Combined multichannel intraluminal impedance-pH (MII-pH): multicenter report of normal values from 117 children.

Although combined multichannel intraluminal impedance/esophageal pH monitoring (MII-pH) has replaced prolonged pH monitoring alone for assessing gastroesophageal reflux (GER) in the pediatric population, it does so in the absence of reference values for non-acid GER (NAGER). The purpose of this study was to identify a normal range of NAGER impedance values for infants and children. We evaluated EPM/MII tracings for patients referred for GER assessment to Nationwide Children's Hospital (Columbus, OH), Inova Children's Hospital, and Hospital Italiano (Buenos Aires, Argentina). We excluded tracings from patients who had AGER indices greater than 50 % of the upper end of normal (i.e., >3 % for children >12 months and >6 % for infants ≤ 12 months), had a positive temporal association of GER with symptoms, were on anti-reflux medications at the time of the study, and/or had a fundoplication prior to the study. We also excluded studies with durations shorter than 20 h. Values for NAGER percent time, NAGER episode frequency, frequency of proximal NAGER, and mean NAGER duration were calculated for upright position, recumbent, and total. Study population consisted of 46 infants (20 female [F]/26 male [M], median age 4.8 months [range 3 weeks-11.9 months]) with a median AGER index of 2.2 % (range 0.0-5.9 %) and 71 children (22 F/49 M, median age 7.2 years [range 1.3-17 years]) with a median AGER index of 1.1 % (range 0-3.0 %). Data are presented in tables in the text. The results of this study provide a range of values characteristic of infants and children with normal AGER indices and no positive temporal associations of GER with symptoms. These values may be used as references for comparison to identify infants and/or children who may be at risk of developing serious clinical manifestations due to abnormal patterns of GER.