Transfusion Reactions

Question 1

What is meant by “transfusion reaction”?

Answer 1

Reaction mediated by interaction of recipient antibodies to foreign antigens contained in blood product
- Blood transfusions are usually safe and serious adverse events are uncommon due to extensive screening and pretransfusion testing

Question 2

What are the different types of transfusion reactions you can have?

Answer 2

1. Acute Reactions → occur within 24 hrs of transfusion.
2. Delayed Reactions → occur within days to weeks after transfusion.

Question 3

What are some causes of acute reactions?

Answer 3

Acute Reactions → occur within 24 hrs of transfusion:
1. Acute Haemolytic →
Caused by giving an incompatible blood bag to a patient. Result of ABO red-cell incompatibility. Caused by clerical error resulting in mis transfusion. Leads to RBC destruction by IgM antibodies.
2. Allergic/Anaphylaxis → hypersensitivity reactions to allergens in the transfused component. Anaphylaxis common in IgA deficient patients who have anti-IgA antibodies.
3. Febrile Non-Haemolytic Transfusion → immune-mediated. Often the result of sensitization by previous pregnancies or transfusions
4. Transfusion-Related Acute Lung Injury (TRALI) → result of granulocyte activation in the pulmonary vasculature, resulting in increased vascular permeability.
5. Transfusion-associated circulatory overload (TACO)
Presents with fluid overload

Question 4

What are some causes of delayed reactions?

Answer 4

Delayed Reactions → occur within days to weeks after transfusion.
1. Delayed Haemolytic Transfusion Reactions → Caused by an exaggerated response to a foreign red cell antigen that the patient has been exposed to before
2. Transfusion-Associated Graft-Versus-Host Disease: caused by donor blood lymphocytes attacking the recipient’s body → mainly in immunodeficient patients, in which transfused white cells react with recipient antigens.
3. Post-Transfusion Purpura → result of prior sensitisation to foreign platelet antigen, usually during pregnancy
4. Iron overload:
Iron overload usually becomes an issue after 20 units have been given or if serum ferritin rises above 1000 µg/l

Question 5

What are the risk factors for transfusion reactions?

Answer 5

• ABO incompatibility (unusual, and typically results from clerical error), - pregnancy or transfusion (associated with sensitisation to antigens predisposing to future reactions)
• transplantation and immunocompromised status (associated with graft-versus-host disease)
• IgA deficiency (associated with anaphylactoid reaction)
• history of transfusion reaction. 

Question 6

What are the presenting symptoms of transfusion reactions?

Answer 6

1. Acute Haemolytic → fever, abdominal pain, hypotension
2. Allergic/Anaphylaxis → hypotension, dyspnoea, wheezing, angioedema (major), urticaria (minor)
3. Febrile Non-Haemolytic Transfusion → fever and chills (otherwise systemically well)
4. TRALI (transfusion related acute lung injury) → hypoxia, pulmonary infiltrates (pulmonary oedema) on CXR, fever, hypotension. Causes dyspnoea and cough, may lead to ARDS. ‘White out’ on CXR. Tx with furosemide.
5. Transfusion Associated Circulatory Overload (excessive rate of transfusion, pre-existing heart failure) → raised JVP, pulmonary oedema and hypertension (KEY DISTINGUISHER FROM TRALI). Tx with IV Furosemide (Loop Diuretic).

Question 7

What investigations are used to diagnose/ monitor transfusion reactions?

Answer 7

1. Direct Antiglobulin Test (Direct Coombs Test) → positive result indicates haemolytic transfusion reaction
2. Repeat ABO Testing

Question 8

How are transfusion reactions managed?

Answer 8

1. Acute Haemolytic → stop transfusion and fluid resuscitation
2. Major Allergic/Anaphylactic Reaction → stop transfusion and give IM adrenaline (if anaphylaxis)
3. Minor Allergic Reaction (ie. urticaria without anaphylaxis) → temporarily stop transfusion + antihistamine (chlorphenamine) and hydrocortisone
4. Febrile Non-Haemolytic → slow transfusion + antipyretic (paracetamol)
5. Transfusion-related acute lung injury (TRALI) → stop the transfusion, give saline, treat ARDS and give supplementary oxygen as needed
6. Transfusion-associated circulatory overload (TACO) → Slow the transfusion, give furosemide and supplementary oxygen as needed