Effect of swallowed bolus viscosity and body position on esophageal transit, contraction and perception of transit.

BACKGROUND The esophagus has a different response in relation to the characteristics of a swallowed bolus. Bolus viscosity and body position may affect esophageal contraction and transit. Objectives To investigate the effect of bolus viscosity and body position on esophageal contraction, transit and perception. METHODS Esophageal contraction, transit and perception of transit were evaluated in 26 asymptomatic volunteers, 13 men and 13 women aged 18-60 years, mean: 33.6 (12.2) years. Esophageal contraction (manometry) and transit (impedance) were measured with a solid state catheter with sensors located 5, 10, 15, and 20 cm from the lower esophageal sphincter. Each volunteer swallowed in duplicate and in random sequence a 5 mL low viscous (LV) liquid bolus of an isotonic drink with pH 3.3, and a 5 mL high viscous (HV) paste bolus, which was prepared with 7.5 g of instant food thickener diluted in 50 mL of water (pH: 6.4). RESULTS Total bolus transit time, in the sitting position, was longer with the HV bolus than with the LV bolus. Esophageal transit was longer in the supine position than in the sitting position. Bolus head advance time was longer with the HV bolus than with the LV bolus in both positions. Contraction esophageal amplitude was higher in the supine position than in the sitting position. The perception of bolus transit was more frequent with the HV bolus than with the LV bolus, without differences related to position. CONCLUSIONS The viscosity of the swallowed bolus and body position during swallows has an influence on esophageal contractions, transit and perception of transit.