Known Changes in Stored Blood
The known change occurring in stored blood is increased H+ (option A), which leads to acidification of the stored blood.
Biochemical Changes in Stored Blood
When blood is stored, several biochemical changes occur that affect its quality and functionality. These changes, collectively known as the "storage lesion," include:
Primary Change: Increased H+ (Acidosis)
- Blood stored in blood banks undergoes progressive acidification due to anaerobic glycolysis 1
- During storage, red blood cells continue metabolic processes that produce lactic acid, leading to increased H+ concentration and decreased pH 2
- The pH of stored blood suspensions in traditional storage media is typically around 7.25 at 4°C, which is suboptimal for red cell metabolism 2
Other Important Storage Lesions
- Reduction in 2,3-DPG (2,3-diphosphoglycerate), not an increase as suggested in option B 1
- Altered red cell deformability (increased fragility, not decreased as suggested in option C) 1
- Increased (not decreased) potassium levels due to leakage from red cells 1
Mechanism of Acidification in Stored Blood
The acidification process in stored blood occurs through the following mechanisms:
- Red blood cells continue glycolysis during storage, producing lactate and H+ as end products 2
- Without adequate oxygen, anaerobic metabolism predominates
- The rate of H+ production exceeds the buffering capacity of the storage medium
- Temperature affects the pH optimum of glycolysis, with current storage conditions (4°C) being suboptimal 2
Clinical Implications of Storage Lesions
The storage-related changes have important clinical implications:
- Decreased oxygen delivery capacity due to reduced 2,3-DPG levels 1
- Increased risk of hyperkalemia when transfusing large volumes of stored blood
- Potential for transfusion-related acidosis in massive transfusion scenarios
- Reduced post-transfusion viability of red blood cells 1
Distinguishing Between Options
- Option A (Increased H+) is correct - Stored blood undergoes acidification due to ongoing anaerobic glycolysis
- Option B (Increased 2,3-DPG) is incorrect - 2,3-DPG actually decreases during storage 1
- Option C (Decreased red cell fragility) is incorrect - Red cell fragility increases during storage 1
- Option D (Decreased K+) is incorrect - K+ levels increase in stored blood due to leakage from red cells 1
The evidence clearly demonstrates that increased H+ concentration is a known and significant change occurring in stored blood, making option A the correct answer.