Significant pressure differences between solid-state and water-perfused systems in lower esophageal sphincter measurement.

Objective: High-resolution manometry of the esophagus has gained worldwide acceptance, using different solid-state catheters. Thus, normal values for lower esophageal sphincter (LES) resting pressure in suspected gastroesophageal reflux disease patients have been established using water-perfused manometry. These standard values are commonly applied using also solid-state techniques, although they have never been compared before. The aim of the study was to compare LES measurements obtained with water-perfused manometry with a solid-state technique.
Methods: Thirty healthy subjects were studied twice on the same day: Technique 1: Station pull through using a water-perfused catheter with ports arranged at 0°, 90°, 180° and 270° which were averaged to give a mean LES pressure. Technique 2: Solid-state circumferential probe with a single station pull through. Data were collected using the same computer system and program. The LES pressures were randomly and blindly analyzed.
Results: Twenty-seven subjects out of 30 were analyzed. Using the solid-state system, the mean LES pressure was higher (15.0 vs. 23.3 mmHg, p = 0.003) and 19 of 27 (70%) individual measurements were higher. Two subjects had a hypertensive LES by solid state (58.6 resp. 47.5 mmHg), while their pressures were normal with water-perfused manometry (21.0 resp. 23.4 mmHg). The distal esophageal pressures (mean of pressure at 3 and 8 cm above LES) were the same with the two techniques.
Conclusion: In normal control subjects, LES measurement using circumferential solid-state transducers yields higher pressures than standard water-perfused manometry. Which system yields the "true" resting pressure of the physiologic LES remains to be determined.