Pheresis is a blood purification process that consists of:
drawing blood,
separating red cells, plasma, platelets, and cryoprecipitated antihemophilic factor,
isolating the blood component needed to diagnose a suspected abnormality or treat a known disease,
and returning the remaining blood to the donor.
Purpose
Because most of the blood is returned to the donor, pheresis enables an individual to donate more of a specific component. The two main types of pheresis are removal of platelets (plateletpheresis)and removal of plasma (plasmapheresis).
Plateletpheresis
Cancer and cancer treatments can deplete the body's supply of platelets, the colorless particles that stick to the lining of blood vessels and make it possible for blood to clot. Patients who have leukemia or aplastic anemia, are receiving chemotherapy, or undergoing bone marrow transplantation need platelets donated by healthy volunteers to prevent potentially fatal bleeding problems.
Plasmapheresis
Also known as therapeutic plasma exchange, plasmapheresis removes cells from the straw-colored liquid portion of the blood, which contains clotting factors, infection-fighting antibodies, and other proteins. Plasma regulates blood pressure and maintains the body's mineral balance.
Frozen immediately after collection and thawed when needed for transfusion, fresh frozen plasma is sometimes given to control disseminated intravascular coagulation (DIC). A particular problem for cancer patients, this rare condition causes large numbers of blood clots to form, then dissolve.
Leukapheresis
Also known as apheresis, leukapheresis may be used to treat certain leukemia and to collect cells for autologous
stem cell transplant. Performed before chemotherapy is administered, leukapheresis increases the treatment's impact by reducing the number of cancer cells in the bloodstream and permitting the medication to circulate more freely.
Precautions
The American Red Cross will not accept blood or blood products from anyone who is:
unable to meet other requirements established to ensure the safety of donated blood
In general, cancer survivors who were treated surgically or with radiation and have been cancer-free for at least five years may donate blood. Because of the remote danger of contracting cancer as the result of a transfusion, blood donations are not accepted from cancer survivors who have been treated with chemotherapy or hormonal therapy or diagnosed with leukemia or lymphoma.
Throughout the procedure, which lasts between 90 minutes and three hours, the pheresis donor relaxes in a specially contoured chair and watches movies or listens to music. A flexible tube inserted into the donor's arm slowly draws blood into a sophisticated machine (centrifuge) which separates the various blood components, collects whichever component is being donated, and returns the remaining blood through a vein in the donor's other arm. Each pheresis donation is typed and designated for a specific patient.
Inserting the needle can cause mild, momentary discomfort. Some pheresis donors feel a slight tingling around the lips and nose, but this sensation disappears as soon as the procedure is completed.
Plasmapheresis and plateletpheresis can be performed in a hospital or blood collection center. Leukapheresis should be performed in a hospital where bone marrow transplantation is frequently performed.
Preparation
Before undergoing pheresis, a donor should get a good night's sleep, eat a well-balanced meal, and drink plenty of caffeine-free liquids. A donor should not take aspirin within 72 hours or ibuprofen within 24 hours before undergoing plateletpheresis, because these medications would make the platelets less beneficial to the patient receiving the transfusion. The donor's physician will determine whether any other medications should be discontinued in preparation for the procedure.
Aftercare
A pheresis donor may feel tired for a few hours and should not plan on driving home after the procedure. Although the donor may resume normal activities right away, heavy lifting or strenuous exercise should be avoided until the following day.
OTHER
"Adult Chronic Leukemia." American Cancer Society. 2 May 2001. 28 June 2001. <http://www3.cancer.org>.
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