Esophageal Impedance: Role in the Evaluation of Esophageal Motility

AbstractThe esophagus is a hollow muscular tube with ends closed proximally and distally by muscular sphincters. The upper esophageal sphincter and proximal one third of the esophageal body are composed of striated muscle. There is then a transition zone where striated and smooth muscle mix together. The lower esophageal sphincter and the distal one half to two thirds of the esophageal body are composed of smooth muscle. Esophageal peristalsis results from sequential contraction of circular muscles, which serves to push the ingested food bolus toward the stomach with minimal stasis in the esophageal body. Therefore, esophageal motility testing aims to investigate esophageal function and to reveal any disorders to explain individual symptoms and provide a rationale for treatment. In 1991, impedance monitoring was introduced by Jiri Silny as a new technique to detect the flow of certain physical properties through hollow viscera, which later inspired numerous studies in which the possible applications of this technique were investigated. When combined with manometry, impedance provides information on esophageal bolus transit while manometry provides information on esophageal contractile activity. Subsequently, normal values for combined impedance and manometry have been reported with different methodologies worldwide, and such technique allows the acquisition of more information than manometry alone in patients with esophageal motility abnormalities. Therefore, combined impedance and manometry is emerging as an important tool for understanding and obtaining detailed information about the physiology and pathophysiology relevant to esophageal motility. Other potential clinical implications of this technique may include the functional classification of esophageal motor disturbances in patients with non-obstructive dysphagia, and the perioperative management of laparoscopic fundoplication which could impact esophageal motility. In this review, the clinical applications of this emerging new technique are summarized with regard to the technical aspects of this technology. The advantages they offer over conventional techniques for the evaluation of esophageal motor diseases are reported