Pharyngeal pressure analysis by the finite element method during liquid bolus swallow

The human pharynx is unique, acting as a complex interchange between the or al cavity and the esophagus, and between the nasal cavity and the lungs. It is actively involved in the transport of food and liquid, producing the fo rces that guide the bolus into the upper esophagus and away from the adjace nt larynx and lungs. This study developed a biomechanical computer model of the human pharynx, utilizing a finite element method (FEM). Control 2-dime nsional cine computed tomography images were obtained during 10-mL barium p aste swallows at 8 levels extending from the tongue base to the cricopharyn geal level in order to encompass the entire pharynx. Three-dimensional fini te element models of the pharynx were reconstructed from the geometric info rmation obtained From the images at each level. Using an inverse dynamic ap proach with the addition of known tissue properties, we analyzed the 8 mode ls under estimated pressure histories during swallow. Within each model, ch anges in the cross-sectional intraluminal area were calculated and compared with the area from the computer-generated FEM model. Area matching allowed estimation of intraluminal pressure gradients during swallow. The estimate d pressure gradients were distributed through a range from 10 to 55 mm Hg, varying from one region to another and showing different patterns for the u pper 4 levels and the lower 4 levels. The contraction velocity for the uppe r 4 levels was much higher than that for the lower 4 levels. The higher con traction velocities and pressure gradients in the upper levels are consiste nt with the bolus velocities required for efficient swallow.