CHANGES IN FAT CONCENTRATION OF HUMAN MILK WITH;' CONTINUOUS MECHANICAL PUMP INFUSION VERSUS INTERMITTENT BOLUS DELIVERY

Abstract

We studied changes in fat conc. and fat loss in human milk during 8 hr continuous infusion with 2 mechanical pumps (Harvard syringe [HARV] and Holter roller [HOLT] with Buretrol) and for comparison intermittent bolus delivery. We varied rate of pump infusion (1,4 or 7 ml/hr), state of homogenization and syringe position (HARV, tip vert or horiz). For each set of variables, infusions were repeated x4. Hourly samples were analyzed for fat. Infusion apparatus held only enough milk for an 8 hr. infusion, milk in the tubing being recovered by air infusion at the same rate. At 1 ml/hr with HARV and HOLT, 26-39% of fat was lost regardless of conditions. Fat conc. during infusion decreased to 32% of baseline for HARV and to 2% for HOLT, regardless of syringe position (HARV) or homogenization. During the 8th hr of infusion a large fat bolus was delivered (240±74% HARV & 435±131% HOLT > baseline fat conc). At 4 and 7 ml/hr fat losses for HARV and HOLT were 1-23% & 5-31% respectively and fat conc. decreased to 30-70% of baseline for HARV and 5-40% for HOLT. A large fat bolus was delivered during the 8th hr of infusion (144-333% HARV, 277-567% HOLT > baseline fat conc). Homogenization made no difference. For HARV changes in fat conc. could be decreased 12-22% by keeping syringe tip vert. With intermittent bolus delivery of milk (1,4,7 ml) no loss of fat, change in fat conc., or fat bolus occurred. Thus, for NG delivery of human milk to LBW infants, intermittent bolus is preferred. Continuous NG pump infusion should not be used because of large changes in fat conc. and fat loss.