ISPUB.COM The Internet Journal of Medical Technology Volume 5 Number 1 DOI: 10.5580/2789 1 of 9 Investigating Direct Non-Age Metrics of Stored Blood Quality Loss K Alfano, M Tarasev Citation K Alfano, M Tarasev. Investigating Direct Non-Age Metrics of Stored Blood Quality Loss. The Internet Journal of Medical Technology. 2011 Volume 5 Number 1. DOI: 10.5580/2789 Abstract Long storage times for blood products are often unavoidable. Product age is essentially the only indicator used today for Red Blood Cell (RBC) quality loss during storage. Much controversy persists over the impact of RBC age on transfusion outcomes, as studies on this remain inconclusive. Such inconsistency may arise from unit-to-unit variability, which likely introduces some age-independence to RBC state. Thus, quality metrics other than storage time could aid with inventory management and/or treatment decisions. RBC membrane mechanical fragility is proposed here as one such candidate in vitro metric: it aggregately reflects a range of biochemical and biomechanical changes associated with storage lesion, and can provide a more comprehensive characterization of particular units than other properties. Preliminary data suggest this property can vary substantially among units of equal age, and further work now in progress is investigating its correlation to post-transfusion red cell survival in vivo. INTRODUCTION Transfusing Red Blood Cells (RBC) has been a common treatment for anemia since the introduction of preservative solutions in the mid-20 th century. In severe hemorrhage cases, massive transfusions of up to 10-15 units are often required. For example, during 5 years of US military operations, about 86,000 units of RBC and whole blood (WB) were administered to about 5,000 patients (1, 2). While the benefit of transfusion for severe hemorrhage cases is well accepted, multiple studies suggest that RBC transfusions nevertheless can fall short of achieving their desired clinical effect – particularly for certain vulnerable patient groups – prompting reexamination of transfusion protocols and the preserved efficacy of stored packed RBC (see (3-8) for reviews). Two main reasons have been proposed to account for reports of suboptimal transfusion efficacy: 1) adverse effects from non-RBC cells in transfused blood, and 2) changes in RBC resulting from prolonged storage – so-called “storage lesion” (9). Regarding the first, the presence of plasma factors and blood formed elements (e.g. leukocytes and platelets) was identified as potentially affecting in vivo performance of stored packed RBC (6, 10-13). Much evidence now demonstrates the benefits of leukocyte filtration (leukoreduction) for certain patient groups, although some controversy over this treatment still continues despite strong endorsement by the US Food and Drug Administration ((14-16)). In this article we discuss the second reason, RBC storage lesion, suggesting that age-independent metrics could enable better informed treatment and/or inventory- planning decisions – particularly in situations where “fresh” blood is rarely even an option. BACKGROUND: STORAGE LESION AND THE AGE DEBATE Current civilian storage needs in the US result in an average RBC unit age of 21 days at transfusion (17), with the maximum permitted shelf life being 42 days. A survey of 1,500 American blood banks found that 20% of RBC units were ≥ 28 days old (18, 19). For rare blood types such as O- Negative, more than 60% of stored blood units were ≥ 28 days old (20). On the military side, collected blood is processed into components and shipped by air to operation theaters; the increased complexity of providing regular RBC shipments to combat support hospitals results in units being aged 27-32 days upon delivery. By the time of transfusion, these units are 32 days and older, as reported by Spinella et.al. (21).