ICU · Haematology
Acute transfusion reactions: TRALI, TACO, allergic, haemolytic, and septic
Also known as Transfusion reaction · TRALI · Transfusion-related acute lung injury · TACO · Transfusion-associated circulatory overload · Acute haemolytic transfusion reaction · Anaphylactic transfusion reaction
Transfusion reactions range from mild (febrile, allergic) to life-threatening (TRALI, acute haemolytic, anaphylaxis, septic, TACO). CLASSIFICATION by mechanism: (1) IMMUNE: acute haemolytic (ABO mismatch — intravascular haemolysis, catastrophic, STOP immediately), delayed haemolytic (days-weeks), TRALI (donor anti-leucocyte antibodies - acute lung injury within 6h), anaphylactic (IgA deficiency in recipient — severe), febrile non-haemolytic (cytokines), allergic/urticarial (mild). (2) NON-IMMUNE: TACO (volume overload), septic (bacterial contamination of platelets — fever, shock), hyperkalaemia (old RBCs), hypocalcaemia (citrate), hypothermia. KEY ACTION for ANY reaction: STOP transfusion, maintain IV access with normal saline, assess (ABC), send blood unit + samples to blood bank, report. TRALI: new ARDS within 6h of transfusion — manage as ARDS (oxygen, ventilation), diuretics DON'T help (not volume overload). TACO: volume overload — diurese. Acute haemolytic: ABO incompatibility — STOP, fluids, support BP/kidneys, treat DIC. Anaphylactic: adrenaline IM/IV.
Checked against its sources on 9 Oct 2026
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Red flags
- ANY transfusion reaction: STOP the transfusion, keep IV open with saline, assess ABC
- TRALI: ARDS within 6h of transfusion — NOT volume overload (diuretics don't help)
- Acute haemolytic (ABO mismatch): catastrophic — fever, back pain, hypotension, haemoglobinuria
- Anaphylactic (IgA deficiency): severe — IM adrenaline immediately
- Septic (platelets): fever + shock during/shortly after — STOP, cultures, antibiotics
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Meet the patient
A 62-year-old woman, day two after a Whipple, gets fresh frozen plasma for a high INR. Within the hour her SpO2 falls to 86%, she spikes 38.8°C, and her pressure bottoms at 88/52 — and the nurse's hand is already on the clamp.[1]
Now you stand at a three-way fork: TRALI (leak), TACO (load), or anaphylaxis. New hypoxaemia within 6 h of transfusion with a normal heart and a NT-proBNP ratio of 1.5 or less is TRALI by the 2019 consensus redefinition; a raised JVP with positive fluid balance and a NT-proBNP ratio over 1.5 is TACO; hypotension with bronchospasm and urticaria in the first few millilitres is anaphylaxis from IgA deficiency with anti-IgA antibodies.[1][17][18][24]
Transfusion reactions compared
[1]
| Reaction | Timing | Mechanism | Severity | Key features | Treatment |
|---|---|---|---|---|---|
| Febrile non-haemolytic | During/after | Cytokines from donor leucocytes | Mild | Fever, rigors | Antipyretic; may continue |
| Allergic/urticarial | During/after | Plasma protein (mild IgE) | Mild-moderate | Urticaria, itch | Antihistamine; may continue |
| Anaphylactic | Rapidly (mls) | IgA deficiency (anti-IgA) | SEVERE | Hypotension, bronchospasm, urticaria | IM adrenaline, fluids |
| Acute haemolytic (ABO) | During (mls) | ABO incompatibility (IgM/IgG) | CATASTROPHIC | Fever, back pain, hypotension, haemoglobinuria, DIC, AKI | STOP, fluids, support BP/kidneys |
| TRALI | Within 6h | Donor anti-leucocyte Ab | Severe | ARDS (hypoxaemia, bilateral infiltrates) | Oxygen, ventilation (diuretics DON'T help) |
| TACO | During/within 6h | Volume overload | Moderate-severe | Pulmonary oedema, hypertension, JVP raised | Diurese, oxygen |
| Septic (platelets) | During/after | Bacterial contamination | Severe | High fever, rigors, shock | STOP, cultures, antibiotics |
TRALI vs TACO — detailed clinical differentiation
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[17]
[18]
[15]
[19]
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| Parameter | TRALI | TACO |
|---|---|---|
| Underlying mechanism | Donor anti-HLA / anti-HNA antibodies -> recipient neutrophil activation -> pulmonary capillary leak (non-cardiogenic ARDS) | Hydrostatic — transfused volume exceeds cardiac reserve -> cardiogenic pulmonary oedema |
