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06-15-2006 01:06 AM |
How is this procedure performed?
Before you donate blood, the healthcare professional will check your blood pressure, temperature, and pulse. You will lie down on a bed or cot, then he or she will tighten a wrapping, called a tourniquet, on your upper arm to increase the pressure on the veins in your arm so they will swell. This makes it easier to identify the larger veins and to insert the needle into the vein. The healthcare professional will clean the area where the needle will be inserted with an antiseptic wash, then insert a large needle into the vein. You will feel a slight sting as the needle goes in, but the rest of the procedure should be painless. The blood flows through a tube into a sterile plastic bag that holds around one pint (450 ml) of blood, also called one unit. People usually donate one unit at a time. The average man has 10 to 12 pints of blood in his body, while the average woman has 8 to 9 pints. A small sample of the blood you donate is put aside for testing for infectious diseases. No blood is used until all test results have shown that it is safe. All donated blood is also classified and labeled by type, either A, B, AB, or O, and as RH-positive or RH-negative. This is because donor blood must be matched to the recipient's blood type. The sterile bags, which contain preservatives and an agent that prevents clotting, are kept refrigerated. Whole blood is usable for 42 days.
Some patients may feel light-headed when they first stand up after donating blood. You will be given juice to drink and cookies or crackers to eat to begin replacing fluids and increase your blood sugar levels. You will be told to drink plenty of liquids to replace lost fluids and to avoid strenuous activity for the remainder of the day. You may feel a little sore around the area where the needle was inserted, and their is a slight chance of infection in that area if it wasn't well cleaned before the needle was inserted. Your blood volume will return to normal within hours after donating blood if you follow the guidelines for drinking liquids. It takes several weeks, however, to replace donated blood cells and platelets.
http://www.hmc.psu.edu/healthinfo/b/blooddonation.htm
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