The tangible components of blood include plasma, red blood cells, platelets, and white blood cells. Concentrated red blood cells are actually prepared by a method that separates out the plasma and leaves the red blood cells to be called concentrated red blood cells. Concentrated red blood cells contain only anticoagulants and are mainly used clinically for newborns or patients who are allergic to all additives, but the use of concentrated red blood cells is very low nowadays. The actual unit of red blood cell concentrate is about 100-120 ml, which contains all the red blood cells of 200 ml of whole blood, but only about 10% of plasma, and the plasma content is very small, and it only contains anticoagulant, not any additives, so it is only suitable for patients who are allergic to additives.