Quantification of Resistance to Flow at the Esophagogastric Junction in Man

Changes in resistance to flow at the esophagogastric junction contribute to the regulation of esophageal emptying and gastroesophageal reflux. To quantify esophagogastric resistance in man we have adapted our pneumatic resistometer, previously validated in the dog. The system is based on the measurement of nitrogen flow through a 5‐cm‐long polyurethane cylinder placed within the gut lumen and maintained electronically at a constant pressure gradient. In vitro experiments showed that the amplitude, length, and diameter of the constricted segment each contribute to resistance as measured by our instrument. In vivo studies performed on eight healthy volunteers showed that the esophagogastric junction was the place of maximal resistance in the gastroesophageal region. Intragastric resistance was also comparatively high whereas esophageal body resistance was negligible. Esophagogastric junction resistance was similar for antegrade and retrograde flow. During swallowing, it decreased to 10% of resting values. In three patients with achalasia, it was markedly increased and did not vary significantly during swallowing. We conclude that pneumatic resistometry accurately quantitates segmental resistance to flow in the esophagogastric region. Under normal conditions esophagogastric junction resistance exceeds gastric resistance and, hence, provides a gradient against gastroesophageal reflux. However, this resistance gradient between the junction and the stomach is much narrower than previously thought on the basis of manometric measurements. Copyright © 1990, Wiley Blackwell. All rights reserved