MANOMETRIC EVALUATION OF LOWER ESOPHAGEAL SPHINCTER FUNCTION

The lower esophageal sphincter provides a pressure barrier between the negative intrathoracic and positive intra-abdominal pressure environment. Abnormalities of lower esophageal sphincter function may promote reflux of gastric contents or cause dysphagia, regurgitation, and esophageal dilatation. The function of the sphincter can be best assessed with manometry. The resistance of the lower esophageal sphincter to reflux of gastric juice is determined by the integrated effects of radial pressures exerted over the entire length of the sphincter. Calculation of the sphincter pressure vector volume is superior to standard techniques (i.e., determination of sphincter resting pressure, overall length and abdominal length) in identifying a mechanically defective sphincter as the cause of increased esophageal acid exposure, particularly in patients with subtle sphincter defects. The effect of an antireflux procedure in controlling reflux depends on restoration of the normal sphincter pressure vector volume. Abnormalities of sphincter relaxation documented on manometry are the basis for the diagnosis of achalasia and the hypertensive-hypercontracting lower esophageal sphincter.