ACUTE AND CHRONIC INTESTINAL MOTOR-ACTIVITY RESPONSES TO 2 INFANT FORMULAS

Objective. Preterm formulas are nutritionally better for preterm infan ts; however, it has been observed that these formulas cause more feedi ng intolerance than do regular formulas. Because intestinal motor acti vity is responsible for the aboral movement of intraluminal nutrients, the purpose of this study was to evaluate intestinal motor activity r esponses to two infant formulas: 84 and 100.8 J/oz. Study Design and R esults. Intestinal motor activity was recorded in 52 preterm infants w ho had never been fed and who were randomly assigned to receive small enteral feedings (24 mL/kg per day) for 10 days with one of two common ly used infant formulas. In a subset of 26 of these infants, acute mot or responses to both formulas were also evaluated. At the end of the s tudy period, motor activity during fasting did not differ between the two groups of infants. However, motor responses during feeding to the two formulas differed significantly. When infants were fed for the fir st time, their motor activity increased compared with fasting when the y were fed the 84-J/oz formula but decreased when they were fed the 10 0.8-J/oz formula. These differences in motor responses to the two form ulas were not present 10 days later. These differences in motor respon ses to the 100.8- and 84-J/oz formulas were even more pronounced among the 7 infants who subsequently developed feeding intolerance to the 1 00.8-J/oz formula during the 10-day study period. Conclusion, Inhibiti on of motor responses to calorically denser formulas during active fee ding in a subset of preterm infants may underlie the feeding intoleran ce they experience when they are fed these formulas. However, this inh ibitory response diminishes with age, suggesting that denser formulas can be reintroduced later in life to these infants.