Reevaluation of the balloon in gastrointestinal manometry.

Although the flow-through catheter (FTC) system has been useful and satisfactorily accurate for gastrointestinal manometry, we hypothesized that a cylindrical, liquid-filled balloon would also accurately reflect stress imposed by a sphincter. Latex balloons were fitted over the side ports of a closed-end catheter. The responses of the balloon and FTC system were compared in a cylindrical chamber commonly identified as a Starling resistor. Independent, constant-pressure sources were used to control both the inwardly directed "contact pressure" of the Starling resistor (Ps) and the intraluminal fluid pressure (P(lum)). The balloon transducers responded linearly and accurately (slope = 1) to changes in both Ps and P(lum) within the test range (0-200 mmHg, 0-26.7 kPa). When either P(lum) or Ps was held constant and the other changed, the balloon transducers always accurately measured the higher of the two pressures. Although the performance of the FTC system was improved after the Starling resistor was lubricated, the FTC system sometimes responded inaccurately to changes in Ps. The ability of the balloon transducers to measure the contractions of the lower esophageal sphincter and of the esophagus was demonstrated. We conclude that the balloon transducer can measure sphincter pressure accurately and suggest that, in certain circumstances, it might be advantageous relative to the FTC system.