Influence of Body Height on Oral and Pharyngeal Transit Time of a Liquid Bolus in Healthy Volunteers.

Background: Swallowing duration may be influenced by several factors. The effect of body height on oral-pharyngeal bolus transit has not been clearly elucidated. The hypothesis of this investigation was that height has influence on oral-pharyngeal transit time of a liquid bolus.

Methods: Videofluoroscopic assessment of swallowing was performed on 40 healthy volunteers: 20 "tall" (171 cm to 207 cm) and 20 "short" (152 cm to 170 cm) subjects, 10 men and 10 women in each group. Each subject performed three swallows of 10 mL of liquid barium bolus. The following parameters were measured: oral transit time (OTT): time from the beginning of tongue tip movement at incisors to arrival of the bolus tail at the fauces; pharyngeal transit time (PTT): time between the arrival of the bolus tail at fauces and complete passage of the bolus tail through the upper esophageal sphincter (UES); pharyngeal clearance (PC): time between the arrival of the bolus head at fauces to complete passage of the bolus tail through the UES; UES opening (UESO): time between the arrival of the bolus head at the UES to complete passage of the bolus tail through the UES; duration of hyoid movement (HM): time interval between the onset and the end of hyoid movement; oral-pharyngeal transit time (OPTT): time from the beginning of tongue tip movement at incisors until complete passage of the bolus tail through the UES. The statistical analysis was done by a linear model with mixed effects. Correlation between height and swallowing events duration was assessed by Spearman's correlation coefficient (r).

Results: In women OTT, PC, HM and OPTT were longer in tall than in short subjects, what was not seen in men. In women there was a positive correlation between OTT, PTT and OPTT and height. Men (mean height: 177 cm) had longer PTT and PC than women (mean height: 166 cm).

Conclusions: In women, oral and pharyngeal transit time of a 10 mL liquid bolus were influenced by height and was longer in taller subjects.