Protocol Number: 99-CC-0168
Whole Blood: Whole blood donors have their pulse, blood pressure, and temperature taken and answer questions about their health and medical history. The donor then lies on a recliner or couch. A needle is placed in an arm vein and a unit of blood (about 400 to 500 ml, or 30 tablespoons) is withdrawn into a plastic bag or several tubes. The entire process takes about 10 to 15 minutes. Blood Components: Donors of blood components (white cells, platelets, and plasma) answer questions about their health and medical history and have their pulse, blood pressure and temperature taken. Blood components are collected in a procedure called apheresis, described below. White cell collection is called leukapheresis; platelet collection is called plateletpheresis, and plasma collection is called plasmapheresis. In leukapheresis, whole blood is drawn through a needle in one arm and flows into a cell separator machine, where it is spun very fast to separate the cells. The needed component is collected in a plastic bag in the machine, while the rest of the blood is returned to the donor either through the same needle or through a needle in the other arm. During the procedure, the donor is given a blood thinner called citrate to prevent the blood from clotting while it is in the cell separator. The procedure may last from 1 to 3 hours, depending on how many cells are collected. Only a small fraction of the body's total cells are removed. The body quickly replaces them, and their loss does not affect the donor's health. To collect a particular type of white cell called granulocytes, a substance called hextastarch is added to the citrate to increase the number of cells collected. Granulocyte donors may also be asked to take a steroid the night before the procedure to increase the white cell count in the blood by the time of collection. Plasmapheresis and plateletpheresis are performed the same way as leukapheresis, except that the plasma or platelets are removed and the remaining parts of the blood returned.
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National Institutes of Health Clinical Center
Bethesda, Maryland 20892. Last update: 01/13/2009
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