Transfusion Health Article

Risks for recipients

A number of precautions must be taken for transfusion recipients. Donated blood must be matched with the recipient's blood type, as incompatible blood types can cause a serious adverse reaction (transfusion reaction). Blood is introduced slowly by gravity flow directly into the veins (intravenous infusion) so that medical personnel can observe the patient for signs of adverse reactions. People who have received many transfusions may develop an immune response to some factors in foreign blood cells (see below). This immune reaction must be evaluated before the patient is given new blood.

Adverse reactions to mismatched blood (transfusion reaction) is a major risk of blood transfusion. Transfusion reaction occurs when antibodies in the recipient's blood react to foreign blood cells introduced by the transfusion. The antibodies bind to the foreign cells and destroy them. This destruction is called a hemolytic reaction. In addition, a transfusion reaction may also cause a hypersensitivity of the immune system that may in turn result in tissue damage within the patient's body. The patient may also have an allergic reaction to mismatched blood.

The first symptoms of transfusion reaction are a feeling of general discomfort and anxiety. Breathing difficulties, flushing, and a sense of pressure in the chest or back pain may also be present. Evidence of a hemolytic reaction can be seen in the urine, which will be colored from the hemoglobin leaking from the destroyed red blood cells. Severe hemolytic reactions are occasionally fatal. Reactions to mismatches of minor factors are milder. These symptoms include itchiness, dizziness, fever, headache, rash, and swelling. Sometimes the patient will experience breathing difficulties and muscle spasms. Most adverse reactions from mismatched blood are not life-threatening.

Infectious diseases can also be transmitted through donated blood and constitute another major risk of blood transfusion. The infectious diseases most often acquired from blood transfusion in the United States are hepatitis and HIV.

Patients who are given too much blood can develop high blood pressure, a concern for people who have heart disease. Very rarely, an air embolism is created when air is introduced into a patient's veins through the tubing used for intravenous infusion. The danger of embolism is greatest when infusion is begun or ended. Care must be taken to ensure that all air is bled out of the tubing before infusion begins, and that the infusion is stopped before air can enter the patient's blood system.

Normal results

Most individuals will feel only a slight sting from the needle used during the blood donation process, and will not experience any side effects after the procedure is over. Plasma is regenerated by the body within 24 hours, and red blood cells within a few weeks. Patients who receive a blood transfusion will usually experience mild or no side effects.

Morbidity and mortality rates

The risk of acquiring an infectious disease from a blood transfusion is very low. The risk of HIV transmission is one in 450,000 to 660,000 units of blood; hepatitis B virus (HBV), one in 137,000 units; and hepatitis C virus (HCV), one in 1,000,000 units. Bacterial contamination (a cause of infection) is identified in one in 4,200 transfusions. Approximately one in 25,000 individuals who receive a blood transfusion will develop a hemolytic reaction; the risk of a fatal hemolytic reaction is one in 160,000.

Alternatives

There are several alternatives to blood transfusion as of 2003. These include:

• Volume expanders. Certain fluids (saline, Ringer's lactate solution, dextran, etc.) may be used to increase the patient's blood volume without adding additional blood cells.
• Blood substitutes. Much research is currently being done into compounds that can replace some or all of the functions of blood components. One such compound, called HBOC-201 or Hemopure, is hemoglobin derived from bovine (cow) blood. Hemopure shows promise as a substitute for red blood cell transfusion.
• Bloodless surgery. It may be possible to avoid excessive blood loss through careful planning prior to surgery. Specialized instruments can minimize the amount of blood lost during a procedure. It is also possible to collect some of the blood lost during surgery and reinfuse it into the patient at the end of the operation.

See also Blood donation and registry; Bloodless surgery.

BOOKS

Berkow, Robert, ed. Merck Manual of Medical Information. Whitehouse Station, NJ: Merck Research Laboratories, 1997.

Lefevre, Patrice, and Pascale Poullin. "Current Information on Risks of Allogenic Blood Transfusion." In Transfusion Medicine and Alternatives to Blood Transfusion. Chatillon, France: Network for Advancement of Transfusion Alternatives, 2000.