Differentiation of esophageal pH-impedance characteristics classified by the mucosal integrity marker in human neonates.

BACKGROUND: In adults, distal baseline impedance (BI) is a determinant of esophageal mucosal integrity with values <900 Ω indicating inflammation. Relationships between acid gastroesophageal reflux (GER) and BI in neonates are unclear. METHODS: NICU infants (N = 198, 30.4 ± 0.3 weeks gestation) were evaluated at 43 ± 0.4 weeks postmenstrual age using 24-h pH-impedance. Ten randomly selected 1-min windows during rest from the distal impedance channel (Z6) were averaged. Chi-square, t-tests, and ANOVA were used to compare pH-impedance and symptom characteristics by BI severity (BI < 900 Ω, BI 900-2000 Ω, BI > 2000 Ω). Regression analysis was used to identify potential contributing factors of BI. RESULTS: In BI < 900 Ω: (1) pH-impedance characteristics were increased (acid reflux event frequency, duration, and severity, all P < 0.05 vs. BI > 2000 Ω), and (2) positive symptom correlations were noted with bolus (73%) and acid events (55%). Significant predictors of BI included chronological age, acid reflux index, and BPD diagnosis (all P < 0.05). CONCLUSIONS: Low BI is associated with prolonged acid exposure, delayed clearance, and greater aerodigestive symptom prevalence, likely associated with inflammation and or increased mucosal permeability. BI > 2000 Ω likely involves little or no inflammation because acid exposure is minimal. Combination of SAP, pH-impedance metrics, and BI along with the clarification of dysmotility mechanisms provides the rationale for personalized anti-reflux therapies as needed.