the lower edge of the cricoid cartilage, bilaterally in the trachea.…”

“…Beyond individual differences, several studies have examined the effect of swallowing tasks on swallowing sounds. Li et al 33 compared acoustic differences in swallowing sounds across different volumes of bolus. Youmans and Steirwalt 36 reported on the characteristics of duration, intensity, and frequency associated with swallowing sounds at different concentrations of nudges.…”