| Onset after transfusion | Within 6 h (usually 1-2 h) | During or within 6 h (often towards end / after) |
| Blood pressure | HYPOTENSION (transient) | HYPERTENSION (raised from baseline) |
| JVP | Low / normal | Raised |
| Fluid balance | Neutral or negative | Markedly positive |
| Temperature | Fever common | Afebrile (usually) |
| Auscultation | Bilateral crackles (ARDS) | Crackles + S3 gallop |
| Echocardiography | Normal LV systolic function | LV dysfunction / diastolic dysfunction / volume overload |
| NT-proBNP | Ratio 1.5 or less; low absolute level | Ratio over 1.5 (post/pre-transfusion); BNP under 300 pg/mL or NT-proBNP under 2000 pg/mL makes TACO unlikely |
| Diuretic response | Not a therapy — treatment is supportive | Good — offloads hydrostatic oedema |
| Chest X-ray | Bilateral infiltrates (ARDS pattern) | Bilateral alveolar infiltrates +/- cardiomegaly |
| Risk factors | Multiparous female donor; recent surgery, sepsis, alcohol misuse, massive transfusion | Heart failure, renal impairment, elderly, infants, rapid/large transfusion, positive fluid balance |
| Treatment | Oxygen / lung-protective ventilation; NO diuretics; vasopressors for shock | Diurese (frusemide), sit upright, oxygen +/- NIV |
| Prevention | Male-predominant plasma donors (OR 0.61); screen donors for anti-HLA/HNA | Restrictive strategy; judicious fluids in CKD / LV dysfunction; consider pre-transfusion furosemide 20 mg IV if 65 or over |
Immediate management of ANY suspected transfusion reaction
[22]
- STOP THE TRANSFUSION — clamp the line (keep the cannula; do not discard the unit or giving set). Do NOT restart until the reaction has been classified: any unexpected symptom during or after transfusion should be treated as a possible transfusion reaction until proven otherwise.[3][22]
- MAINTAIN IV ACCESS + ASSESS ABC — keep the IV cannula patent, assess airway, breathing, circulation and skin, and check vitals frequently. Initial management of an acute reaction is early identification, immediate interruption, early haematology and ICU consultation, and fluid resuscitation as required.[22]
- INVESTIGATE — check patient identity against the unit; return the blood unit and giving set to the blood bank with fresh patient samples: full blood count, renal function, coagulation, direct antiglobulin test and haemolysis markers to exclude immune haemolysis, and blood cultures (patient and unit) if sepsis is possible. Repeat group and crossmatch.[23]
- CLASSIFY THE REACTION + SPECIFIC TREATMENT — (a) MILD (febrile, urticarial): antipyretic and/or antihistamine; restart cautiously only after review and if severe causes are excluded. (b) ANAPHYLAXIS: IM adrenaline 0.5 mg into the thigh plus fluids and oxygen; escalate early.[30] (c) ACUTE HAEMOLYTIC: stop, aggressive IV crystalloid resuscitation, vasopressors for hypotension, and supportive management of DIC and renal injury.[22] (d) TRALI: oxygen and lung-protective ventilation — TRALI is permeability oedema, not volume overload, so treatment is supportive.[17][28] (e) TACO: sit upright, oxygen, and offload volume with an IV loop diuretic.[17][19] (f) SEPTIC: stop, culture unit and patient, immediate broad-spectrum antibiotics and vasopressors.[5]
- DOCUMENT + REPORT — every reaction, mild or severe, must be reported to the blood bank and the haemovigilance system; any symptom arising within 24 h of a transfusion should be considered a reaction and referred for haemovigilance reporting, and all cases of post-transfusion pulmonary oedema should be reported so they can be classified (TRALI Type I/II, ARDS, TACO, indistinguishable).[1][21][22]
- PREVENTION — (a) avoid unnecessary transfusion and use a restrictive strategy: transfuse stable hospitalised adults at haemoglobin under 7 g/dL (AABB 2023; TRICC).[6][7] (b) leucoreduction, plasma reduction and patient blood management programmes mitigate noninfectious events.[23] (c) male-predominant plasma sourcing reduces TRALI.[15] (d) irradiated cellular products for at-risk recipients prevent TA-GVHD — leucoreduction alone is insufficient.[25] (e) after an anti-IgA-type reaction, plan future products with the transfusion service.[24]
TRALI management — step-by-step pathway
