Packed red blood cells (PRBCs) are a highly concentrated amount of red blood cells that are used in blood transfusions. They are given to patients who have lost a lot of blood, or who are anemic. These cells increase the blood's ability to carry oxygen due to the increased amount of hemoglobin that they provide.
The process for preparing packed red blood cells begins with whole blood. Whole blood contains not only red blood cells, but also the other components of blood, including plasma and platelets. During processing, the red blood cells are filtered out from the rest of the blood’s components. This "packs" the cells and allows them to take up less space.
In special circumstances, PRBCs can be further processed to remove specific components of the blood that may be harmful to somebody receiving a transfusion. One example would be leukocyte reduced blood cells. Removing leukocytes makes the blood safer for those have had immune responses in previous transfusions. The blood can also be cleaned with saline to produce a similar effect, making it safer for those who have had an allergic or other immune-type response.
Packed red blood cells can be irradiated in some cases. This removes lymphocytes, small white blood cells that fight infection, as they can trigger a reaction in people who have a compromised immune system. People who have had a lot of chemotherapy or who have had an organ transplant often benefit from the irradiated cells. Premature infants and people who have congenital immunity issues also receive cells that have been treated in this way.
When transfused into a host, PRBCs can increase the ratio of blood cells in the blood by about 4%. Hemoglobin, the component responsible for carrying oxygen in the blood, is increased by approximately 1 gram to every deciliter of blood. A typical unit of packed red blood cells measures about 220 milliliters, reduced from about 450 milliliters of whole blood.
One advantage of concentrated cells is that they can be stored for a relatively long time. If refrigerated, they can last up to about 42 days. Frozen cells can last ten years if proper storage methods are used.
The main advantage of using PRBCs is that they can treat an issue more specifically. Removing certain components of the blood can also reduce the possibility of side effects. The separate components that are left over after processing can be used to treat other patients, making it a cost effective procedure as well.