The word apheresis is derived from the Greek work “Aphaerisis” meaning “to take away”. Apheresis, an increasingly common procedure, is the process of removing a specific component of the blood, such as platelets, and returning the remaining components, such as red blood cells and plasma, to the donor. This process allows more of one particular part of the blood to be collected than could be separated from a unit of whole blood. Apheresis is also performed to collect red blood cells, plasma (liquid part of the blood), and granulocytes (white blood cells).
The apheresis donation procedure takes longer than that for whole blood donation. A whole blood donation takes about 10–15 minutes to collect the blood, while an apheresis donation may take about one to two hours.
When you come to donate a unit of blood, that unit is not kept in its whole blood form. The unit is centrifuged at high speeds to separate the constituent components from each other. Since red blood cells are the heaviest, they sink to the bottom of the bag. The platelet rich plasma and cryoprecipitate factors settle near the middle of the bag. Each of these components are separated into different bags for treatment as follows:
One unit of whole blood can help save as many three lives.
It is difficult to put an exact figure on each type of procedure or illness, but listed below are general estimates for the top blood using events:
After blood has been drawn, it is tested for ABO group (blood type) and Rh type (positive or negative), as well as for any unexpected red blood cell antibodies that may cause problems in a recipient. Screening tests also are performed for evidence of donor infection with hepatitis B and C viruses, human immunodeficiency viruses HIV-1 and HIV-2, human T-lymphotropic viruses HTLV-I and HTLV-II, syphilis and West Nile Virus (WNV).
The specific tests currently performed are listed below:
There are two systems that make up blood type, ABO and Rh. All people belong to one of four inherited blood groups: A, B, AB or O. The letters A and B refer to the kind of antigens that are found on an individual’s red blood cells. An antigen is a protein or carbohydrate on the red cell that triggers an immune response, such as the formation of antibodies. There are four blood types in the ABO system:
People also have an inherited antigen on their red blood cells known as Rh or D antigen. When the D antigen is present, a person’s blood is designated Rh positive. When D antigen is missing, the blood type is designated Rh negative. In general, Rh negative is given to Rh negative patients and Rh positive blood to Rh positive patients.