Esophageal impedance baselines in infants before and after placebo and proton pump inhibitor therapy.

BACKGROUND Esophageal impedance monitoring records changes in conductivity. During esophageal rest, impedance baseline values may represent mucosal integrity. The aim of this study was to assess the influence of acid suppression on impedance baselines in a placebo-controlled setting. METHODS Impedance recordings from 40 infants (0-6 months) enrolled in randomized placebo-controlled trials of proton pump inhibitor (PPI) were retrospectively analyzed. Infants underwent 24 h pH-impedance monitoring prior to and after 2 weeks of double blind therapy with placebo or a PPI. Typical clinical signs of gastro-esophageal reflux (GER) were recorded and I-GERQ-R questionnaire was completed. KEY RESULTS Median (IQR) impedance baseline increased on PPI treatment (from 1217 (826-1514) to 1903 (1560-2194) Ω, P < 0.001) but not with placebo (from 1445 (1033-1791) to 1650 (1292-1983) Ω, P = 0.13). Baselines before treatment inversely correlate with the number of GER, acid GER, weakly acid GER, acid exposure, and symptoms. The change in baseline on treatment inversely correlates with acid exposure and acid GER. Patients with initial low baselines have no improved symptomatic response to treatment. CONCLUSIONS & INFERENCES Impedance baselines are influenced by GER and increase significantly more with PPI therapy than with placebo. Clinical impact of this observation remains undefined as targeting therapy at infants with low baselines does not improve symptomatic response to treatment.