They are given when a person's life is threatened by loss, destruction, or reduced production of blood. Blood transfusions are often needed for accident victims, surgery patients, and people with blood disorders. Transfused blood may come from volunteer donors or from the patient.
Blood is transfused through a vein.
The amount of blood required depends on the amount lost or on the severity of the blood disorder. The patient's pulse, blood pressure, and temperature are measured regularly during the procedure. When there is any sign of reaction to a blood transfusion, the procedure is immediately stopped. A blood reaction usually is not severe. In rare instances, a transfusion reaction can produce shock or kidney failure.