Is a procedure used to determine whether the esophagus is working properly by measuring the rhythmic muscle contractions(pressures) generated by the esophageal muscles and the sphincter. During the procedure a thin flexible pressure sensitive tube is passed through the nose, down the back of the throat and into the esophagus. Once in the esophagus, the tube will measure the pressures generated by the esophageal muscle when the muscle is at rest and during swallows. This test is used primarily to evaluate the function of sphincter and muscles when there is a presence of reflux, dysphagia or chest pain.