Oral, pharyngeal, and esophageal transit of an acidic bolus in healthy subjects

The swallowing function is influenced by chemical and sensory stimuli. The aim of this investigation was to evaluate the effect of an acidic sour bolus on its oral, pharyngeal, and esophageal transit in healthy volunteers.

Scintigraphic evaluation of the transit was performed in 43 healthy subjects aged 23–71 years. Each subject swallowed, in a random sequence, 5 mL of two liquid boluses: acidic (50 mL of water with 3 g of concentrated lemon juice, pH 3.0) and neutral (water, pH 6.8), both labeled with 37 MBq of technetium-99m phytate. A series of images of each swallow were acquired at 20 frames/s for 20 s with the subjects sitting in front of the collimator of the gamma camera.

There was no difference between neutral and acidic boluses in terms of their transit and clearance durations and in the amount of residues when passing through the mouth and pharynx. In the proximal esophagus, the transit and clearance were longer with the neutral bolus (clearance 1.40 ± 0.11 s) than with the acidic bolus (1.17 ± 0.07 s, p = 0.04). In the distal esophagus, the transit and clearance were longer with the acidic bolus (clearance 10.66 ± 0.87 s) than with the neutral bolus (6.60 ± 0.58 s, p = 0.01). The amount of residues in the middle and distal esophagus was greater with the acidic bolus. There was no correlation between distal esophageal clearance duration and the amount of residues with the neutral bolus, but there was a positive correlation with the acidic bolus.

An acidic bolus causes slower bolus transit in the distal esophageal body as compared to a neutral bolus.