Transfusion Reactions
Recognize, classify, and manage the full spectrum of transfusion reactions. TRALI vs TACO is a board favorite. Stop the transfusion first, ask questions later.
Overview
Transfusion Reaction Types
| Type | Timing | Key Features | Treatment |
|---|---|---|---|
| Acute Hemolytic | Minutes | Fever, flank pain, dark urine, hypotension, DIC | STOP transfusion, NS bolus, send blood bank sample |
| Febrile Non-Hemolytic (FNHTR) | 1–6h | Fever, chills, NO hemolysis | Acetaminophen, slow rate. Most common reaction |
| Allergic (mild) | Min–hours | Urticaria, pruritus, NO hemodynamic instability | Diphenhydramine, can restart slowly |
| Anaphylactic | Minutes | Hypotension, bronchospasm, angioedema (often IgA deficient) | STOP, IM epinephrine |
| TRALI | 2–6h | Acute hypoxemia, bilateral infiltrates, NO volume overload | Supportive (lung-protective vent), resolves 48–72h. Leading cause of transfusion death |
| TACO | 1–6h | Dyspnea, HTN, JVD, pulmonary edema, elevated BNP | Diuresis (furosemide), O2, slow future transfusions |
| Delayed Hemolytic | 3–14 days | Falling Hgb, jaundice, positive DAT | Usually mild, supportive |
TRALI vs TACO (Board Favorite)
| Feature | TRALI | TACO |
|---|---|---|
| BNP | Low / normal | Elevated |
| CVP / JVD | Normal | Elevated |
| BP | Hypotension | Hypertension |
| CXR | Bilateral infiltrates (like ARDS) | Pulmonary edema, effusions |
| Diuretics | No response | Responds |
STOP the transfusion for ANY suspected reaction. Send the bag and a new blood sample to blood bank. Clerical error (wrong blood to wrong patient) is the #1 cause of fatal acute hemolytic reactions.
Delayed Transfusion Reactions
| Type | Timing | Mechanism | Management |
|---|---|---|---|
| Delayed Hemolytic (DHTR) | 3-14 days | Anamnestic antibody response to minor RBC antigens (Kidd, Duffy, Kell) | Supportive. Future: antigen-negative units. Tormey & Stack, Immunohematology 2009 |
| Transfusion-Associated GVHD | 4-30 days | Donor T-cells attack immunocompromised recipient. Mortality >90% | Prevention: irradiated products for at-risk patients (HCT recipients, congenital immunodeficiency, Hodgkin lymphoma) |
| Post-Transfusion Purpura (PTP) | 5-12 days | Anti-HPA-1a antibodies cause severe thrombocytopenia | IVIG 1 g/kg x 2 days. Platelet transfusion usually ineffective. Mueller-Eckhardt, Lancet 1989 |
| Iron Overload | Chronic (>20 units) | Each pRBC unit contains ~250 mg iron. No excretion mechanism | Monitor ferritin. Chelation with deferasirox when ferritin >1000. Target organs: liver, heart, endocrine |
| Transfusion-Transmitted Infection | Variable | Bacterial contamination (platelets > RBCs), viral (rare with NAT screening) | Cultures, targeted antibiotics/antivirals. Dodd, Transfusion 2012 |
Special Product Modifications
| Modification | What It Does | Indication |
|---|---|---|
| Leukoreduction | Removes WBCs (to <5 x 106) | Prevents FNHTR, CMV transmission, HLA alloimmunization. Universal in most US blood banks Trial of Universal Leukoreduction, NEJM 2003 |
| Irradiation | Prevents donor T-cell proliferation | Prevents TA-GVHD: HCT recipients, Hodgkin lymphoma, fludarabine therapy, congenital immunodeficiency, directed donations from relatives |
| Washed | Removes plasma proteins (IgA, complement) | IgA-deficient patients with anti-IgA antibodies, severe allergic reactions, neonatal transfusions |
| CMV-negative | From CMV-seronegative donors | Pregnancy, neonates, CMV-negative transplant recipients. Leukoreduction is an acceptable alternative ("CMV-safe") |
| Volume-reduced | Concentrates product by removing supernatant | Patients at risk for TACO (CHF, renal failure, neonates). Slower infusion rate also helps |
AABB Guideline: Carson et al, AABB Clinical Practice Guidelines, JAMA 2016 Use restrictive transfusion threshold (Hgb <7 g/dL) in hemodynamically stable adults. Liberal transfusion (Hgb <10) does not improve outcomes and increases transfusion reaction risk.
Workup
Workup
- STOP transfusion, keep IV access
- Send blood bank sample: repeat type & screen, DAT, visual hemolysis check
- CBC, BMP, LDH, haptoglobin, bilirubin, UA (hemoglobinuria)
- Coags if hemolytic/DIC suspected
- BNP + CXR for TRALI vs TACO
- Blood cultures if febrile (bacterial contamination)
Management
Management by Type
| Reaction | Immediate | Ongoing |
|---|---|---|
| Acute Hemolytic | STOP, NS bolus | UOP >1 mL/kg/hr, monitor for DIC |
| FNHTR | Acetaminophen | Can restart slowly. Pre-medicate future |
| Allergic | Diphenhydramine 25–50mg IV | Restart after urticaria resolves. Washed products for recurrence |
| Anaphylactic | Epinephrine 0.3–0.5mg IM | IgA level, future: washed/IgA-deficient products |
| TRALI | O2, intubation PRN | Lung-protective vent, resolves 48–72h. NO diuretics |
| TACO | Furosemide 20–40mg IV | O2, slow future transfusions (1 mL/kg/hr) |
🔄 Updated Practice: Old teaching: premedicate ALL transfusions with acetaminophen + diphenhydramine. Current practice: only premedicate if prior febrile or allergic reaction history. Routine premedication does not prevent serious reactions (TRALI, hemolytic) and delays recognition of early symptoms. Leukoreduction is more effective than premedication at preventing FNHTR.
