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Q1: Principles and thresholds (2 min)
- What is a restrictive transfusion strategy and what is the red-cell threshold? Transfuse red cells only when Hb is below 70 g/L in most stable adults (below 80 in cardiac and orthopaedic surgery); give one unit then reassess. At least as safe as a liberal strategy (TRICC, FOcus, AABB 2023).
- Why prefer restrictive over liberal? Reduces transfusion reactions, infection, cost and TACO with no loss of benefit; mortality not higher (in some subgroups lower).
- Name the blood components and one indication for each. Red cells (anaemia/haemorrhage), platelets (thrombocytopenia/bleeding, prophylaxis under 10), fresh frozen plasma (coagulopathy, INR over 1.5 with bleeding), cryoprecipitate (fibrinogen under 1.5 g/L), prothrombin complex concentrate (urgent warfarin reversal).
Q2: Acute haemolytic reaction (2 min)
- Describe the clinical features of an acute haemolytic transfusion reaction. Fever, rigors, flank/back pain, hypotension, tachypnoea, haemoglobinuria (dark urine) and DIC bleeding early in the transfusion.
- What is the mechanism? Preformed recipient IgM anti-A/anti-B binds ABO-incompatible donor red cells and activates complement (membrane attack complex), causing intravascular haemolysis.
- What is the commonest underlying cause and how is it prevented? Clerical MISLABELLING (wrong unit to wrong patient) — prevented by rigorous two-person bedside identification checking.
- Immediate management? STOP, maintain IV access with normal saline, aggressive IV fluids for renal perfusion, support blood pressure and coagulopathy, return unit and samples to blood bank.
Q3: TRALI vs TACO (3 min)
- How do TRALI and TACO present? Both cause acute dyspnoea with bilateral pulmonary infiltrates within (usually) 6 hours of transfusion.
- How do you distinguish them? TRALI is non-cardiogenic — hypotension, normal/low filling pressures, no fluid overload. TACO is cardiogenic — hypertension, raised JVP, positive fluid balance, raised BNP.
- Mechanism of TRALI? Donor anti-HLA/anti-neutrophil antibodies bind recipient neutrophils sequestered in pulmonary capillaries; neutrophil activation causes capillary leak.
- Why does management differ? TACO is volume overloaded — give a loop diuretic (furosemide). TRALI is NOT overloaded — diuresis is unhelpful; give oxygen and respiratory support; usually resolves in 48 to 96 hours.
Q4: Other reactions, prevention and special situations (3 min)
- Anaphylaxis on transfusion — what do you suspect? IgA deficiency with anti-IgA antibodies. Treat with IM adrenaline; use washed or IgA-deficient products thereafter.
- Fever and severe rigors during a platelet transfusion? Suspect bacterial contamination — platelets are stored at room temperature. STOP, blood cultures of patient and unit, broad-spectrum IV antibiotics.
- How is TACO prevented in elderly/cardiac patients? Transfuse slowly, one unit at a time over up to 4 hours, with prophylactic furosemide and fluid-balance monitoring.
- What special products are used in immunocompromised patients? Irradiated products (prevent transfusion-associated graft-versus-host disease) and CMV-negative products; leucodepletion is now standard for all.
- A bleeding trauma patient — what is given early? Tranexamic acid within 3 hours (CRASH-2) plus a massive transfusion protocol (RBC:plasma:platelets approximately 1:1:1).