How to Optimally Apply Impedance in the Evaluation of Esophageal Dysmotility.

The utilization of impedance technology has enhanced our understanding and assessment of esophageal dysmotility. Esophageal high-resolution manometry (HRM) catheters incorporated with multiple impedance electrodes help assess esophageal bolus transit, and the combination is termed high-resolution impedance manometry (HRIM). Novel metrics have been developed with HRIM-including esophageal impedance integral ratio, bolus flow time, nadir impedance pressure, and impedance bolus height-that augments the assessment of esophageal bolus transit. Automated impedance-manometry (AIM) analysis has enhanced understanding of the relationship between bolus transit and pressure phenomena. Impedance-based metrics have improved understanding of the dynamics of esophageal bolus transit into four distinct phases, may correlate with symptomatic burden, and can assess the adequacy of therapy for achalasia. An extension of the use of impedance involves impedance planimetry and the functional lumen imaging probe (FLIP), which assesses esophageal biophysical properties and distensibility, and could detect patterns of esophageal contractility not seen on HRM. Impedance technology, therefore, has a significant impact on esophageal function testing in the present day.