Study on Transfusion Effects in Preterm infants

Neonatal anemia is common in preterm infants. Anemia may lead to hypoxia,
possibly resulting in cell damage. A red blood cell (RBC) transfusion is an
intervention aiming to rapidly improve oxygen transport to vital organs, such
as the brain and the gut.
Anemia and RBC transfusions result in low and high organ oxygenation
respectively. Both might be harmful, and especially high variation in
oxygenation may lead to damage in vulnerable organs, such as the brain and the
gut. As erythropoiesis is partly upregulated by hypoxia, there might be an
association between these oxygenation values and the expression of
erythropoietin (epo), which is the essential growth factor for the production
of erythrocytes. Also, the expression of the epo receptor in the intestinal
enterocytes might influence growth and development of the gastrointestinal
tract, which may protect against necrotizing enterocolitis (NEC) in preterm
born infants. Epo may also provide neuroprotection for different pathways of
brain injury. In the brain, epo, therefore functions as both an important
growth factor and a neuroprotective agent.
The expression of epo is controlled by DNA methylation. DNA methylation, i.e.
adding a methyl group to the DNA molecules, results in inactivity of the gene.
This DNA methylation has been shown to partially depend on oxygen and nutrient
supply. Anemia leads to decreased oxygen transport and decreased organ
oxygenation, whereas RBC transfusion increases oxygenation. It is unknown
whether anemia and/or RBC transfusion are related to the expression of epo in
gut cells through these various levels of oxygenation. We will therefore
explore whether epo regulation and expression in intestinal cells may be
associated with the course of hemoglobin (Hb) levels. Furthermore, we will
explore if epo regulation and expression may also be associated with anemia,
RBC transfusions, oxidative stress, and organ oxygenation in the neonatal
period. Secondary, we will evaluate the clinical consequences and the
neurological outcome of the variable oxygenation levels.

The first objective is to explore whether epo regulation and expression, at the
age of two weeks after birth and three to six months post-term, are associated
with the course of Hb levels. Furthermore, we will assess if epo regulation and
expression are also associated with anemia, RBC transfusions, oxidative stress,
and cerebral and intestinal oxygenation in preterm infants during the early
neonatal period.
Our second objective is to evaluate the association between various oxygenation
levels and hypoxic intestinal cell damage, the prevalence of NEC and its
grading up to 40 weeks postmenstrual age, the neurological condition during
anemia and after RBC transfusion, and the neurological outcome at three months
post-term.

Prospective observational cohort study.

This study cannot be performed in another population, as the lack of knowledge
about the possible association between anemia and RBC transfusions, and the
expression of epo in gut cells, through the various levels of oxygenation is
typical for preterm infants.

Burden: All infants participating in the study are subjected to routine
neonatal intensive care. This study is an observational study, implying minimal
extra care; therefore there is minimal burden and risk associated with
participation.
First, the fecal samples will be collected from the diaper, using a scooper.
The samples will be collected during routine handling moments, so the infant
will not be disturbed. Parents will be asked to send a feces sample of their
infant around the age of three to six months post-term. They will receive a
kit, which contains a preservation buffer. The stool sample is stable at room
temperature for months and can be send by mail.
Second, we intend to measure the epo concentration in the second week of life
to validate the DNA methylation in the fecal samples, by sampling 100
microliter extra blood, which is about three drops, only when blood will be
drawn for clinical purposes. The 100 microliter umbilical cord blood will be
sampled after birth.
Third, monitoring of cerebral and intestinal regional tissue oxygen saturation
is routine clinical care in all preterm infants admitted to the NICU at the
UMCG, and near-infrared spectroscopy (NIRS) is a continuous and non-invasive
method to use. For the purpose of this study possibly extra NIRS measurements
will be needed in the third and fourth week of life, during the time around and
after the infant receives an RBC transfusion.
Fourth, the urinary samples will be collected non-invasively by a small gauze
in the diaper. The samples will be collected during routine handling moments,
so the infant will not be disturbed.
Fifth, evaluating GMs is a widely accepted non-invasive method to assess the
neurological neonatal outcome. Before and after the first RBC transfusion the
infant will be video-recorded for 30 minutes, and at the age of three months
(+/- 2 weeks) post-term for 10 minutes, with the infant in an actively awake
state, comfortably dressed, with uncovered arms and legs. The camera will be
placed in a way that caregivers are not hindered by the camera and do not lose
sight on the monitor. Therefore, video recording GMs will not interfere with
clinical care.

Benefits and risks: The study may provide more insight in the mechanism of the
epo regulation and expression, as a neuroprotective agent, and as a factor
influencing growth and development of the gastrointestinal tract. It may
elucidate the relation between epo regulation and expression on the one hand
and anemia and RBC transfusions and subsequent oxygenation of organs on the
other. This might be of importance for a normal neurological development and to
prevent NEC, increasing quality of life of preterm infants.