Stef Jj

Effect of increased intraabdominal pressure on lower esophageal sphincter pressure

This study evaluates the effect of intraabdominal pressure increases on lower esophageal sphincter (LES) pressure in normal subjects and in patients with reflux esophagitis. Intraabdominal and intragastric pressure were increased by abdominal compression, the Valsalva maneuver, and leg raising. In normal subjects changes in pressure recorded from the LES equaled the changes in gastric pressure induced by abdominal compression and Valsalva. Consequently the LES-gastric pressure gradient remained unchanged. During leg raising, pressure recorded from the LES increased more than gastric pressure, thereby increasing the LES-gastric pressure gradient. Although statistically significant, the LES pressure increases associated with leg raising were modest, unrelated to initial sphincler pressure, and unaffected by atropine. When individuals demonstrating a “common cavity” phenomenon were excluded, LES pressure changes during abdominal compression were similar in patients with esophagitis and in normal volunteers. Consequently, response of the LES to abdominal compression generally does not separate patients with esophagitis from normal subjects. We believe that the LES responses to increased intra-abdominal pressure observed in this study are better accounted for by mechanical factors than by a physiologic adaptive response of intrinsic LES tone.

Relationship between serum gastrin concentration and lower-esophageal sphincter pressure

Serum gastrin concentration [G] has been proposed as the major factor regulating resting lower-esophageal sphincter pressure (LESP). Available supporting evidence in man, however, is largely circumstantial. The present study directly compares measurements of LESP with concurrent levels of circulating serum gastrin in fasting human subjects. A direct correlation was not shown betwen [G] and resting LESP; rather, a trend existed toward an inverse relationship. The study results indicate that the concentration of serum immunoreactive gastrin is not a major determinant of lower-esophageal sphincter tone in humans.