Drug effects on esophageal smooth muscle

To assess which manometric parameters should be evaluated to discriminate health and esophageal motility disorders, we established normal values for lower esophageal sphincter pressure (LESP), LES residual pressure, percentage and duration of LES relaxation, contraction amplitude in the esophageal body, duration of the contractile waves, mode of wave propagation, and shape of contraction amplitudes as well as upper esophageal sphincter pressure (UESP) in 40 healthy volunteers. The values obtained were compared to values in 25 patients with achalasia, 48 patients with nonspecific motility disorders, and 28 patients with reflux esophagitis. Although significant differences of mean values could be found between health and diseased states of esophageal motility, it was impossible to establish clear cutoff points in individuals due to a large overlap of manometric parameters in healthy volunteers and patients. Further prospective studies are necessary to determine sensitivity, specificity, and predictive values of cutoff lines of manometric data. In addition to the inability to define esophageal motility disorders on the basis of motility parameters alone, there is a lack of correlation between the severity of esophageal symptoms and manometric findings. For example, in diffuse esophageal spasm and related disorders, amplitude, duration, configuration, and propagation of esophageal body contractions are not closely related to the severity of symptoms. In reflux esophagitis, mean LESP does not reflect the extent of symptoms or mucosal damage. Only in achalasia, do LESP and resting pressure of the esophageal body seem to be correlated to dysphagia. It is concluded that drug effects on esophageal motility should be evaluated not primarily by manometric data but by clinical effects.