Acid gastroesophageal reflux reports in infants: a comparison of esophageal pH monitoring and multichannel intraluminal impedance measurements.

Twenty-four-hour tracings generated from combined esophageal pH and multichannel intraluminal impedance measurements of 14 infants (nine males, median age 3.5 months) were examined retrospectively. For each tracing, two acid reflux assessment reports were generated using either pH monitoring alone or pH monitoring combined with impedance. Significantly fewer acid reflux episodes were detected using pH monitoring combined with impedance when compared to pH monitoring alone (25.1+/-4.0 versus 99.9+/-18.3 episodes/patient, p=.001). Estimates of esophageal acid exposure using pH monitoring alone were two-fold higher (137.4+/-23.7 versus 66.6+/-15.9 min/patient, p=.002) than estimates derived using both techniques. Of the total acid reflux episodes detected by pH monitoring alone, 71.8% could not be confirmed by combined pH and impedance. Detection of significant numbers of "pH-only" episodes raises concerns regarding possible over-estimations of acid exposure that may occur when estimates are based solely on esophageal pH monitoring.