A Relation Between the Piezoelectric Pulse Transducer Waveforms and Food Bolus Passage during Pharyngeal Phase of Swallow

Purpose: Since a Piezoelectric Pulse Transducer (PPT) detects finger peripheral pulse-waves, the PPT has already been used to simply record the laryngeal upward-downward movements. However, a relation between the sensor output and movements of the pharynx, larynx, and esophagus was not clear. This study was aimed to elucidate a relation between the PPT waveforms and food bolus passage during the pharyngeal phase of swallow. Methods: The laryngeal movements by the PPT, surface electromyography of the geniohyoideus muscle, and videofluorography were simultaneously recorded. To synchronize VF, the PPT waveforms, and EMG, we touched the neck surface lightly using a small metal ball both before and after swallowing, thereby putting marks on the VF and the waves of the PPT. Then, features in the waveform of the PPT were analyzed with a personal computer. Results: The swallowed food bolus was stopped for a moment on the epiglottic vallecula, as observed by VF. This stop was also observed in the PPT waveform as a return to the baseline. The epiglottis returned to the original position at the end of swallowing, as can be observed by VF and by a small peak in the PPT waveform. The food bolus passage was divided into two periods on the PPT waveform: TA (transit period from the base of the tongue to the epiglottic vallecula), and TB (transit period from the epiglottic vallecula to the esophagus). Conclusion: The PPT waveforms could detect bolus passage from the base of the tongue through the epiglottic vallecula to the esophagus.