Current concepts of esophageal function.

Current state of the art methods for esophageal manometry may be performed with either a nonperfused probe with intraluminal transducers or a perfused catheter system. The perfusate should be driven by a low compliance pump through catheters 0.8 mm. in diameter. The upper esophageal sphincter pressure profile is asymmetrical, with higher pressures in the anterior and posterior directions than laterally. The lower esophageal sphincter pressures are higher in the left and left posterior directions. There is symmetry of peristaltic pressures in the body of the esophagus. The discussion of the physiology of swallowing includes the "on" response and the "off" and "duration" response. The lower esophageal sphincter is normally in a state of constant contraction and is relaxed following stimulation of the vagus nerve. The mechanisms of the control of the lower esophageal sphincter remain to be fully demonstrated.