In Anaemic Preterm Infants, Regional Tissue Oxygenation Poorly Correlates With Conventional Indicators of Red Blood Cell Transfusion

Background: Packed Red Blood Cell Transfusions (PRBCT) are given to avoid tissue damage caused by oxygen delivery-consumption imbalances. PRBCT guidelines are based on assumption that low Haemoglobin along with symptoms of anemia correlates with poor oxygen delivery. Whether Hb and symptoms reliably reflect oxygen delivery-consumption imbalance (Fractional tissue oxygen extraction-FTOE) remains unresolved. The study aimed to correlate pre-transfusion Hb and symptoms of anemia with 4-hour pre-transfusion cerebral FTOE (FTOEc) and splanchnic FTOE(FTOEs) determined using continuous and concurrent monitoring of near-infrared spectroscopy and pulse oximetry.Methods: This prospective cohort study enrolled hemodynamically stable infants: Gestation<32 weeks; birth weight<1500 grams; postmenstrual age<37weeks: tolerating≥120 mL/kg/day feeds who received 15mL/kg PRBCT to treat anemia of prematurity.Results: The study enrolled 29 infants 13[44.8%] male; median[IQR] birth weight, 922[655-1064] g; gestation, 26.4[25.4-27.6]weeks; enrolment weight, 1549[1113-1882]g; and postmenstrual age, 33.6[32.3-34.9]weeks; respiratory support/low flow oxygen 24[82.2%]. There was negligible correlation between haemoglobin [median (IQR) 97 (87-100)g/L] and FTOEc (r=-0.12, p=0.54, n=29) as well as FTOEs (r=-0.09, p=0.64, n=29). There were no differences between symptomatic versus asymptomatic groups with respect to median FTOEc (p=0.67) as well as FTOEs (p=0.53).Conclusions: Pre-transfusion Hb and symptoms of anemia accurately reflect oxygen delivery-consumption imbalances in neither the brain nor gut. Whereas a lack of correlation with FTOEc can be conceptualized to be due to the brain-sparing effect, the lack of correlation with FTOEs is more concerning. Hence these results warrant larger studies incorporating FTOEc and FTOEs in addition to conventional criteria for PRBCT.Funding Information: The study was funded (for the purchase of NIRS sensors) by the Australian Women and Children's Research Foundation (www.ozwac.com.au).Declaration of Interests: The authors disclose no conflict of interest.Ethics Approval Statement: The study protocol including parental consent was approved by the human research ethics committee, Nepean Blue Mountain Local Health Committee (Approval number: Study 12/67 - HREC/12/NEPEAN/148).