Six hours after receiving two units of packed red cells, a post-operative patient develops acute hypoxaemia and bilateral infiltrates on chest radiograph. The pulmonary artery occlusion pressure is 10 mmHg and B-type natriuretic peptide is normal. Which mechanism best explains this reaction?
- A Recipient antibodies against donor red cell antigens
- B Volume overload from rapid transfusion
- C Donor anti-HLA antibodies causing capillary leak in the recipient lung ✓
- D Bacterial contamination of the unit with endotoxaemia
Correct answer: C. Donor anti-HLA antibodies causing capillary leak in the recipient lung
Explanation
TRALI is defined as new acute lung injury within six hours of transfusion with a normal hydrostatic pressure (PCWP under 18 mmHg). The commonest mechanism is passively transferred donor anti-HLA or anti-neutrophil antibodies binding recipient leucocytes in the pulmonary microvasculature, causing capillary leak. C normal PCWP and normal BNP exclude volume overload, and haemolytic reactions cause fever and haemoglobinuria rather than non-cardiogenic pulmonary oedema.
Reference: Sabiston Textbook of Surgery, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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