Experimental evaluation of an endoscopic balloon for manometry of esophageal varices

Measurement of pressure in esophageal varices may be performed using an endoscopic balloon technique. Improvements in this technique are described, and a complete experimental assessment of its potentials and limitations using an in vitro model consisting of an artificial esophagus containing a water-filled tube (varix) is reported. The influence of the varix diameter (3, 5, and 7 mm) and wall thickness (0.031, 0.144, and 0.256 mm) and the possible effect of the elasticity or peristalsis of the esophageal wall were investigated. Four hundred eighty pressure measurements were performed between 5 and 40 cm H₂O. Linear regression analysis showed a good correlation between the pressure in the varix and that measured endoscopically (r > 0.9). No obvious measurement bias was found for any of the varices. Variability in pressure measurement was low in all thin-walled varices, and only in a 3-mm thick-walled varix was it found to be high [lower limit, -11.2 (1.4) cmH₂O; upper limit, 6.4 (1.4) cm H₂O]. Pressure measurement in a 7-mm varix was not affected by simulated peristalsis or esophageal wall elasticity. Intraobserver and interobserver reliability of measurement assessed in a series of 324 pressure measurements by three endoscopists was excellent. The authors conclude that this method may give reliable results in large and medium-sized varices and may be unaffected by peristalsis or esophageal wall elasticity. However, further assessment in vivo remains necessary.