If you are a member of the blood banking fraternity, this article is just the right for you. It covers various aspects of the proper storage of blood and its components.
After processing blood into its components, they need safe and proper storage, mainly due to two reasons: maintaining the constituents’ therapeutic efficacy and life span and preventing bacterial growth.
Whole blood
You should store whole blood and red cell concentrate between 2 to 6 degrees C.
If the storage temperature falls below 2 degrees C, it can cause freezing of the red cells. The freezing will cause injury that can result in haemolysis.
Hemolyzed blood is harmful. If you transfuse such blood to a patient, fatal consequences might arise.
If the storage temperature exceeds 6 degrees C, it will provide a suitable environment for overgrowth of non-specific bacteria which entered the blood unit during collections or component preparation.
When you store blood at 2-6 degrees C, it reduces the glycolysis rate of the continued metabolism of red cells.
Fresh Frozen Plasma (FFP)
Usually, the need for FFP transfusion arises while restoring or maintaining the clotting mechanism. FFP also becomes useful when there is a need for a volume replacement when crystalloids and colloids are not used.
You can prepare FFP by removing the plasma from a blood unit within 6 hours of collection and snap freezing at -70 degrees C and storing at -30 degrees C.
The freezing speed is an essential factor in maintaining the coagulation factors such as F VIII and F V.
When it comes to the storage of liquid plasma, it calls for a storage temperature of -30 degrees C or lower.
It has an adequate amount of plasma proteins but lacks the labile coagulation factors FVIII and FV. Usually, fresh frozen plasma and frozen plasma have a shelf-life of one year. And it would help if you stored them in plasma storage freezers.
Platelets
Blood banks usually store platelets as concentrates. There are two ways of harvesting platelets– from platelet-rich plasma (PRP) or buffy coat and resuspended in 50 ml of plasma.
Banks should store platelets at 22 degrees C in plasma under the right conditions, maintaining the pH above 6.8.
If there is a fall in platelet pH concentration due to lactate production from platelet glycolysis, it can lead to loss of viability. Platelet concentrate bears a shelf-life of only five days.
It is a must to agitate platelet concentrates. It needs to be done gently and constantly on a flatbed agitator to maintain viability.
If there is no agitation, there will be a rapid fall in pH due to lactic acid metabolites collection.
What are the Physical and Biochemical Effects of Blood Storage?
The storage conditions are essential factors for effective blood storage. The conditions in which you store blood will cause changes in the physical and chemical properties of blood, which in turn determine the red cell recovery.
There can be many abnormalities that can result from blood storage, such as, effect on:
Red Cell Function and Survival
The red cell depends on the anaerobic glycolytic pathway for ATP formation. And ATP plays a key role in maintaining its shape and determining its viability.
During blood storage, its metabolic cycle must remain intact in vitro for red cells to remain viable post-transfusion survival and effective functioning.
Red blood cells typically contain 2,3 DPG, which lowers the affinity of haemoglobin for oxygen. As such, depletion of 2,3 DPG in stored blood can adversely affect oxygen released by haemoglobin.
Usually, blood cells that survive for the first 24 hours after transfusion will remain viable and circulate in the body for their expected life span.
The maximum allowable storage time, also called shelf life, depends on the requirement of 70 per cent recovery at 24 hours. It means that at least 70 per cent of the transfused red cells should stay in the recipient’s circulation after 24 hours of transfusion.
Anticoagulant-Preservative
The anticoagulant solution is one of the critical factors impacting red cell recovery after blood storage. Some examples are Trisodium citrate–it causes rapid deterioration and often leads to only 50 of the cells remaining viable after one week.
Heparin–also causes rapid deterioration and poses the disadvantage of plasma progressively neutralizing it. Therefore, Heparin is the most unsuitable for storage.
pH
Accumulation of lactic acid leads to a gradual pH fall during blood storage.
Temperature
Although the optimum storage temperature for whole blood and red cells is between 2 to 6 degrees C, an infrequent rise to 10 degrees C is acceptable, especially during transportation.
If you delay the refrigeration, it can lead to 2,3 DPG loss. Platelets and granulocytes function properly when at room temperature.
You can best maintain labile coagulation factors at -30 degrees C or lower. Refrigeration also minimizes the proliferation of bacteria.
Electrolytes and Coagulation Factors
K is the only important electrolyte that can change in stored blood. Usually, there can be a slow but constant leakage of K+ from cells into the surrounding plasma during blood storage.
In severe kidney disease, even a small amount of K+ fluctuation can result in dangerous issues.
Due to a higher K+ content of stored blood, it is advisable to use blood less than five days old for neonatal exchange and top-up transfusion.
Labile coagulation factors, Factors V and VIll, usually lose 50 per cent of their activity within 48 to 72 hours of storage in whole blood stored at 4 degrees C.
Cellular Elements
White cells become non-functional after 24 hrs of storage. They usually lose their phagocytic and bactericidal property within 4 to 6 hours of collection.
However, they do not lose their antigenic property. So white blood cells can sensitize the recipient to produce non-haemolytic febrile transfusion reactions.
While some lymphocytes can remain viable even after three weeks of storage, platelets lose their haemostatic function within 48 hours in whole blood stored at 4 degrees C.
