Storage Lesion: Definition and Examples
Storage lesion refers to the collection of biochemical, biomechanical, and immunologic changes that occur in red blood cells during ex vivo storage, which may affect their viability, function, and clinical efficacy after transfusion.
Definition of Storage Lesion
Storage lesion encompasses the progressive deterioration that occurs in red blood cells (RBCs) when they are stored outside the body. These changes begin immediately after collection and accumulate throughout the storage period 1, 2.
The storage lesion develops due to two primary root causes:
Metabolite accumulation/depletion: As RBCs are stored, they continue to metabolize, leading to depletion of essential substances and accumulation of waste products 2.
Oxidative damage: RBCs are particularly susceptible to oxidative stress during storage, which leads to various biochemical alterations 2.
Examples of Storage Lesions
1. Biochemical Changes
Reduction in 2,3-DPG and ATP levels: During storage, RBCs experience decreased levels of 2,3-diphosphoglycerate (2,3-DPG) and adenosine triphosphate (ATP), which affects oxygen delivery capacity and cellular energy 1, 3.
pH changes: Progressive acidification of the storage medium occurs due to accumulation of lactic acid from anaerobic metabolism 2.
Potassium leakage: Increased extracellular potassium concentration develops as the sodium-potassium pump function deteriorates during storage 3.
2. Biomechanical Changes
Reduced deformability: RBCs become less flexible during storage, which impairs their ability to navigate through the microcirculation 1, 3.
Echinocyte formation: RBCs transform from biconcave discs to spiculated echinocytes with storage, affecting their surface-to-volume ratio and membrane integrity 2.
Microparticle formation: Membrane vesiculation leads to the release of microparticles, reducing the surface area of RBCs and contributing to their reduced deformability 3.
3. Immunologic/Inflammatory Changes
Accumulation of bioactive substances: Pro-inflammatory cytokines, lipids, and other bioreactive substances accumulate in the storage medium 4, 2.
Phosphatidylserine exposure: This membrane phospholipid becomes externalized during storage, potentially triggering recognition and clearance by the reticuloendothelial system after transfusion 3.
Increased adhesiveness: Stored RBCs demonstrate increased adhesion to endothelial cells, which may impair microcirculatory blood flow 2, 3.
Clinical Implications
The clinical significance of storage lesions remains somewhat controversial. While experimental and observational studies suggest potential adverse effects of transfusing older stored blood, randomized controlled trials have shown mixed results 1, 5.
Current evidence indicates:
- Storage lesions may affect post-transfusion RBC survival and function
- Some patients, particularly those with trauma or undergoing cardiac surgery, may be more susceptible to adverse effects from older stored blood 3
- Despite concerns about storage lesions, current guidelines do not recommend selecting RBC units based on storage duration 1
As stated in the 2020 Anaesthesia guidelines: "It is not recommended to select units of red blood cells according to their duration of storage to decrease the morbidity and mortality in critical care patients" 1.
The maximum storage duration for RBCs in most countries is 42 days, with standard practice being to use the oldest compatible units first to optimize inventory management 1.
Human studies suggest that while storage lesions are real phenomena, their clinical impact may be less significant than previously thought, with a recent study showing no statistically significant difference in hemoglobin rise between transfusions of "new" versus "old" blood 5.