Babies in the NICU are almost universally fed via a gavage tube at some point during their stay. The ones most in need of optimal nutrition are fed over the longest period of time via a gavage tube. The amount of calories required to mimic intrauterine growth is extremely high when compared to the body weight of the premature infant.
Of course, greater calorie expenditure occurs in the extrauterine environment due to the infant’s need to maintain their own body temperature, digest food, meet oxygen needs, particularly in the presence of respiratory distress and other bodily functions that require energy. Several studies have been done regarding fat loss when feeding infants via gavage tubing.
One of the earliest studies investigating this fat loss was published in 1978 and showed loss of up to 24% of the fat in the feeding.1 This group washed the tubing and showed some fat could be recovered in this manner. Other studies have measured the amount of fat left in the syringe at the end of the feeding and shown that syringe position effects fat delivery.2 A study by Brennan-Behm et al compared tubing diameter and fat loss.3 This group found that the smaller bore tubing resulted in less fat loss but was still significantly more fat loss than intermittent gravity feedings. In a very recent study, a comparison was made between a gravity feeding over 2.5 to 4 minutes and syringe pump feedings given over 1 hour and 2 hours.4 This study was performed using donor breast milk. Fat content was measured before the feeding as a control and then after each delivery method. It was found that fat loss was not significantly different between the 1 hour and 2 hour infusion times but both of these showed significantly higher fat loss than the gravity feeding. Another recent study investigated the loss of fat as well as other macronutrients during tube feedings.5 In this study, the milk was fortified with two different fortifiers and nutrient loss was also compared between the types of nutrients. Feedings were delivered continuously, over 30 minutes and by gravity. Nutrient loss, specifically calcium and fat, was greatest in the continuously infused feeding. Continuous feedings showed a fat loss as high as 50%. In addition, two different types of infusion pumps were utilized. One pump showed significantly lower fat loss than the other, although both were significantly higher than the 30 minute infusion or gravity infusion. They postulated that this may have been related to a lack of a reservoir in the second type of pump and shorter tubing. Interestingly, this group found less nutrient loss, regardless of delivery method, with liquid human human milk fortifier versus a powdered bovine milk fortifier. This was thought to be due to the fact that the liquid fortifier mixed better with the donor breast milk being fed for the research simulation.
So, what is the clinical effect of this fat loss? Studies have not yet been done to convincingly evaluate this clinical effect and indeed, it may be very difficult to show the effect. Many other things can confound growth so that comparisons would be difficult. A Cochrane review of studies comparing continuous versus intermittent bolus feedings via nasogastric or orogastric feeding tube did not show any difference in time to full feeds or time to discharge.6 Weight gain was faster in infants less than 1250 gms when fed by continuous nasogastric feeding method but the number of infants included in the studies reviewed as well as variability in outcome measures does not provide sufficient evidence to recommend this method of feeding over the intermittent bolus feeding method. Therefore, additional studies are needed evaluating the clinical effect of this fat loss and perhaps correlating degree of fat loss with growth rates in infants.
Many people believe that gravity feeds are not well tolerated by premature infants who are at risk for gastroesophageal reflux. Slower, smaller volume feedings may indeed be helpful in a subpopulation of infants suffering from reflux but is not indicated or needed for every premature infant. These infants, particularly, need the extra calories and fat from their feedings so if indeed, a significant amount is lost in the tubing, it may be advantageous to provide gravity feedings to these infants as well, simply at a more controlled rate i.e. over 10 to 20 minutes. At least delivering feedings via gravity until shown that the patient needs another type of delivery seems reasonable. In general, use of smaller bore, shorter tubing when continuous or slower paced feedings are required seems to decrease the amount of fat loss. In addition, perhaps flushing of the extension tubing to “wash out” some of the fat and deliver it to the infant may be helpful.
1. Brooke OG, Barley J. Loss of energy during continuous infusions of breast milk. Arch Dis Child. 1978;53:344-345.
2. Narayanan I, Singh B, Harvey D. Fat loss during feeding of human milk. Archives of Diseases in Children. 1984;59(5):475-477.
3. Brennan-Behm M, Carlson GE, Meier P, Engstrom J. Caloric loss from expressed mother’s milk during continuous gavage infusion. Neonatal Network. 1994;13(2):27-31.
4. Brooks C, Vickers AM, Aryal S. Comparison of lipid and calorie loss from donor human milk among 3 mthods of simulated gavage feeding. Advances in Neonatal Care. 2013;13(2):131-138.
5. Rogers SP, Hicks PD, Hamzo M, Veit L, Abrams S. Continous feedings of fortified human milk lead to nutrient losses of fat, calcium and phosphorus. Nutrients. 2010;2:230-240.
6. Premji SS, Chessell L. Continuous nasogastric milk feeding versus intermittent bolus milk feeding for premature infants less than 1500 grams. Cochrane Database of Systematic Reviews 2011, Issue 11. Art. No.: CD001819. DOI: 10.1002/14651858.CD001819.pub2
Looking for additional reading on feeding tubes?
View Sandy Beauman’s related blog entry, Frequency of Feeding Tube Changes.