Amino Acid-based Formula as a Rescue Strategy in Feeding Very-Low-Birth-Weight Infants With Intrauterine Growth Restriction

Background and Aim: Very-low-birth-weight (VLBW) neonates may develop severe intolerance to standard preterm formula especially if they are associated with intrauterine growth restriction (IUGR). We tested the hypothesis that these infants may tolerate an elemental, amino acid-based formula as a rescue feeding strategy. Methods: In a prospective, case-control pilot study, we enrolled VLBW IUGR infants enterally fed with standard preterm formula (SPF) at daily increments of 16 mL/kg. If gastric residuals accounted for >70% of milk feed in the previous 24 hours, then feedings were temporarily withheld and then resumed with amino acid formula (AAF) increased at the same speed. Cases on AAF were compared to controls on SPF and with cases themselves while on SPF. Primary outcome was the time to reach full enteral feedings. Secondary outcomes were time on parenteral nutrition, time on central venous catheter, and formula tolerability based on the amount of gastric residual volume. Results: Sixty-four infants (22 cases) were enrolled. Although during the total duration of nutrition, cases had worse primary and secondary outcomes, when on AAF, cases were comparable to controls in time to full enteral feeding (14.4 vs 14 days), time on parenteral nutrition, and time on central venous catheter. Cases on AAF and controls had similar gastric residual volumes. At day 3 after AAF introduction, cases had a significantly reduced number (%) of gastric residual volume >5 mL/kg over total number of feedings (5.6 vs 1.5%; P < 0.05) and the mean gastric residual volume (2.7 vs 0.6 mL; P < 0.05) compared to themselves while on SPF. No difference was detected in weight at 21 and 28 days, in main serum parameters and outcome at discharge. Growth at 12 months of corrected age was also comparable. Conclusions: In our population of VLBW IUGR newborns with severe feeding intolerance, a short course on AAF was a safe and effective means of nutritional rescue.