Effect of bolus volume on the response of the human esophagus to a viscous bolus.

It is well known that increasing the volume of a non-viscous bolus has no significant effect on esophageal peristalsis. Viscous boluses, however, tend to remain more compact during passage through the esophagus; we therefore sought to determine whether increasing the volume of a viscous bolus would significantly affect esophageal peristalsis. Intraluminal pressure events were measured with a low-compliance-infused catheter system, and lower esophageal sphincter (LES) pressure was monitored continuously with a Dent sleeve. Each subject was given a series of 10 swallows of a water bolus (viscosity, 0.89 centipoise) and of a viscous bolus (syrup; viscosity, 102 centipoise). The volume of each bolus varied (5, 10, 15, 20 ml), and the order of administration of each set of swallows was randomized. Tracings were coded and analyzed blindly. Increasing the volume of the non-viscous bolus had no significant effects of esophageal peristalsis. Additionally, the viscous bolus at each volume was associated with significant (p less than 0.05) reductions in peristaltic wave velocity and significant (p less than 0.05) increments in durations of contraction and LES relaxation. However, increasing the volume of the viscous bolus did not significantly alter variables of esophageal peristalsis. It is concluded that altering the volume of a viscous bolus has no incremental effect on esophageal peristalsis over the effect of viscosity alone.