Efficacy on gastroesophageal reflux of a thickened formula specifically designed for preterm infants

Background and aims: Gastroesophageal reflux (GER) is common in preterm newborn, due to some promoting factors such the almost fixed lying position, the large fluid enteral intake, the frequent nurse handling and the use of permanent feeding tubes. It may occur with gastrointestinal symptoms (regurgitation, vomiting and feeding intolerance) or with “atypical” symptoms, such as apnoea of prematurity. Twenty-four-hour pH-monitoring, which recognizes GER episodes as a pH drop <4, has traditionally represented the gold standard for GER detection, but is unable to identify non-acid GER episodes. Multichannel intraluminal impedance (MII) is a new technique which detects GER episodes as electrical impedance changes occurring inside esophageal lumen. It can also identify the height reached by each GER episode above the lower esophageal sphincter. Combined pH-MII monitoring allows the detection of both acid and non-acid GER episodes, and thus it can be useful in preterm newborns whose gastric pH is often buffered by frequent milk meals. First-line treatment for GER in preterm infants should be conservative (such as milk thickening and/or body positioning); in fact, recent evidence suggests an association between the use of different drugs which are commonly used in preterm infants and serious adverse effects i.e. ranitidine and necrotizing enterocolitis. Milk thickening has proven to be effective in infants with GER; however, the main limitation of this treatment in preterm newborn is that, at present, commercially-available thickened formula are not adequate to satisfy preterm newborn’s high nutritional needs. The aim of this study is to test the efficacy of an amylopectin-thickened formula specifically designed for preterm infants on acid and non-acid GER by twenty-four hour combined impedance and pH monitoring (pH-MII), which is emerging as the gold standard technique for GER detection in this population. Methods: Twenty-five preterm infants (GA <33 weeks) with symptoms suggestive of GER were studied by 24-hour combined pH-MII monitoring after they had reached full enteral feeding (150 ml/kg/day). During the study period, they received 8 meals: 4 of a standard preterm formula (PF) and 4 of a new preterm formula thickened with amylopectin (TPF). Acid and non-acid GER indexes (number, acidity, duration and height) detected after PF and TPF meals were recorded and compared by Wilcoxon Signed Ranks Test. A p value ≤0.05 was considered statistically significant. Results: All the infants tolerated pH-MII and completed the study period. After TPF meals, total number of GER was lower than the one detected after PF meals [median 45.60 (range, 2–84) vs 55.52 (range, 10–117), p=0.036]. Specifically, after TPF meals a lower number of acid GER detected by pH monitoring was recorded [median 19.12 (range, 1–42) vs 27.60 (range, 0–75) after PF meals, p=0.033]. The number of acid GER detected by MII was similar between TPF and PF [median 6 (range 0–25) vs 6.60 (range, 0–32), p=0.427], as well as the number of non-acid GER [median 20.48 (range, 1–51) vs 21.32 (range, 2–53), p=0.875]. No differences in GER height and duration were found between PF and TPF. Conclusions: Preliminary results of the present study show that a thickened formula specifically designed to satisfy nutritional needs of preterm infants may improve acid GER in this population, but has no effect on non-acid GER. Further data from a larger population are needed to confirm this result.