Splanchnic oxygen saturation is not associated with early growth in very preterm infants

Preterm birth is associated with poorer growth, possibly due to postnatal conditions that disrupt nutritional status. Previous studies found an association between low regional splanchnic oxygen saturation (rsSO2) and feeding intolerance (FI). We hypothesized that low rsSO2 is associated with poorer growth because of FI and associated impaired digestion and absorption.

We included infants with gestational age (GA) < 32 weeks and/or birth weight < 1.2 kilograms (kg). We excluded infants with chromosomal or congenital abnormalities, gastrointestinal diseases, and those who died. We collected daily 2-hour mean rsSO2 measurements, using near-infrared spectroscopy (NIRS), until the age of 7 days, and daily weight until the age of 21 days. We calculated the weekly relative growth rate (RGR) as the change in weight (g) divided by weight at the start of the interval (kg) and by the number of days. We used latent growth curve models to assess the association between rsSO2 and RGR.

We included 214 infants with a mean GA of 29.6 weeks and a mean birth weight of 1.4 kg. We did not find an association between rsSO2 in the first 7 days and RGR in the first 21 days of age. RGR in the first two weeks after birth was higher in lower GA and those born small for gestational age (SGA). Time to reach full enteral feeding (FEF) was longer in lower GA and in SGA, with GA showing the stronger association.

Longitudinal rsSO2 is not associated with early growth outcomes of very preterm infants.