Anemia of Prematurity and Cerebral Near-Infrared Spectroscopy: Should transfusion thresholds in preterm infants be revised?

OBJECTIVE: To determine the impact of progressive anemia of prematurity on cerebral regional saturation (C-rSO(2)) in preterm infants and identify the hemoglobin threshold below which a critical decrease (>2 SD below the mean) in C-rSO(2) occurs. STUDY DESIGN: In a cohort of infants born ≤30 weeks EGA, weekly C-rSO(2) data were prospectively collected from the second week of life through 36 weeks post-menstrual age (PMA). Clinically-obtained hemoglobin values were noted at the time of recording. Recordings were excluded if they were of insufficient duration (<1 hour) or if the hemoglobin was not measured within 7 days. Statistical analysis was performed using a linear mixed effects-model and ROC analysis. ROC analysis was used to determine the threshold of anemia where C-rSO(2) critically decreased >2 SD below the mean normative value (<55%) in preterm infants. RESULTS: 253 recordings from 68 infants (mean EGA 26.9±2.1 weeks, BW 1025±287g, 49% male) were included. 29/68 infants (43%) were transfused during hospitalization. Mixed-model statistical analysis adjusting for EGA, BW, and PMA revealed a significant association between decreasing hemoglobin and C-rSO(2) (p<0.01) in transfusion-naïve infants but not in transfused infants. In the transfusion naïve group, using ROC analysis demonstrated a threshold hemoglobin of 9.5g/dL (AUC 0.81, p<0.01) for critical cerebral desaturation in preterm infants. CONCLUSIONS: In transfusion-naïve preterm infants, worsening anemia was associated with a progressive decrease in cerebral saturations. Analysis identified a threshold hemoglobin of 9.5g/dL below which C-rSO(2) dropped >2 SD below the mean.