Gut and cerebral perfusion and oxygenation in preterm infants receiving blood transfusion

Abstract

Background and Aim: Preterm infants frequently receive blood transfusion (BT) during their stay in the neonatal unit. The aim of this study was to measure the effect of BT on cerebral and gut blood flow and oxygenation in preterm infants in relation to postnatal age. Another aim of the study was also to investigate the influence of measured pre-transfusion RCV on gut perfusion in preterm infants receiving first blood transfusion for clinical indication using NIRS and Doppler ultrasound scan. Methods: Preterm infants admitted to neonatal unit were recruited to three postnatal age groups: 1 to 7 days (group 1; n=20), 8 to 28 days (group 2; n=21) & ≥29 days of life (group 3; n=18). Pre and post-BT Anterior Cerebral artery (ACA) Time Averaged Mean Velocity (TAMV) and Superior Vena Cava (SVC) flow were measured to assess cerebral blood flow. Pre and post-BT Superior mesenteric artery (SMA) peak systolic velocity was measured to assess gut or splanchnic blood flow. Cerebral and gut Tissue Haemoglobin Index (THI), Oxygenation Index (TOI) were measured from 15-20 minutes before to 15-20 minutes post-BT using NIRS. Cerebral and gut fractional tissue oxygen extraction (FTOE) was calculated from the TOI and saturation of oxygen (SaO2). Vital parameters and blood pressure (BP) were also measured continuously from overhead monitors. Pretransfusion red cell volume (RCV) was measured by fetal haemoglobin (HbF) dilution method and compared with the cerebral and gut perfusion and oxygenation changes following blood transfusion. The cerebral and gut perfusion and oxygenation were also measured over a three hour period in 12 control infants not receiving blood transfusion. Results: There were 71 infants included in the study; of them 59 were study infants receiving blood transfusion and 12 were control infants. Amongst the vital parameters, mean BP increased significantly, and there was no significant change in heart rate (HR), respiratory rate (RR) or SaO2 following BT. Pre-transfusion ACA TAMV was higher in Group 2 and 3 compared to Group 1 (p<0.001) which remained significant after multivariate analysis (p<0.05). Pretransfusion ACA TAMV decreased significantly (p≤0.04) in all 3 postnatal age groups; pre-transfusion SVC flow decreased significantly in Group 1 (p=0.03) and Group 3 (p<0.001) following transfusion. Pre-transfusion cTOI was significantly lower in Group 3 compared to Group 1 (p=0.02) which remained significant after multivariate analysis (p<0.011). The cTHI (p<0.001) and cTOI (p<0.05) increased significantly post-transfusion in all three postnatal age groups. PDA had no effect on these measurements. Pre-transfusion SMA PSV increased with postnatal age (group 3 vs. group 1: p<0.01; CI 0.6 to 0.1), proportion of feeds (>50% feeds: 0.91±0.4 vs. <50% feeds: 0.71±0.4 m/sec, p<0.01); and decreased with presence of PDA (closed PDA: 0.94±0.4 vs. open PDA: 0.68±0.3 m/sec, p=0.006, CI 0.07 to 0.45); but remained unaltered following transfusion. The pre-transfusion sTOI varied with postnatal age (Group 2:44.6 vs. Group1: 36.7%; p=0.03, CI -0.6 to -15.2) on univariate analysis but was not significantly different on multivariate analysis; pre-transfusion sTOI was not influenced by feeds or presence of PDA. The sTHI and sTOI increased (p<0.01) and sFTOE decreased (p<0.01) significantly following transfusion in all postnatal age groups.