The Effect of Additives for Reflux or Dysphagia Management on Osmolality in Ready-to-Feed Preterm Formula: Practice Implications.

BACKGROUND: A common osmolality threshold for feedings is to stay <450 mOsm/kg for normal infants. Preterm formulas are frequently modified to improve growth, modify nutrition, and manage gastroesophageal reflux (GER) or dysphagia. Relationships between osmolality and additives to ready-to-feed preterm formulas are unclear. Our aims were to evaluate and compare the effects of caloric density, thickening agent recipes, and supplements to ready-to-feed preterm formula on osmolality.

METHODS: A freezing point osmometer was used to measure the osmolality of 47 preterm infant formula combinations with varying caloric densities (ready-to-feed 22 and 30 cal/oz), thickening agents (rice vs oatmeal cereal), thickener amounts (0.0, 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 tsp/oz), and combinations of supplements (saline, iron, vitamin D, or multivitamin). Ten samples per combination were tested using a 10-μL pipette. Comparisons were made using analysis of variance and t-tests for group and pair-wise comparisons, respectively.

RESULTS: A total of 470 osmolality samples were analyzed: (1) raters had high agreement (r = 0.98; P < .001); (2) for every 0.5 tsp/oz of thickener, the osmolality increases by 30 mOsm/kg (P < .001); (3) osmolality was higher with the oatmeal (vs rice) thickening agent (P < .001); and (4) vitamin and electrolyte supplement combinations increase osmolality.

CONCLUSIONS: Alteration of ready-to-feed preterm formulas may significantly increase osmolality and have unintended consequences. Caution and monitoring should be exercised with modifying ready-to-feed preterm formulas for regurgitation, rumination, GER, dysphagia, feeding intolerance, or emesis. This study supports the concept of achieving volume tolerance before further manipulation of additives.