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Definition

The storage lesion refers to red blood cell and biochemical changes that occur during blood storage. These include hemolysis, decreased red blood cell deformability, increased 2,3‐diphosphoglycerate (DPG) levels, increased potassium and lactate, and decreased glucose.

Risk factors

 Long duration of storage. The RBCs continue to break down throughout the storage period.

 Improper collection or storage. Collection into glass bottles inactivates platelets and increases hemolysis. Improper storage solution will not support RBC metabolism and will lead to more rapid RBC breakdown.

Pathogenesis

The morphologic and biochemical changes in stored blood occur, even in storage solutions that provide dextrose and balance pH. Ongoing RBC metabolism and breakdown lead to an increase in potassium and lactate and a decrease in 2,3‐DPG [20]. As the cell membrane deteriorates, increased hemolysis can be detected and hemoglobin microparticles are released. Large‐volume transfusion of stored blood can introduce high levels of potassium and lactate.

As storage time increases, post‐transfusion viability of the RBCs decreases. The post‐transfusion lifespan of equine autologous RBCs stored for 28 days was 59 days, compared to a lifespan of 99 days for fresh, biotinylated blood [21].

Prevention

Fresh whole blood is most often used for equine transfusions, so “storage lesion” (hyperkalemia, hyperlactatemia, decreased 2,3‐DPG) is not usually a concern. When collecting blood intended for storage, use CPDA‐1 storage bags to support RBC viability. Use a dedicated blood bank refrigerator at 4°C.

Diagnosis and monitoring

Stored blood should be discarded if hemolysis is evident, and storage of equine blood beyond 28 days is not recommended. Horses receiving stored blood should be monitored for hemolysis, hyperkalemia, and poor tissue oxygenation, along with other transfusion reactions.

Treatment

There is no specific treatment indicated for animals that receive older units of RBCs. The decrease in 2,3‐DPG is reversible, so the limitations of oxygen delivery should not be long‐lasting. Additional blood transfusion may be needed if RBC viability has been severely compromised by storage.

Expected outcome

The biochemical and functional changes that occur during RBC storage are similar across species. In dogs, age of the stored RBCs is associated with the risk of transfusion‐related hemolysis, but not with fever or mortality [3].