Packed red blood cells Whereas in high-income countries, most blood transfusions are given to people over 65 years of age (up to 76%). In these countries transfusion are most commonly used for supportive care in heart surgery, transplant surgery, massive trauma, and therapy for solid and blood cancers. Due to changes in surgical practices, medical use of blood is now the major use of red blood cells in high-income countries. Blood transfusion is typically recommended when hemoglobin levels reach 70 g/L (7 g/dL) in those who have stable vital signs. For those with heart disease it is recommended at 80g/L (8 g/dL). RBCs are
Red blood cell nuclei, called reticulocytes, subsequently lose all other cellular organelles such as their mitochondria, Golgi apparatus and endoplasmic reticulum. The spleen acts as a reservoir of red blood cells, but this effect is somewhat limited in humans. In some other mammals such as dogs and horses, the spleen sequesters large numbers of red blood cells which are dumped into the blood during times of exertion stress, yielding a higher oxygen transport capacity. A typical human red blood cell has a disk diameter of approximately 6.2–8.2 µm and a thickness at the thickest point of 2–2.5 µm and a minimum thickness in