The effect of high- vs low-density barium preparations on the quantitative features of swallowing.

We compared the effect of high-density and low-density barium preparations on the quantitative features of swallowing. The two barium preparations differed primarily in density but also differed somewhat in viscosity. Concurrent videofluoroscopic and manometric studies were done in nine healthy control subjects. Videofluoroscopy was recorded in the lateral projection at 30 frames/sec while concurrent manometry was done with five intraluminal transducers that straddled the pharynx and upper esophageal sphincter. Swallows of 5 and 10 ml of high- and low-density barium preparations were recorded. Analysis indicated that, compared with the low-density barium (1.4 g/cm3), the high-density barium (2.5 g/cm3) preparation had a slower oral and pharyngeal bolus transit time and caused significant quantitative differences in the function of the upper esophageal sphincter. Compared with low-density barium boluses, the high-density barium boluses were associated with later sphincter opening and closure, longer duration of sphincter opening and flow, lower flow rate, greater maximal anterior hyoid movement, greater sagittal sphincter diameter, and higher intrabolus pressure upstream of and within the sphincter. We conclude that the density as well as the viscosity of the barium preparation used in radiologic examination of the oral-pharyngeal phases of swallowing has an influence on bolus transit time through the mouth and pharynx, and on the quantitative features of upper esophageal sphincter opening. Although these quantitative differences cannot generally be recognized visually at fluoroscopy, they become important for the quantitative assessment of swallowing in patients with suspected disorders of oral-pharyngeal swallowing. Therefore, the basic barium preparations used to examine such patients should be either standardized or at least specified.