(A&E)

Overview

• Blood transfusions are usually safe and serious adverse events are uncommon due to extensive screening and pretransfusion testing
• Mediated by interaction of recipient antibodies to foreign antigens contained in blood product
• Acute Reactions → occur within 24 hrs of transfusion.
  • Acute Haemolytic → result of ABO red-cell incompatibility. Caused by clerical error resulting in mistransfusion. Leads to RBC destruction by IgM antibodies.
  • Allergic/Anaphylaxis → hypersensitivity reactions to allergens in the transfused component. Anaphlyaxis common in IgA deficient patients who have anti-IgA antibodies.
  • Febrile Non-Haemolytic Transfusion → immune-mediated. Often the result of sensitization by previous pregnancies or transfusions
  • Transfusion-Related Acute Lung Injury (TRALI) → result of granulocyte activation in the pulmonary vasculature, resulting in increased vascular permeability.
• Delayed Reactions → occur within days to weeks after transfusion.
  • Delayed Haemolytic Transfusion Reactions → non-preventable, result of an anamnestic antibody response to non-ABO red-cell antigents
  • Transfusion-Associated Graft-Versus-Host Disease → mainly in immunodeficient patients, in which transfused white cells react with recipient antigens.
  • Post-Transfusion Purpura → result of prior sensitisation to foreign platelet antigen, usually during pregnancy

Making Diagnosis

Clinical Features:

• Acute Haemolytic → fever, abdominal pain, hypotension
• Allergic/Anaphylaxis → hypotension, dyspnoea, wheezing, angioedema (major), urticaria (minor)
• Febrile Non-Haemolytic Transfusion → fever and chills (otherwise systemically well)
• 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.
• Transfusion Associated Circulatory Overload (excessive rate of transufusion, pre-existing heart failure) → raised JVP, pulmonary oedema and hypertension (KEY DISTINGUISHER FROM TRALI). Tx with IV Furosemide (Loop Diuretic).

Investigations:

• Direct Antiglobulin Test (Direct Coombs Test) ****→ positive result indicates haemolytic transfusion reaction