Effects of bolus consistency and reclining position on kinematic swallowing events in analysis using 320-row area detector computed tomography

This study used 320-row area detector computed tomography (320-ADCT) to determine whether kinematic swallowing events and bolus movement through the oropharynx are affected by bolus consistency and angle of recline. Fourteen healthy adults (4 men, 10 women; age, 22-90 years) underwent 320-ADCT assessment during three 10-mL barium swallow tests, with honey-thick liquid at 60 degrees recline (60 degrees thick), thin liquid at 60 degrees recline (60 degrees thin), and thin liquid at 45 degrees recline (45 degrees thin). The times of swallowing events were measured and compared among the different tests. Bolus propulsion, onset time of true vocal cord (TVC) closure, and upper esophageal sphincter opening were significantly earlier for 60 degrees thin than for 60 degrees thick. Onset time did not significantly differ between 60 degrees thin and 45 degrees thin; however, greater variability was noted for onset of TVC closure with 45 degrees thin, as the TVC started to close before onset of swallowing in 30% of participants. Modulation of TVC closure depends on bolus transport in different reclining positions. The 45 degrees reclining position elicited pre-swallow TVC closure in some participants, which suggests that excessive recline can increase perceived risk of airway invasion during swallowing.