The influence of bolus volume on oropharygeal swallowing in healthy subjects

Abstract

Objective To observe the effects of bolus volume on pharyngeal and upper esophageal sphincter pressures and durations in healthy volunteers by using high-resolution manometry (HRM).Methods Twentyfour health subjects were recruited and asked to swallow three volumes of bolus (3 ml,5 ml and 10 ml) in the neutral head position.Pressure and duration measurements were acquired by utilizing a high-resolution solid-state manometer,with an emphasis on the hypopharynx and upper esophageal sphincter (UES).Variables including UES residual pressure,UES relaxation duration,maximum hypopharygeal pressure and hypopharyngeal pressure duration were analyzed across bolus volumes and consistencies by using three-way repeated measures analysis of variance (ANOVA) to investigate influence of bolus volume.Results UES residual pressure [-1.71 mmHg(3 ml thick liquid)vs.-4.68 mmHg(10 ml thick liquid)],UES relaxation duration[590.45 ms(3 ml thick liquid) vs.702.49 ms (10 ml thick liquid)],maximum hypopharygeal pressure [169.91 mmHg (3 ml thick liquid) vs.204.42 mmHg (10 ml thick liquid)] and hypopharyngeal pressure duration(P ＜0.05) varied significantly across bolus volumes when swallowing water or thick liquid.The UES relaxation duration,UES residual pressure and maximum hypopharyngeal pressure had a direct positive relationship with bolus volume.There was significant differences with regard to UES relaxation duration [685.75 ms(3 ml paste)vs.772.27 ms (10 ml paste)] but not to UES residual pressure (P ＞ 0.05) and maximum hypopharyngeal pressure (P ＞ 0.05) across bolus volume when swallowing paste.Conclusions Difference in hypopharyngeal pressure and duration,UES residual pressure and duration were detected across varying bolus volumes.Consideration of these variables is paramount in understanding normal and pathological swallowing. Key words: Bolus volume; Deglutition; Swallowing physiology; High-resolution manometry