There are several types of transfusion reactions, which range from mild to life threatening. In the event of a reaction, the transfusion is stopped and the blood bank is notified. Care in collecting and labeling specimens for the blood bank is crucial.
Acute Hemolytic Transfusion Reactions
Acute hemolytic transfusion reactions (AHTR) occur when a patient's anti-A or anti-B antibodies bind to incompatible transfused red cells. These reactions are seen immediately and are almost always the result of errors in labeling of specimens. The transfused cells are lysed, releasing inflammatory mediators.
Symptoms usually begin with an increase in body temperature and pulse rate. Other symptoms may include chills, back or flank pain, nausea and vomiting, dyspnea, flushing, abnormal bleeding, and hypotension. Disseminated intravascular coagulation (DIC), shock, renal failure, and death may ensue. Laboratory findings can include hemoglobinemia and/or hemoglobinuria, an increased serum bilirubin, and a positive direct antibody test. Aggressive fluid resuscitation with normal saline to maintain blood pressure and urine output should be initiated, as well as specific therapies to correct any associated coagulopathy.2
Delayed Hemolytic Transfusion Reactions
Delayed hemolytic transfusion reactions (DHTR) are caused by sensitization to non-ABO antigens from a previous transfusion. The most prominent signs and symptoms are unexplained anemia, jaundice, fever, back pain, and rarely, hemoglobinemia and/or hemoglobinuria. DHTR are detected 3 to 14 days after transfusion, the previously transfused patient's hemoglobin is below expected values with a history of fever and jaundice. No treatment is usually required.2
Febrile Nonhemolytic Transfusion Reactions
Febrile or nonhemolytic transfusion reactions (FNHTR) are benign and self-limiting; they account for the great majority of transfusion reactions and occur most commonly in the multiply transfused patient. Symptoms include fever and chills that may be difficult to distinguish from AHTR; therefore, if the patient is very uncomfortable, the transfusion should be stopped. Antipyretics may be given. FNHTR are caused by recipient antibodies to antigens on donor leukocytes and platelets. There are no laboratory tests available to predict or prevent these reactions; however, the parent or the patient can often give a history of previous FNHTR, allowing intervention with antipyretics prior to transfusion if prior reactions were severe or frequent.2
Allergic Transfusion Reaction
Allergic transfusion reactions are of three types, each with different etiologies.
Urticarial reactions may involve allergens, cytokines, or histamine in stored blood products. The transfusion must be interrupted and the patient watched closely for signs and symptoms of anaphylaxis. An antihistamine such as diphenhydramine (1 mg/kg) should be administered. When the urticaria fades, transfusion can be resumed.
Anaphylactic reactions are severe urticarial reactions that commonly occur in patients with congenital IgA deficiency who have high-titer IgG anti-IgA antibodies. Activation of a complement and chemical mediator cascade precipitates increased vascular permeability, resulting in angioedema, respiratory distress, urticaria, and shock. The transfusion is stopped, epinephrine is administered (0.01 mg/kg 1:1000 subcutaneously), and blood pressure is stabilized with crystalloid and vasopressive agents if necessary.
Transfusion-related acute lung injury (TRALI) occurs when the permeability of the pulmonary microvasculature is acutely increased, which leads to massive pulmonary edema, usually within 6 hours of transfusion. It is thought to be related to the presence of granulocyte antibodies in either the donor product or the recipient although the specific mechanism is still unknown. Therapy consists of rapid and aggressive pulmonary support.4
Complications of Massive Transfusions
Disturbances in coagulation can occur with massive transfusion therapy.5 Table 106-2 summarizes complications that may occur when large amounts of whole blood or PRBCs are given rapidly. Dilutional thrombocytopenia can be seen when 1.5 times the blood volume must be replaced or when there is pre-existing thrombocytopenia or DIC. Each unit of PRBCs contains approximately 3 g of citrate, which will bind ionized calcium. In a healthy patient, the liver will metabolize 3 g of citrate every 5 minutes. At transfusion rates greater than one unit per 5 minutes or with impaired liver function, citrate toxicity occurs leading to hypocalcemia causing tetany or hypotension. Hyperkalemia can occur with rapid transfusion of PRBCs because the concentration of potassium in stored blood increases with storage. Hypokalemia is also common as transfused RBCs begin active metabolism and intracellular reuptake of potassium. Other complications that can occur include hypothermia if a blood warmer is not used, disturbances in acid/base status, and acute respiratory distress syndrome (ARDS).2
TABLE 106-2Complications of Massive Transfusion Therapy ||Download (.pdf) TABLE 106-2 Complications of Massive Transfusion Therapy
Acute respiratory distress syndrome
Donated blood is routinely screened for HIV-1 and -2, HTLV, hepatitis B surface antigen, hepatitis B core antibody (a surrogate marker for non-A, non-B hepatitis), hepatitis C virus, and syphilis. The estimated risk of transmitting HIV through a blood transfusion is 1 in 146,7000 units transfused; hepatitis B, 1 in 282,000 units transfused; and hepatitis C, 1 in 1,149,000 units transfused.2
Bacterial contamination of blood products can occur and accounts for other transfusion reactions and fatalities. Fever, chills, rigor, vomiting, and hypotension present soon after the transfusion is begun. Blood cultures should be sent from the patient and from the blood product. AHTR is in the differential if the patient is receiving RBCs, and samples (blood and first voided urine) should be sent to the blood bank to check for hemolysis.1