- STOP THE TRANSFUSION IMMEDIATELY — clamp the line; keep the unit and giving set for blood-bank investigation and report the reaction. Maintain IV access.[22]
- RECOGNISE — TRALI and TACO both present as acute pulmonary oedema within 6 h of transfusion; TRALI is permeability (non-cardiogenic) oedema. Under the 2019 consensus redefinition, TRALI is Type I (no ARDS risk factor) or Type II (an ARDS risk factor or mild existing ARDS is present), and the term "possible TRALI" has been dropped. A post/pre-transfusion NT-proBNP ratio of 1.5 or less, with low absolute levels, argues for TRALI over TACO.[17][1][18]
- SUPPORTIVE — OXYGEN FIRST — escalate oxygen, HFNC and NIV, then intubation as hypoxaemia dictates. Ventilate lung-protectively: tidal volume 6 mL/kg predicted body weight with plateau pressure 30 cmH2O or less — the injured lung behaves like ARDS from any cause, and this strategy reduced mortality in ARDS (31.0% vs 39.8%).[27]
- DO NOT GIVE DIURETICS AS DEFINITIVE THERAPY — TRALI is not hydrostatic oedema; treatment is supportive and no specific therapy is proven.[17][28][29]
- MANAGE SHOCK — treat hypotension with cautious crystalloid resuscitation and vasopressors as required.[22]
- INVESTIGATE + REPORT — send donor and recipient samples for anti-HLA / anti-HNA antibody testing, remembering that TRALI remains a clinical diagnosis and does not require detection of white-cell antibodies; send NT-proBNP and obtain echocardiography to separate TACO; exclude haemolysis (DAT, FBC, coagulation); report every case to the transfusion service for classification.[1][18]
- RECOVERY — care is supportive; specific therapies are lacking and TRALI remains a leading cause of transfusion-associated death, so severity should never be under-estimated.[28][29]
- PREVENT RECURRENCE — source future plasma and apheresis platelets from low-risk donors (low-risk donor strategies reduced TRALI with OR 0.61, 95% CI 0.42-0.88). Report so the implicated donation can be quarantined, tested and managed by the blood service.[15][12][28][1]
TACO management — step-by-step pathway
- STOP THE TRANSFUSION — clamp the line, keep the unit and giving set, notify the blood bank and report to haemovigilance: TACO is among the leading causes of transfusion-related morbidity and mortality and is under-recognised.[20][21]
- RECOGNISE — acute dyspnoea with hydrostatic (cardiogenic) pulmonary oedema during or within 6 h of transfusion, typically with positive fluid balance and cardiorenal risk factors. Biomarkers support the diagnosis: a post/pre-transfusion NT-proBNP ratio over 1.5 supports TACO, while post-transfusion BNP under 300 pg/mL or NT-proBNP under 2000 pg/mL (within 24 h of the reaction) make TACO unlikely — though specificity is poor in the critically ill.[17][18]
- SIT UPRIGHT + OXYGEN — position upright and give supplemental oxygen, escalating to HFNC or NIV for refractory hypoxaemia, with early ICU involvement.[22]
- DIURESE — IV LOOP DIURETIC — offload the transfused volume with an IV loop diuretic. Prevention has been prospectively studied: a pilot randomised trial in inpatients aged 65 or older used pre-transfusion furosemide 20 mg IV for single-unit transfusions.[19]
- REDUCE CIRCULATORY LOAD — stop non-essential IV fluids and review total intake; efforts to minimise TACO should focus on judicious use of transfusion and non-sanguineous fluids, particularly in patients with chronic kidney disease, left ventricular dysfunction, chronic beta-blockade and after emergency surgery.[2]
- MONITOR — continuous SpO2 and frequent blood pressure, JVP and urine-output assessment; repeat NT-proBNP to track resolution.[18]
- REPORT + PREVENT RECURRENCE — TACO is a reportable reaction. For future transfusions: avoid unnecessary transfusion (restrictive strategy — stable adults at haemoglobin under 7 g/dL), minimise concomitant crystalloid in at-risk patients, and consider pre-transfusion furosemide 20 mg IV in patients aged 65 or over (pilot evidence only).[22][6][2][19]
References30ShowHide
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- [19]Pendergrast J, et al. Can furosemide prevent transfusion-associated circulatory overload? Results of a pilot, double-blind, randomized controlled trial Transfusion, 2019.PMID 30924166
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