What Is a Blood Transfusion?

A blood transfusion is used when a patient is in need of blood, either because of some form of blood loss due to trauma or surgery, or to treat severe blood diseases such as hemophilia or sickle-cell disease. Blood transfusions used to be done with whole blood. The modern medical community rarely uses whole blood today, instead specific components are used.

History

• In the 17th century, William Harvey began experimenting with the circulation of blood and was able to successfully transfuse blood in animals. However, when the practice was extended to humans, the consequences were frequently fatal. Dr. Jean-Baptiste Denys, King Louis XIV's physician, successfully transfused sheep blood into a 15-year-old boy. Richard Lower preformed a similar transfusion in front of a meeting of the Royal Society in 1667. Dr. James Blundell preformed the first successful blood transfusion of human blood, between a man and his wife in 1818. In the 1910s, it was discovered that blood could be stored, instead of using direct transfusion. Blood banks became popular during World War I. Eventually, blood types became more understood, and the modern system of blood banks arose. Later developments prompted the separation of blood into blood plasma and red blood cells.

Considerations

• Early blood transfusions were plagued with problems, most significantly, the immune system's tendency to attack the donor blood when not compatible. Blood has different types, relating to the inherited antigenic substances on the surface of the red blood cells, and it was common before compatibility was understood for some transfusions to be remarkably successful (when it so happened that the blood was compatible), while others to end in complete failure. Beyond the known types of A, B, AB, and O, the Rh factor (positive or negative) must be considered, as well as other minor red cell antigens.

Procedure

• Donor units of blood are kept refrigerated, and the transfusion must begin within one half hour after taken into room temperature. A cannula or small hollow tube (intravenous catheter) is used to pump blood into the arm, typically, and is taped in place. One unit of blood is 500 mL, and is given over the span of four hours. Occasionally, antihistamines and/or acetaminophen are given to the patient to prevent allergic reactions.

Benefits

• In almost every situation, the benefits of blood transfusion outweigh the risks. If a doctor advises you to get a blood transfusion, it means that he has decided that the risk to your health from the transfusion is outweighed by the possible benefits. These types of judgement calls are made everyday by health professionals.

Warning

• There are risks in receiving a transfusion, even in modern science when compatibility issues are no longer present. The body can have mild reactions to blood transfusions, such as a fever, chills, headache, backache, chest pain, tachycardia, and hypo-tension. Also, despite blood bank's efforts to eliminate contaminated blood from their banks, there are still small risks of receiving bacteria or viral infections from transfused blood. However, these risks are small (1 in 250,000 transfused units for hepatitis B, for example). There also are risks that clerical error might result in a transfusion reaction by being given the wrong type of blood. However, this is becoming less common as redundancy has been built into blood transfusion matching processes specifically to combat these clerical mistakes.