I have discussed before evidence about whether the pattern of introduction or advancement of feeds affects NEC. I noted that there is only one out of a large number of trials of feeding introduction and advancement which has shown an effect on necrotising enterocolitis, the large preponderance of the literature shows no such effect.
Two new studies also fail to show an effect. One is a historical cohort study, (Maas C, Mitt S, Full A, Arand J, Bernhard W, Poets CF, Franz AR: A historic cohort study on accelerated advancement of enteral feeding volumes in very premature infants. Neonatology 2013, 103(1):67-73.) the authors increased the starting feed volume and the feeding advancement volume, and compared GI complications before and after, the new protocol being to start at 20 mL/kg/d and advance at between 25 and 30 mL/kg/d, for all babies less than 1500g and less than 32 weeks gestation, during both time periods feeds were started on the first day of life. The results showed that full feeds were achieved more quickly in the later group, (6 days vs 8 days on average) and there was no increase in GI complications.
The other study is from Columbia, it is in Spanish, but with the English abstract and a smattering of Spanish, I think I have the gist, (I tried Google translate, but it kept telling me the page was already in English! Perez LA, Pradilla GL, Diaz G, Bayter SM: [necrotizing enterocolitis among preterm newborns with early feeding]. Biomedica : revista del Instituto Nacional de Salud 2011, 31(4):485-491.) The authors randomized 239 babies between 750 and 1500 grams birth weight to start their feeds either at 24 to 48 hours of age or on the 5th day. Both groups had an increase of about 20 mL/kg/d thereafter. There was no difference in complications, but better nutrition in the early group.
Now I don’t think that routinely waiting to start feeds until after 24 hours is necessary, but the authors performed a nice trial to show that you certainly don’t need to wait 5 days, which they note was their usual practice before the study.
This is yet more data to show that the way that we feed preterm babies has no effect on NEC. So why is the belief so prevalent? I think that NEC is a serious, sometimes devastating disease, and we humans are always trying to find reasons and patterns in what happens to us. NEC usually presents after feeds are started, being relatively uncommon in babies who have never been fed, so the impact of feeds, and how they are given is a reasonable issue of concern. So if you see a baby who has NEC, and notice that the day before they had the NEC they had their feeds increased, it starts to make you think; then if you have a little run of cases, and you change your feeding protocol to become more conservative it is likely (regression to the mean) that NEC will be less frequent afterward. So confirming to you that you did the right thing. The next time you have an outbreak you become even more conservative, and low and behold, the NEC goes away again. This way you end up with some centers with extremely slow feed advancement, and others, who never bought into the association, who feed much more quickly, and year by year, no consistent relation between feeding patterns and NEC in large databases.
One further point, both of the studies above used gastric residuals to determine if the feeds were tolerated, but they used very different guidelines, one tolerated 1-2 mL and less than 30% of the feeds, the other tolerated between 25 to 50%. I previously worked in a center where we stopped measuring residuals; during a period of 8 years I was never bothered by the report of a residual, the only measurable effect was a reduction in periods of feed interruptions. Here at Sainte Justine, since our new feeding protocol was introduced we have also stopped routine measurement of residuals, and again the only obvious effect is to reduce the number of interruptions of feeds.
What would the best evidence based feeding schedule look like for a very immature infant?
1. Start feeds on day 1, at 20 mL/kg/d (should there be exceptions? I think babies in shock could wait a day or 2, otherwise probably not)
2. Use breast milk, with probiotics.
3. Increase by 30 mL/kg/d
4. Add breast milk fortifier immediately (we add after the baby is to receive 25 mL a day, as we prepare the milk every 24 hours and we don’t want to waste precious breast milk. I sachet of fortifier is mixed with 25 mL of breast milk)
5. Don’t measure residuals.
6. Don’t measure abdominal circumference.
The problem comes on day 1 if the Mother has not yet produced breast milk, what do you do? Donor milk, wait for mother’s milk, or give a couple of days of formula? We have opted to wait for mother’s milk (colostrum) as we don’t currently have a source of donor milk, but of course donor milk is not colostrum… Food for another study I think.