transfusion reaction
An adverse response to a transfusion caused by the presence of foreign antigens, antibodies, or cytokines. There are three basic types of true transfusion reactions and several other complications of transfusion therapy.
Hemolytic reactions occur when ABO-incompatible blood is given; antibodies or complement (or both), coat blood cells, stimulating hemolysis by macrophages and neutrophils. These reactions occur in less than 1% of all blood transfusions. In acute hemolytic reactions, patients develop fever, chills, nausea, flank pain, hypotension, flushing, and hematuria within 20 min after the transfusion has begun. Delayed reactions develop 3 to 14 days later; the patient presents with fever, jaundice, and a decreased hemoglobin level. In rare cases, disseminated intravascular coagulopathy, respiratory distress syndrome, acute renal tubular necrosis, and /or death may occur.
Allergic reactions occur when patients have been sensitized to foreign antigens on proteins in the blood or plasma. A history of allergies is usually present, indicating the patient has developed immunoglobulin E antibodies to allergens. Patients develop itching and hives. Mild allergic reactions can be prevented or treated with antihistamines; the use of washed red blood cells (RBCs), which have fewer antigens, also reduces the risk of allergic reactions. Very rarely, systemic anaphylaxis occurs, as indicated by severe hypotension, and wheezing.
Febrile reactions are the result of cytokine release by leukocytes while the blood was being stored. Antipyretics are used to treat the transient fever that appears; the use of fresh blood and leukocyte-poor RBC transfusion also reduces the risk of a febrile response.
Other problems associated with blood transfusions include circulatory overload (the most common transfusion reaction). Bacterial, viral, and protozoal infections may occasionally be transmitted by transfusions, and some patients may suffer a graft-versus-host reaction after receiving blood products. The ability to screen blood for antibodies to hepatitis and human immunodeficiency virus has decreased the risk of acquiring these diseases through blood transfusion; however, malaria and bacterial infections can still occasionally be transmitted if the donor is asymptomatic. The acute pulmonary edema caused by circulatory overload can be diagnosed by crackles, gurgles, and wheezes on auscultation of the chest, severe difficulty in breathing, frothy sputum, decreased oxygen saturation, and abnormal findings on chest x-rays. Immunosuppressed patients may receive irradiated blood to prevent activation of donor leukocytes and graft-versus-host disease.
Patient Care: Hemolytic blood transfusion reactions are prevented by labeling the patient's blood sample for typing and cross-matching; double-checking the patient's name and identification number at the time of transfusion is essential. Antihistamines and antipyretics may be given to patients with a history of multiple blood transfusions, allergies, or a previous febrile transfusion reaction. Patients at risk for circulatory overload are placed in an upright position before the transfusion is started, and the blood is administered very slowly; packed RBCs create less risk than whole blood but also must be transfused over several hours.
All patients receiving blood transfusions should be monitored for an adverse response. Transfusions should be initiated by infusing 50 mL during the first 15 min to detect and prevent severe reactions. The patient is told to report any symptoms experienced during this initial period. Vital signs including temperature are checked. The flow rate is only increased if the initial infusion is completed without complications. Vital signs and clinical responses continue to be monitored at least every 30 min throughout the transfusion. If a reaction occurs, the infusion is stopped immediately, but an intravenous line is kept patent with saline. A description of the patient's signs or symptoms, and the blood container and tubing, are sent to the blood bank; blood and urine samples are sent to the laboratory for analysis. In many hospitals, a specialty transfusion nurse is assigned to supervise transfusions and educate staff about policies, procedures, and guidelines to optimize transfusion safety.