The role of esophageal pH-impedance testing in clinical practice

Ambulatory reflux monitoring is typically performed when esophageal symptoms do not respond to usual antireflux medications, or prior to invasive antireflux therapy. Although pH-based metrics have been the standard in defining esophageal reflux burden, novel impedance parameters have been introduced in recent years that can either be extracted from pH-impedance monitoring or obtained directly from esophageal mucosa. This review evaluates the clinical role of esophageal pH-impedance monitoring in clinical practice in the present day.

Elevated acid exposure time in the distal esophagus remains the primary metric that predicts symptom improvement from antireflux therapy. Although conventional impedance-based metrics (numbers of reflux episodes, reflux-symptom association) provide complementary evidence, novel impedance-based metrics show promise in documenting reflux-induced damage to esophageal mucosal integrity, and in potentially predicting treatment outcome. The postreflux swallow-induced peristaltic wave measures integrity of primary peristalsis triggered by a reflux episode. Baseline impedance values reflect histopathological damage to mucosal integrity, and improve following successful antireflux therapy. Mucosal impedance assessed at endoscopy is a new diagnostic tool that is currently being evaluated in multinational research studies.

Esophageal pH-impedance monitoring has potential to augment confidence in a reflux diagnosis beyond that provided by pH-monitoring alone.