Effects of red blood cell transfusion on neonatal cerebral hemodynamics: a TD-NIRS and DCS study

Anemia is a common problem in preterm neonates, and red blood cell transfusion (RBCT) is used to improve oxygen delivery. In order to limit the risk of possible complications new strategies to minimize the need for RBCTs are needed, as assessment of hemoglobin concentration in blood ([Hb]) alone appears to be an inadequate biomarker. In this study, we search for hemodynamic and metabolic thresholds to help define the need of RBCT in anemic newborns. The effect of RBCTs on cerebral tissue oxygen saturation (StO2) and blood flow (measured as Blood Flow Index, BFI) was estimated using a non-invasive hybrid diffuse optical device that combines Time Domain NIRS (TD-NIRS) and Diffuse Correlation Spectroscopy (DCS) techniques (BabyLux device). We enrolled 18 clinically stable neonates receiving RBCT at Neonatal Intensive Care Unit (NICU) of Ospedale Maggiore Policlinico in Milan. Tissue oxygen extraction (TOE) and the cerebral metabolic rate of oxygen consumption index (CMRO2I) were computed, the Wilkinson signed rank test for paired data was performed to compare data before and after RBCT. Preliminary results are in accordance with previous publications as regards cerebral oxygenation: a significant increase in StO2 (from 56.62 ± 5.20% to 63.85 ± 4.95%, p<0.05) and reduction in TOE (from 41.35 ± 5.9 % to 31.04 ±5.41%, p<0.05) were observed. The response in cerebral blood flow was smaller (only 10%) but also more variable, so conclusions regarding the effect of transfusion on cerebral oxygen metabolism are still uncertain.