Washed versus unwashed red blood cells for transfusion for the prevention of morbidity and mortality in preterm infants

Background: Infants born very preterm often receive multiple red blood cell (RBC) transfusions during their initial hospitalisation. However, there is an increasing awareness of potential adverse effects of RBC transfusions in this vulnerable patient population. Modification of RBCs prior to transfusion, through washing with 0.9% saline, may reduce these adverse effects and reduce the rate of significant morbidity and mortality for preterm infants and improve outcomes for this high-risk group. Objectives: To determine whether pre-transfusion washing of RBCs prevents morbidity and mortality in preterm infants. Search methods: We used the standard search strategy of the Cochrane Neonatal Review Group to search the Cochrane Central Register of Controlled Trials (CENTRAL 2015, Issue 7), MEDLINE via PubMed (31 July 2015), EMBASE (31 July 2015), and CINAHL (31 July 2015). We also searched clinical trials databases, conference proceedings, and the reference lists of retrieved articles for randomised controlled trials and quasi-randomised trials. Selection criteria: Randomised, cluster randomised, and quasi-randomised controlled trials including preterm infants (less than 32 weeks gestation) or very low birth weight infants (less than 1500 g), or both, who received one or more washed packed RBC transfusions. Data collection and analysis: Two review authors independently assessed the eligibility of the trials. We identified four studies from the initial search. After further review of the full-text studies, we found one study meeting the selection criteria. Main results: We included a single study enrolling a total of 21 infants for analysis in this review and reported on all-cause mortality during hospital stay, length of initial neonatal intensive care unit (NICU) stay (days), and duration of mechanical ventilation (days). There was no significant difference in mortality between the washed versus the unwashed RBCs for transfusion groups (risk ratio 1.63, 95% confidence interval (CI) 0.28 to 9.36; risk difference 0.10, 95% CI -0.26 to 0.45). There was no significant difference in the length of initial NICU stay between the washed versus the unwashed RBCs for transfusion groups (mean difference (MD) 25 days, 95% CI -21.15 to 71.15) or the duration of mechanical ventilation between the washed versus the unwashed RBCs for transfusion groups (MD 9.60 days, 95% CI -1.90 to 21.10). Authors' conclusions: We identified a single small study. The results from this study show a high level of uncertainty, as the confidence intervals are consistent with both a large improvement or a serious harm caused by the intervention. Consequently, there is insufficient evidence to support or refute the use of washed RBCs to prevent the development of significant neonatal morbidities or mortality. Further clinical trials are required to assess the potential effects of pre-transfusion washing of RBCs for preterm or very low birth weight infants, or both, on short- and long-term outcomes.