Decreased the iron storage of preterm neonates at the time of birth, inability to enteral feeding with breast milk at the first days or weeks of life, frequent blood sampling and decreased the level of erythropoietin leading to anemia and packed cell transfusion frequently during the admission time of premature infants(11). Although packed cell transfusion is a lifesaving treatment modality, unfortunately can be lead to some complications. A recently known probable complication is NEC and feeding problems which for decreasing this complication, withholding enteral nutrition during the time of transfusion of preterm babies is suggested(8).In this clinical trial study, we aimed to evaluate the correlation between packed cell transfusions and feeding tolerance in well preterm infants.,Our results showed that discontinuing feeding had no effect on the feeding tolerance of patients and it seems that the liberal protocol of feeding regardless of the time of transfusion in well premature babies is safe.
To remove, the effect of the other risk factors of feeding intolerance such as sepsis, NEC, HIE, we include just well premature infants without any history of mentioned problems. In some recent studies, 25–35%of NEC has been related to PCT(12). There is a lot of research on this issue but the results of them were inconclusive so far there isn't standard protocol for the feeding of preterm infants during transfusion(13).
Similar to our research, in the study by VT Le in case-crossover research for assessment of the NEC and the fortification and volume increase of milk, in 63 preterm infants<32 weeks of gestation, they did not detect any effect of the fortification and volume of the milk and GI problems(14), inversely some other studies such as Alfaleh showed that PCT was associated with the lower rate of NEC in preterm infants(15).
The mean age of the newborns in both of the intervention and control groups of our research was17 and 15 days respectively, notably, the inclusion criteria of our research was well preterm infants, considering that, the first days of life in premature patients are concurrent with more systemic problems such as respiratory distress syndrome(RDS), need to mechanical ventilation and surfactant therapy or sepsis, which can cause feeding intolerance and confound the results of our research, most of our patients were older than 2 weeks which had a better general condition for including our research.
Many reports are indicating the impact of the delivery mode on the neonatal outcome of preterm babies. Intraventricular hemorrhage, hypoxic-ischemic encephalopathy (HIE), RDS are the neonatal problems affected by mode of delivery. Our research did not show any significant difference in the rate of NEC or feeding intolerance after transfusion in preterm babies delivered by C/S or NVD (P=.239) resembles the study by Monika Bajaj (P=0.37)(16).
Despite the emphasis on the feeding in preterm infants by expressed breast milk of own mothers Unfortunately, the overall rate of breastfeeding in the population of our research was 42%. Our hospital is a referral center without nursery and most of the patients referred from the distance areas, so we don’t access to breast milk all the times and due to the lack of milk bank in our hospital, the use of formula as an alternative substance is logical. In spite of the more using of formula in the control group of our patients, the rate of feeding intolerance was similar between the two groups.
There are inconclusive recommendations about the duration of withholding the nutrition and packed cell transfusion. Some research has recommended discontinuing enteral feeding in patients 1-4 hours before the time of transfusion, some the others studies don’t give milk to the baby during or after transfusion even to24 hours later(7). We withheld feeding of neonates in intervention groups just during the transfusion and observed all patients in intervention and control groups 24-72 hours after transfusion, due to the definition of TANEC that is the appearance of the NEC during 48-72 hr after transfusion. As we mentioned we did not find any difference in feeding intolerance between two groups.
Anemia as an underlying risk factor for TANEC, cause the subclinical intestinal mucosal injury precedes the overt clinical signs and symptoms of enterocolitis. Probable mechanisms include immaturity of re-oxygenation injury in the anemic gut, the splanchnic vascular bed, and immune mechanisms similar to those seen in transfusion-related lung injury (TRALI)(17). Then transfusion of the packed cell may not be a primary cause of the intestinal injury rather, be an additive risk factor to underlying mucosal injury by severe anemia. By this hypothesis, the level of hemoglobin and severity of anemia can be effect the incidence of feeding intolerance.
Then, some research analyzed the effect of the level of hemoglobin on the occurrence of TANEC and resulted in a significant effect on the incidence and severity of the NEC. These studies concluded that lower levels of hemoglobin have been associated with an increased risk of NEC(18). In our research, the level of hemoglobin in the control group was significantly lower than the intervention group (7.56 mg/dl vs. 8.27 mg/dl, P=0.021), but there wasn’t any statistically significant difference in feeding intolerance between two groups. This result may be due to the low level of difference between the values of hemoglobin in two groups.
The study was done by Cris Derienzo in a retrospective cohort research in 148 very low birth weight infants; they compare transfusion-associated NEC (TANEC) with this problem without correlation with transfusion. They found that TANEC was observed in smaller premature patients and lower levels of hematocrit before transfusion, in other words, more severe anemia in premature infants was associated with a higher incidence of TANEC. The authors of this article recommended that in infants at higher risk of NEC, maintenance of the higher level of hemoglobin and hematocrit is a protective factor(19).
Also in research by Ravi M. Patel and colleagues in very low birth weight infants with the age of 0-5 days, they found that severe anemia (not packed cell transfusion) was associated with NEC(20). But in our study compared to this research, the mean age of neonates was higher than the age of our patients and the severity of anemia didn’t have any significant effect in the feeding intolerance.
The prolonged hospitalization time of preterm infants is concurrent with the repeated need for PCT. In our research 5(14.3%) of patients in intervention groups and 8(22.9%) of the control group had the previous history of transfusion without any significant effect on the rate of feeding intolerance. It is unclear whether repeated transfusion has an additive effect on feeding intolerance or NEC. However, the time interval between repeated transfusions is important for this effect. In research was done by Yu-Cheng Wang the number of RBC transfusions was higher in participants with NEC(21).
The limitation of our study was the low sample size of the patients, although, in spite of this limitation, the methodology of our research was suitable for judgment in this issue.