Gastric Emptying Time in Preterm Infents: Comparison between Breast Milk and Formula Milk

ABSTRACT

PURPOSE: Failure of adequate gastric emptying frequently interferes with successful enteral nutrition in infants. Study of gastric emptying in preterm infants has been hampered by the absence of a suitable and, valid technique, but ultrasonic assessment is well tolerated by infants. The aim of this study is to compare gastric emptying rates of breast milk and formula within preterm infants using an ultrasonic technique. METHODS: Ten infants(6 males, 4 females) were studied on 20 occasions. Median gestation of the group was 33 wks(29-38 wks), birthweight was 1506gms(850-1870gms). Each infant was receiving a minimum of 150 ml/kg/day of breast milk. We conducted the study with breast milk first and with formula milk 2 days later. With the infant in the right lateral position, ultrasonic images of the gastric antrum were obtained using the aorta bifurcational branch of superior mesenteric artery as constant landmarks. Measurements of antral cross sectional area(ACSA) were made before the feed and then sequentially, following its completion until ACSA returned to its pre-feeding state. Half-emptying time(t1/2) was calculated as the time taken for the ACSA to fall to half the maximal increment. The test was well tolerated by all subjects. RESULTS: There was a strong linear relationship between gastric volume and ACSA. The half-emptying time for breast milk was less than formula t1/2 breast milk 32.0+/-9.8 min; t1/2 formula 45.0+/-11.6 min, P=0.0004. CONCLUSION: The data demonstrate that human milk increases gastric emptying compared to formula. This has important implications for the management of preterm infants who have feeding intolerances.