The role of esophageal pH-impedance testing in clinical practice

Purpose of review: 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. Recent findings: 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. Summary: Esophageal pH-impedance monitoring has potential to augment confidence in a reflux diagnosis beyond that provided by pH-monitoring alone.