To correlate lower esophageal (LES) pressure and gastroesophageal (GE) reflux, esophageal manometry and GE scintiscanning have been used to study 40 consecutive patients. Serial scintiscanning was performed as the GE pressure gradient was increased in increments. Reflux was calculated from the ratio of esophageal to gastric radioactivity. The relationship between GE reflux and LES pressure was inverse (r = 0.60, P less than 0.005). Two subgroups of 10 patients were studied further. After atropine, LES pressure decreased from 11.2 +/- 1.1 to 5.3 +/- 0.9 mm Hg (P less than 0.01) at 20 min. The GE reflux index increased from 8.3 +/- 2.1 to 13.4 +/- 2.2% (P less than .05). After bethanechol, LES pressure increased from 8.9 +/- 0.8 to 18.5 +/- 1.0 mm Hg (P less than 0.001) at 30 min. GE reflux decreased from 11.9 +/- 2.4 to 5.8 +/- 1.7% (P less than 0.01).
Conclusions: first, GE reflux correlated with basal LES pressure by an inverse relationship; second, atropine decreased LES pressure and increased reflux; third, bethanechol increased LES pressure and decreased reflux. These data suggest that LES pressure is an important determinant of GE competence.