Special Blood Donation and Transfusion Procedures
In plateletpheresis, a donor gives only platelets rather than whole blood. Whole blood is drawn from the donor, and a machine that separates the blood into its components selectively removes the platelets and returns the rest of the blood to the donor. Because donors get most of their blood back, they can safely give 8 to 10 times as many platelets during one of these procedures as they would give in a single donation of whole blood. They can also give platelets more often, once every 3 days (but no more than 24 donations during a year). Collecting platelets from a donor takes about 1 to 2 hours, compared with collecting whole blood, which takes about 10 minutes.
In the so-called double red blood cell donation, a person donates twice as many red blood cells as with a single donation of whole blood. This double donation is possible because the person gives only red blood cells rather than whole blood. Whole blood is drawn from the donor, and a machine that separates the blood into its components selectively removes the red blood cells and returns the rest of the blood components (platelets and plasma) to the donor. Some fluid is also given to the donor intravenously because otherwise, the donor's blood pressure could become low enough to cause symptoms, such as light-headedness or loss of consciousness. After double red blood cell donation, people may be less able to exercise vigorously for a few days. Double red blood cell donation can be done as often as once every 112 days (every 16 weeks). Some experts recommend that people take iron supplements after double red cell donation so that their body can replace the donated red blood cells more rapidly.
In an autologous transfusion, donors are recipients of their own blood. For example, in the weeks before undergoing elective surgery, a person may donate several units of blood to be transfused if needed during or after the surgical procedure. The person takes iron pills after donating the blood to help the body replenish the lost blood cells before surgery. Also, during some types of surgery and in certain kinds of injuries, blood that is lost can be collected, washed, and immediately given back to the person (intraoperative blood salvage). An autologous transfusion eliminates the risks of incompatibility and blood-borne disease (unless the wrong blood is given by mistake). However, doctors do not use this technique as often as standard transfusion because the general blood supply is very safe due to rigorous donor screening and testing. In addition, older people may not tolerate donating blood before surgery because they are more likely to have side effects during donation such as low blood pressure and fainting. Older people are also more likely to have fewer blood cells than normal (a low blood count) to begin with. Also, autologous transfusion is more expensive than standard transfusion.
Family members or friends can donate blood specifically for one another if the recipient's and donor's blood types and Rh factors are compatible. For some recipients, knowing who donated the blood is comforting, although a donation from a family member or friend is not necessarily safer than one from an unrelated person. Blood from a family member is tested, as are all blood samples, and then treated with radiation to prevent graft-versus-host disease, which, although rare, occurs more often when the recipient and donor are related.
In hematopoietic stem cell apheresis, a donor gives only hematopoietic stem cells (undifferentiated cells that can develop into any type of blood cell) rather than whole blood. Before the donation procedure, the donor receives an injection of a special type of protein (growth factor) that stimulates the bone marrow to release stem cells into the bloodstream. Whole blood is drawn from the donor, and a machine that separates the blood into its components selectively removes the hematopoietic stem cells and returns the rest of the blood to the donor. Stem cell donors and recipients must have compatible leukocyte types (human leukocyte antigen, or HLA), a type of protein found on certain cells, rather than blood type. Hematopoietic stem cells are sometimes used to treat people with leukemia, lymphoma, or other cancers of the blood. This procedure is called stem cell transplantation. The recipient's own stem cells can be obtained, or donated stem cells can be given.