Blood Donations, Storage, and Transfusions

            The use of blood transfusions in medicine is well established [1]. Scientific advances have rendered the process extremely safe through the introduction of donor-deferral strategies, infectious-disease testing, pathogen-inactivation methods, and recombinant DNA technologies [1]. These advances have significantly reduced the risk of transfusion-transmitted disease [1]. However, as concerns regarding infectious complications may have calmed, other risks have emerged, such storage for blood donations before use, especially in terms of duration [1].

            The Food and Drug Administration (FDA) permits packed red blood cells to be refrigerated for up to 42 days [1]. The mean storage time for blood donations before transfusion in the United States is 17 days [2]. This storage time allows blood center the flexibility to manage the available blood supply through seasonal swings, sudden demand, and transportation from one region of the country to another [1]. The issue is that long storage times have been associated with decreased quality of the blood that is transfused [1]. The mechanisms responsible remain unclear, but researchers suspect a variety of chemical and physical changes that occur in refrigerated red blood cells may be involved [2]. During storage, red blood cells experience increased membrane rigidity, loss of organic phosphates, and release of proinflammatory cytokines [1].

            Studies have suggested that prolonged red blood cell storage before transfusion increases mortality, risk of serious infections, and risk of multiorgan failure in hospitalized patients, counteracting the benefits of blood donations [2]. The storage-related change in red blood cell membrane rigidity and biochemical composition is associated with post-transfusion 24-hour survival [3]. The decreased deformability is thought to be linked to reduced ATP levels [3]. Restoration of ATP levels in red blood cell units has been shown to correct membrane alternations to a certain extent [3].

            A 2013 study at the Leiden University Medical Center sought to investigate whether the storage time of red blood cells relates to the mortality of recipients [4]. An observational cohort study analyzed data on patients who received transfusions from January 2005 through May 2009 [4]. Surprisingly, researchers found almost a 2-fold increase in mortality rate after the transfusion of fresh red blood cells (< 15 days old) compared with old red blood cells (> 15 days old) [4]. The authors suggested that analysis method may have affected the results of observational studies, and that randomized trials would be needed to confirm any reported associations [4]. An experimental study in mice found evidence that transfusion of older stored blood products produces a proinflammatory response associated with increased levels of tissue iron in the liver, spleen, and kidney [2]. The pro-oxidant effects of iron released after acute clearance of stored red blood cells may be responsible for some of the harmful effects of blood transfusion after prolonged storage [2].

            Whenever possible, a patient’s own blood is preferable to stored blood [3]. Therefore, the primary aim should always be to prevent blood loss in patients [3]. Effective bleeding control, cell salvage, and avoidance of unnecessary blood sampling for medical reasons are strategies to prevent anemia in most patients [3]. If allogenic blood transfusions are not viable, current experimental data suggest the use of fresh red blood cells, especially in critically ill patients who are in an oxygen-supply-dependent state [3].

References

1. Adamson, J. (2008). New blood, old blood, or no blood?. New England Journal of Medicine, 358(12), 1295-1296. doi:10.1056/NEJMe0800520
2. Hod, E., Zhang, N., Sokol, S. etc. (2010). Transfusion of red blood cells after prolonged storage produces harmful effects that are mediated by iron and inflammation. Blood, The Journal of the American Society of Hematology, 115(21), 4284-4292. doi:10.1182/blood-2009-10-245001
3. Almac, E., & Ince, C. (2007). The impact of storage on red cell function in blood transfusion. Best Practice & Research Clinical Anaesthesiology, 21(2), 195-208. doi:10.1016/j.bpa.2007.01.004
4. Middelburg, R., van de Watering, L., Briët, E., & van der Bom, J. (2013). Storage time of red blood cells and mortality of transfusion recipients. Transfusion Medicine Reviews, 27(1), 36-43. doi:10.1016/j.tmrv.2012.06.002