Bolus aggregation in the oropharynx does not depend on gravity

Area of Science:

• Deglutition science
• Biomechanics of swallowing
• Oropharyngeal physiology

Background:

• The role of gravity in bolus transport and aggregation within the oropharynx before swallowing is not fully understood.
• Understanding the mechanics of bolus transit is crucial for diagnosing and managing swallowing disorders.

Purpose of the Study:

• To investigate whether gravity influences bolus aggregation in the oropharynx prior to the initiation of a swallow.
• To elucidate the primary drivers of food transport from the oral cavity to the pharynx.

Main Methods:

• A before-during study design was employed with five healthy adult volunteers.
• Videofluorography captured the swallowing process of soft and hard barium-containing foods in upright and quadruped (kneeling face down) positions.
• Key outcome measures included oral cavity food processing duration, vallecular bolus aggregation, and pharyngeal swallow timing.

Main Results:

• Oropharyngeal transport of chewed solid food (stage II transport) commenced seconds before the pharyngeal swallow, irrespective of posture or food consistency.
• Bolus aggregation in the valleculae occurred on average 1.7 ± 2.5 seconds before the pharyngeal swallow (p < .001).
• Tongue-palate contact was identified as the primary mechanism driving stage II transport.

Conclusions:

• Oropharyngeal food transport is an active process, propelled by tongue-palate contact, and is independent of gravitational forces.
• Bolus accumulation in the valleculae can occur for several seconds preceding a swallow, independent of body position.