Immunologic Transfusion Complications

Question 1

How common is hemolytic transfusion reaction?

Answer 1

Very uncommon due to efficacy of serologic and procedural techniques in place to prevent them.
HTR occurs < 0.1% of units transfused in the US, but they can be life threatening

Question 2

Which is more common fatal acute HTR or infection with HIV?

Answer 2

Fatal acute HTR due to ABO incompatibility is a more frequent adverse outcome of transfusion than infection with HIV or HCV and is more often due to patient or sample misidentification

Question 3

Can transfusion reaction be delayed?

Answer 3

Yes. HTR can be acute, occurring within 24 hours of transfusion, or delayed, in a reaction that appears 5-7 days after the transfusion.

Question 4

What is a HTR mediated by?

Answer 4

HTR is mediated by antibodies directed against antigens on transfused RBCs.
There are hundreds of RBC antigens but only a small portion of these have clinical significance (AB, Rh, and a few other systems)

Question 5

What causes most severe acute HTRs?

Answer 5

Most severe acute HTRs are due to ABO incompatibility. Acute reactions tend to be more severe than delayed and occur in patients who already have antibodies to RBC antigens when they are transfused with RBCs with the target antigens.

Question 6

What other symptoms can present with HTR?

Answer 6

HTR presents with fever
Nausea, vomiting, hypotension, low back pain, and chest pressure may indicate acute hemolysis, which is usually intravascular.

Question 7

How can you differentiate from heoglobinemia and hemoglobinuria?

Answer 7

Hemoglobin released into plasma from lysed RBCs shows as hemoglobinemia (red plasma instead of yellow) and hemoglobinuria (red urine which remains red after centrifugation)

Question 8

Hemolysis may cause?

Answer 8

Disseminated intravascular coagulation (DIC) and hemodynamic instability.

Question 9

What organ is impaired due to direct toxic effects of hemoglobin? How do you support this organ?

Answer 9

Kidneys. Try to preserve renal function with IV hydration and diuretics

Question 10

Name the 2 settings where Delayed HTR can occur.

Answer 10

Patient is exposed to foreign RBC antigens by transfusion and mounts a primary immune response. As antibody increases, hemolysis may occur
Patient re-exposed to an antigen they were previously sensitized to in the past by previous transfusion or pregnancy. This triggers an anamnestic response.

Question 11

What are the clinical signs of delayed HTR?

Answer 11

Clinically only shows a decrease in hemoglobin, a rise in bilirubin, low grade fever, and malaise

Question 12

Is delayed HTR intravascular or extravascular?

Answer 12

extravascular

Question 13

What is a serological transfusion reaction?

Answer 13

When no hemolysis can be detected in a delayed HTR

Question 14

What is the % occurence of allergic reactions to plasma and what causes the reaction typically?

Answer 14

Occur in 1-3% of patients receiving products containing plasma.
Typically a host response to foreign plasma proteins in the donor components

Question 15

What are the typical signs of an allergic transfusion reaction?

Answer 15

Reaction usually consists of hives, pruritus, and erythema, and can be managed with antihistamines and steroids.
Less frequent more serious reactions include bronchospasm, laryngeal edema, GI disturbances (vomiting, diarrhea, cramps), and hypotension

Question 16

IgA deificient patients with IgA antibodies risk an allergic transfusion reaction if exposed to IgA. What can be done to avoid this reaction?

Answer 16

These patients should be given components from IgA deficient donors or store their own components.
Washing packed RBCs removes IgA

Question 17

How common is a Febrile nonhemolytic transfusion reaction (FNHTR)?

Answer 17

One of the most common complications, occurring in 1-3% of patients receiving transfusions of cellular components
More common in multiply transfused patients and with nonleukoreduced cellular components

Question 18

What are the signs of FNHTR?

Answer 18

Presents with fever during or shortly after transfusion that is unlikely to be associated with the patient’s underlying disease.
May also see chills, rigors, discomfort, nausea, and vomiting.
Reactions are usually mild and resolve in 8 hours or less.

Question 19

What is the treatment for FNHTR?

Answer 19

Treatment - antipyretics

Question 20

What is transfusion associated graft vs host disease (TA-GVHD)?

Answer 20

Immunocompetent T lymphocytes present in blood component may engraft in an immunocompetent transfusion recipient, especially if cellular immunity is compromised.
Engrafted T cells mount an immune response to cells in the skin and GI tract and to the cells in the bone marrow, making this potentially lethal.

Question 21

How is TA-GVHD prevented?

Answer 21

Fortunately, T lymphocytes in blood components can be inactivated by exposure to gamma irradiation to prevent this complication

Question 22

Who are the at risk groups for TA-GVHD

Answer 22

At risk patients include those undergoing stem cell transplant, those with hematologic malignancies, low birth weight infants, infants with hemolytic disease of the newborn, and fetuses receiving intrauterine transfusions

Question 23

How is Transfusion related acute lung injury diagnosed (TRALI)?

Answer 23

Patient develops acute respiratory distress, hypoxia, and bilateral infiltrates on chest x-ray, often with fever and hypotension, during or within 6 hours of completion of a transfusion.
There must be no preexisting form of acute lung injury or sepsis, aspiration, or pneumonia to diagnose TRALI

Question 24

What care is given to those who are diagnosed with TRALI?

Answer 24

Most recover completely with supportive care, which usually includes mechanical ventilation, and the infiltrates usually resolve within 2-4 days

Question 25

What causes TRALI and what is the mortality rate?

Answer 25

Attributed to presence of anti-leukocyte antibodies in plasma of donor blood (often from females with history of pregnancy) that react with recipient’s WBCs to form immune complexes that get trapped in pulmonary vasculature leading to alveolar edema.

Mortality 5%

Question 26

What is Posttransfusion purpura.

Answer 26

Rare complication occurring in patients who lack a common platelet antigen and have developed an antibody by exposure through prior transfusion or pregnancy.

When reexposed by transfusion of platelets, patients develop an anamnestic response and become severely thrombocytopenic 7-10 days later.
Patient’s own platelets, which do not have the antigen, are also cleared

Question 27

What is the treatment for posttransfusion purpura?

Answer 27

Treatment is steroids and IV immunoglobulin

Question 28

What is the cause of refractoriness to platelet transfusions

Answer 28

Patients may become sensitized to leukocyte and platelet antigens through transfusion or pregnancy. Other causes of refractoriness include active bleeding, fever, sepsis, splenomegaly, DIC, TTP, ITP

Question 29

What makes it difficult to elevate the platelet count in a patient with refractoriness

Answer 29

Transfused platelets may be cleared rapidly when given to a patient with preformed antibodies to antigens on the platelet membrane

Question 30

Patients with immunologic refractoriness may respond to?

Answer 30

Platelets from donors who lack the antigens or to platelets chosen from platelet crossmatching.