1.1 BACKGROUND
Anaemia is a common finding in critically ill patients. Currently, the transfusion of stored
blood is the only treatment available to most patients. Despite this reliance on blood
transfusion there is a marked lack of data about both the efficacy of red cell transfusion
products and the clinical situations in which they are likely to be effective. It has recently
been suggested that red blood cell (RBC) transfusions may have detrimental effects in
critically ill patients and that these effects may be related to the transfusion of stored RBCs
in particular. It is well recognised that RBCs undergo many metabolic and structural changes
during refrigerated storage, these changes are termed the red cell storage lesion. The clinical
implications of the red cell storage lesion are not known.1.2 AIM
To assess the implications of the red cell storage lesion of the current UK RBC product,
namely leucodepleted RBCs stored in saline-adenine-glucose-mannitol additive solution,
using a combination of in vitro and in vivo studies.1.3 Methods
1. The quality of the current RBC product was assessed using in-vitro assays of RBC
oxygenation/de-oxygenation, namely P50 and the 2,3 diphosphoglycerate concentration,
and RBC deformability. ||
2. Radiolabel studies were performed to determine the 24 and 48-hour recovery of stored
allogeneic blood in critically ill patients. ||
3. The in-vivo regeneration of red cell 2,3 diphophoglycerate (2,3 DPG) in stored blood
transfused to critically ill patients was investigated. ||
4. Antigenic differences between donor and recipient were used to track allogeneic
RBCs following therapeutic transfusions to determine RBC survival using a nonradioisotopic technique.1.4 RESULTS
1. In-vitro tests showed that current collection processing and storage procedures:
(a) Result in a very rapid reduction in red cell 2,3 DPG concentration. Approximately
50% of 2,3 DPG had been lost by day 2 of storage and it was barely detectable by
day 14. The in-vitro Ps0 also decreased rapidly during storage; the time-frame of the
decrease matched that of the decrease in 2,3 DPG. ||
(b) Result in a slight reduction in red cell deformability.
2. The current red cell product, stored for between 10 to 29 days, had a mean 24-hour
recovery of 91% in critically ill patients. ||
3. Following transfusion to critically ill patients stored blood rapidly regenerated 2,3 DPG. ||
4. Red cell antigens were used to track allogeneic red cells for up to 12 weeks post¬
transfusion. The estimated median red cell lifespan was 104 days (range 86 to 124 days).1.5 CONCLUSIONS
Current red cell storage methods fail to maintain red cell 2,3 DPG and result in a loss of red
cell deformability. Although 2,3 DPG regeneration was found to occur rapidly it still took 24
to 72 hours for levels to approach normal; whether or not this is clinically significant is not
known.The current UK red blood cell product has good short-term and long-term survival
characteristics following therapeutic transfusion
