Comprehensive Assessment of Reflux Burden and Mucosal Integrity in Children: Insights from MNBI and Impedance–pH Monitoring

TL;DR

The study finds that MNBI helps identify acid reflux in children, with different patterns in infants versus older kids.

Contribution

The study introduces age-specific MNBI thresholds for diagnosing GERD in children, improving diagnostic accuracy.

Findings

MNBI correlates inversely with acid exposure in children ≥1 year old, indicating mucosal impairment.

Infants show more weakly acidic and liquid reflux, while older children have more gas reflux.

MNBI performs better in older children with optimal cut-offs at ~2525 Ω (Z6) and 3079 Ω (Z5).

Abstract

What are the main findings?

Mean nocturnal baseline impedance (MNBI) correlates inversely with acid exposure and effectively identifies esophageal mucosal impairment in children with GERD, particularly in those ≥1 year old.

Distinct age-related reflux patterns were observed: infants exhibited more weakly acidic and liquid reflux episodes, while older children showed a predominance of gas reflux.

What is the implication of the main finding?

MNBI provides an objective, reproducible marker that complements standard pH-impedance metrics and improves diagnostic accuracy in pediatric GERD.

Age-specific MNBI thresholds are needed to optimize diagnosis and guide management, as adult cut-offs are not directly applicable to children.

Background: Pediatric gastroesophageal reflux disease (GERD) presents with heterogeneous phenotypes across ages, and diagnostic challenges persist. Multichannel intraluminal impedance and pH (MII-pH) monitoring is the current gold standard, while mean nocturnal baseline impedance (MNBI) has emerged as a marker of mucosal integrity in adults. Pediatric normative data are still lacking. We aim to characterize age-related reflux patterns and assess the association between MNBI and pathological acid exposure in children undergoing MII-pH monitoring. Methods: We retrospectively analyzed 226 children evaluated with 24 h MII-pH monitoring between 2017 and 2025. Clinical and laboratory data were reviewed. Children were stratified by age (<1 year vs. ≥1 year). Pathological reflux was defined as reflux index (RI) > 10% in infants and >7% in older children. MNBI was measured at distal channels (Z5, Z6) during nocturnal recumbency. Correlations between MNBI and RI were assessed. Diagnostic performance of MNBI for pathological acid exposure was evaluated using ROC analysis. Results: Infants had more total reflux episodes, particularly weakly acidic and liquid, whereas older children exhibited more gas reflux. MNBI correlated inversely with RI (Z6 r = −0.337; Z5 r = −0.281; both p < 0.0001). In infants, MNBI poorly discriminated pathological acid exposure. In older children, MNBI showed better performance, with optimal cut-offs of ~2525 Ω (Z6) and 3079 Ω (Z5) yielding specificities > 85%. Conclusions: MNBI is a reproducible, age-sensitive marker of reflux burden in children, best suited for older children where it complements RI in diagnosing acid-mediated GERD. Larger prospective studies are needed to establish pediatric reference values.

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