Correlation between cardiorespiratory events and gastro-esophageal reflux in preterm and term infants: Analysis of predisposing factors

Background: The association between cardiorespiratory events (CRE) and gastro-esophageal reflux (GER) among neonates is still controversial. Aims: To test such an association in preterm and term infants. Study design: Prospective observational study. Subjects: Forty-seven infants with suspected GER and recurrent CRE admitted at a neonatal intensive care unit, who underwent simultaneous and synchronized 24-hour recording of heart rate (FIR), peripheral oxygen saturation (SpO2) and pH-impedance monitoring (MII-pH). HR/SpO2 data were filtered to avoid artefactual episodes of hypoxia and hypoperfusion. Outcome measures: The main outcome measure was the symptom association probability (SAP), with a 2-minute time window. Infants with positive (> 95%) and negative (<= 95%) SAP index tests were compared by univariate and multivariate statistics. Results: Median gestational age at birth was 29(4/7) weeks, median age at study 36 days. We recorded 3341 GER events and 4936 CRE (4710 desaturations, 226 bradycardias); 609/4936 (12%) CRE were temporally associated with GER episodes: 338 preceded and 271 followed GER events. The SAP index was significant in 5/47 (11%) patients. The SAP index including only CRE following GER events was significant in 3/47 (6%). There was no significant difference in the number of acid, weakly acid, non-acid, pH-only events preceding or following CRE between infants with SAP-positive and SAP-negative tests. Infants with positive SAP-index tests compared to those with SAP-negative tests had lower weight gain in the three days preceding the test and tended to have lower birth weight. Conclusions: GER and CRE were associated in < 11% of patients. The evaluation of ponderal growth might be helpful in predicting such an association.