Gastroesophageal reflux and respiratory phenomena in infants: Status of the intraluminal impedance technique

Background: The coincidence of recurrent respiratory symptoms and gastroeso phageal reflux (GER) is a well-known phenomenon in infants. Twenty-four-hou r pH metry is the presumed gold standard of diagnostic tools for this sympt om complex, but with this method, only acid (pH <) and alkaline (pH >7) GER can be detected. Gastroesophageal reflux with an esophageal pH in the phys iological range (pH 5-6.8) may represent many cases of clinically relevant GER unrecognized by pH metry. In this study the intraluminal multiple elect rical impedance (IMP) procedure for complete registration of GER was compar ed with pH metry for its diagnostic value in the presence of respiratory sy mptoms. Methods: Twenty-two infants with recurrent regurgitation or pulmonary probl ems were investigated simultaneously with IMP, pH merry, and polygraphy dur ing two feeding periods. Heart rate, oxygen saturation, sleep states, and o ronasal flow were recorded, among other parameters. Results: Three hundred sixty-four occurrences of GER were detected by IMP; only 11.4% had a pH less than 4 and were therefore recognized by pH metry. Three hundred twelve (84.8%) occurrences were associated with breathing abn ormalities, and 11.9% of these were detected by pH metry. Nineteen instance s were accompanied by a decrease of oxygen saturation of more than 10% of t he initial value. Only three (15.8%) of these had a pH less than 4. The rem aining 16 reflux episodes were recognized by IMP only. After software-aided preselection, 165 instances of apnea were visually validated, 49 of which were accompanied by GER. Thirty-eight (77.6%) of these were exclusively rec orded by IMP. Conclusions: The use of pH metry alone cannot detect most GER incidents acc ompanied by respiratory symptoms and therefore does not appear to be suitab le for this approach. The pH-independent IMP technique promises to be a rel iable tool for presumably GER-associated respiratory symptoms.