1) Red blood cells undergo numerous biochemical changes during storage known as the "storage lesion" that may impair their function. These include loss of nitric oxide, potassium leakage into plasma, decreased 2,3-DPG and pH. 2) Retrospective studies show patients receiving older stored blood have worse outcomes like increased mortality, morbidity and organ dysfunction. 3) A case study describes a patient who developed hyperkalemia and cardiac arrest after receiving very old stored blood, highlighting the risks of potassium leakage from aged red blood cells.