EM SAQs · Anaemia and transfusion
Anaemia, transfusion and transfusion reactions
An ACEM-style SAQ on the restrictive transfusion threshold in ischaemic heart disease, the pre-transfusion bundle and the recognition of TACO versus TRALI, with a model answer, common errors and examiner notes.
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Model answer
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This is symptomatic severe anaemia on a background of an upper gastrointestinal bleed, with ischaemic heart disease as the key modifier of the transfusion strategy.[1]
(a) Transfusion strategy — restrictive, FOCUS-style. FOCUS randomised high-cardiovascular-risk hip-fracture patients to a liberal haemoglobin threshold of 10 g/dL versus a restrictive strategy (symptoms of anaemia or haemoglobin below 8 g/dL). The primary outcome was 35.2 versus 34.7 per cent (odds ratio 1.01) — no benefit of the liberal arm.[1] ED teaching often uses 80 g/L as that restrictive arm, not a licence to transfuse to 100 g/L. Give one unit at a time and recheck.
(b) The pre-transfusion steps and monitoring. Group and screen to establish the ABO and the RhD group and to detect clinically significant antibodies; crossmatch to confirm compatibility. Obtain informed consent — the indication, the common risks (febrile, allergic, TACO) and the rare serious risks (TRALI, haemolytic, infection), and the option to decline. Perform the bedside two-identifier check — the patient's name and date of birth against the unit label, the unit number, the blood group and the expiry; inspect the unit. This check prevents the acute haemolytic reaction, which haemovigilance traces to process error. Give the unit slowly in this elderly cardiac patient and consider a diuretic: TACO risk rises with transfusion speed and volume and with cardiorenal comorbidity.[3] Monitor during the unit; acute reactions occur during or within 24 hours.
(c) The most likely diagnosis is TACO — transfusion-associated circulatory overload. Dyspnoea, tachypnoea, hypoxia, hypertension and bilateral crackles during the unit is classic TACO; hypertension and fluid overload separate it from TRALI. TACO is the leading cause of reaction-related death.[3] Immediate management: STOP the transfusion and keep the IV line open with saline; sit the patient upright; give high-flow oxygen; give a loop diuretic; consider non-invasive ventilation if hypoxia does not resolve; return the unit and fresh samples to the blood bank; report to haemovigilance. The one reaction to distinguish it from is TRALI — post-transfusion pulmonary oedema without overload, often hypotensive; Vlaar 2019 requires reporting so TACO and TRALI can be classified.[2]
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- [1]Carson JL, Terrin ML, Noveck H, et al. Liberal or restrictive transfusion in high-risk patients after hip surgery (FOCUS). New England Journal of Medicine, 2011.PMID 22168590
- [2]Vlaar APJ, Juffermans NP, Bux J, et al. A consensus redefinition of transfusion-related acute lung injury. Transfusion, 2019.PMID 30993745
- [3]Soni L, Saeed S, Cserti-Gazdewich C, McVey MJ. Mortality-associated risk factors for transfusion-associated circulatory overload. Vox Sang, 2024.PMID 38872390