Cerebral blood flow and oximetry response to blood transfusion in relation to chronological age in preterm infants

Abstract

word count: 400 words (maximum 400) Manuscript body word count: 4057 words (maximum 6000) 2 | P a g e AbstractPreterm infants frequently receive blood transfusion during their stay in neonatal unit, and its impact on organ perfusion and oxygenation is not clear. The aim of the study was to measure the effect of blood transfusion on cerebral blood flow and oxygenation in preterm infants in relation to chronological age.Fifty nine infants were studied: group 1=20, group 2=21 and group 3=18 infants with median age (range) at transfusion of 5 (1-7), 14 (8-27) and 45 (29-68) days respectively. Gestational age and birth weight of infants between groups were similar. Pre-transfusion vital parameters were similar between the groups except the heart rate was significantly higher in group 1 compared to group 3 (p=0.02). The mean BP increased significantly in all three groups and there were no significant changes in other vital parameters following transfusion.There was no change in pre and post transfusion pCO2 and pH in blood gas. The mean pretransfusion Anterior Cerebral artery (ACA) time averaged mean velocity (TAMV) increased significantly with chronological age (p<0.001), and ACA Peak Systolic Velocity (PSV) also increased with chronological age of infants but this was not significant. Pre-transfusion ACA TAMV and PSV decreased significantly (p≤0.04), and there was no change in ACA Resistance Index (RI) and Pulsatility Index (PI) following transfusion in infants of all 3 groups. The pre-transfusion mean Superior Vena Cava (SVC) flow decreased significantly in Group 1 (p=0.03) and Group 3 (p<0.001) following transfusion, but the change was not significant in the Group 2 infants (p=0.16). The mean pre-transfusion cerebral tissue oxygenation index (cTOI) levels were significantly lower in group 3 compared to group 1 (p=0.02). The cerebral tissue haemoglobin level cTHI (p<0.001) and cTOI (p<0.05) increased significantly post-transfusion in all the three groups. The percentage increase in post-transfusion cTOI from baseline was 5%, 11% and 12% in group 1, group 2 and group 3 3 | P a g e infants respectively. On comparing infants with PDA (n=14) to gestational and chronological age matched controls (n=14), there was no significant difference in these measurements.Baseline cTOI decrease and ACA TAMV increase with increasing chronological age. Blood transfusion increased cTOI and cTHI, and decreased ACA TAMV in all age group of infants but the proportion of response is different. PDA had no impact on the baseline cerebral oximetry and blood flow as well as changes following transfusion. Future transfusion trials should take into account the impact of postnatal age on cerebral oximetry and blood flow.

Blood transfusions in preterm infants: changes on perfusion index and intermittent hypoxemia

“…Interestingly, in Epoch 1, patients on mechanical ventilation had no improvement or worsening in oxygenation after RBC transfusion. We speculate that the findings seen in the first week of life in ventilated infants may relate to patient characteristics including immaturity of compensatory mechanisms, severe lung disease with poor pulmonary reserves, and subsequent lung fluid overload from RBC transfusion . Increased FiO 2 requirement before RBC transfusion was associated with a significant decrease in IH measures after transfusion during Epoch 1.…”

“…The effect of RBC transfusion on PI may be related to volume expansion. In contrast, RBC transfusion effect on IH is likely due to changes in oxygen‐carrying capacity and stabilization of oxygenation …”

“…The lack of benefit may be related to the already low incidence of IH during this period . Other factors may include inadequate compensatory mechanisms to overcome the changes in blood flow, volume status, and blood viscosity associated with RBC transfusion during early postnatal life . Furthermore, the higher proportions of high‐affinity fetal hemoglobin in early postnatal life may have an impact on the effect of RBC transfusion on oxygenation .…”

“…Red blood cell (RBC) transfusion results in IH improvement, particularly beyond the first week of life . Perhaps the main rationale for RBC transfusion in preterm infants is improvement in oxygenation . There are two proposed mechanisms for beneficial effect of RBC transfusion on oxygenation.…”

“…1 Perhaps the main rationale for RBC transfusion in preterm infants is improvement in oxygenation. 6 There are two proposed mechanisms for beneficial effect of RBC transfusion on oxygenation. The first relates to greater cardiovascular stability with increased perfusion to the respiratory control network leading to improved central respiratory drive and subsequent less IH.…”