Medications
Key Medications
| Drug | Indication | Dose |
|---|---|---|
| Acetaminophen | FNHTR, pre-med | 650mg PO/PR |
| Diphenhydramine | Allergic reactions | 25–50mg IV/PO |
| Epinephrine | Anaphylaxis | 0.3–0.5mg IM (1:1000) |
| Furosemide | TACO | 20–40mg IV |
Prevention Strategies
| Strategy | Prevents | Details |
|---|---|---|
| Bedside verification (two-person check) | Acute hemolytic (ABO mismatch) | Verify patient ID, blood type, unit label at bedside. Clerical error is #1 cause of fatal reactions |
| Leukoreduced products | FNHTR, CMV, HLA alloimmunization | Universal in most blood banks. More effective than premedication King et al, Transfusion 2004 |
| Slow infusion rate | TACO | 1 mL/kg/hr (vs standard 2-4 mL/kg/hr) for at-risk patients. Maximum 4h per unit |
| Washed products | Anaphylaxis (IgA deficiency) | Removes >99% of plasma proteins including IgA |
| Furosemide 20 mg IV between units | TACO | For patients with CHF, renal failure, or fluid-sensitive states. Give between units, not prophylactically before first unit |
| Irradiated products | TA-GVHD | 25 Gy gamma irradiation. Required for immunocompromised patients |
On Rounds
How do you differentiate TRALI from TACO?
TRALI = non-cardiogenic (low BNP, bilateral infiltrates, normal CVP, hypotension, no diuretic response). TACO = cardiogenic (high BNP, JVD, HTN, responds to diuretics). TRALI is the leading cause of transfusion death.
What is the #1 cause of fatal acute hemolytic reactions?
Clerical error, wrong blood to wrong patient (ABO mismatch). Bedside verification is mandatory.
Which patients are at risk for anaphylactic transfusion reactions?
IgA-deficient patients with anti-IgA antibodies. Need washed blood products or IgA-deficient donors.
What labs differentiate TRALI from TACO?
BNP is the key differentiator. TRALI: BNP low/normal (<200 pg/mL), bilateral infiltrates on CXR, hypotension, normal CVP, no response to diuretics. TACO: BNP elevated (>1000 pg/mL), JVD, hypertension, responds to diuretics. Fluid balance also helps - TACO typically has positive fluid balance. Li et al, Transfusion 2014
What is the most common cause of transfusion-related mortality?
TRALI was historically the #1 cause of transfusion-related death. Since 2014-2016 mitigation strategies (predominantly male plasma, avoiding high-titer female donors), TRALI incidence has decreased significantly. Toy et al, Transfusion 2012 TACO is now the most commonly reported cause of transfusion fatalities to the FDA. Acute hemolytic reactions from ABO mismatch remain the most preventable cause of death.
Why are platelets at higher risk for bacterial contamination than RBCs?
Platelets are stored at room temperature (20-24C) on continuous agitation, which promotes bacterial growth. RBCs are stored at 4C, which inhibits most bacterial growth. Bacterial contamination rate: platelets ~1:1000-3000 units vs RBCs ~1:500,000. Most common organisms in platelets: skin flora (Staphylococcus, Streptococcus). In RBCs: cold-growing organisms (Yersinia enterocolitica). This is why platelet units are screened with bacterial detection methods.
When should you restart a transfusion after a reaction?
Only mild allergic reactions (isolated urticaria, no hemodynamic changes) can be restarted after treatment with diphenhydramine and symptom resolution. The rate should be slowed. NEVER restart for: fever/rigors (could be early hemolytic or septic), hypotension, respiratory symptoms, suspected TRALI/TACO, or any hemolytic reaction. When in doubt, do not restart. Send the unit back to blood bank for investigation.
What is the pathophysiology of TRALI?
Two-hit model: (1) First hit: patient's neutrophils are primed by an underlying condition (sepsis, surgery, massive transfusion). (2) Second hit: donor antibodies (anti-HLA or anti-HNA) or bioactive lipids in stored blood activate the primed neutrophils. Activated neutrophils release toxic mediators in the pulmonary vasculature, causing endothelial damage and non-cardiogenic pulmonary edema. This is why using male-only plasma (which lacks anti-HLA from pregnancy) reduces TRALI incidence.
Which transfusion reaction is associated with IgA deficiency?
Anaphylactic transfusion reaction. Patients with selective IgA deficiency (~1:700 prevalence) can develop anti-IgA antibodies. When transfused with IgA-containing plasma, they develop severe anaphylaxis (hypotension, bronchospasm, angioedema) within minutes. Prevention: use washed blood products (removes >99% of plasma IgA) or obtain products from IgA-deficient donors. Check IgA level in patients with unexplained anaphylaxis during transfusion.
Monitoring
| Parameter | Frequency | Target |
|---|---|---|
| Vital signs | q15min during transfusion | Fever, hypotension, desaturation |
| SpO2 | Continuous | Drop = TRALI/TACO/anaphylaxis |
| UOP | Hourly if hemolytic | >1 mL/kg/hr |
| Hemolysis labs | Post-reaction | Hgb, LDH, haptoglobin, DAT |
Clinical Examples
📋 Case 1 - TRALI After Plasma Transfusion
Patient: 45M post-op day 2 from exploratory laparotomy for perforated appendix. Receiving FFP for mildly elevated INR (1.8) before drain removal.
Event: 3 hours into second unit of FFP, develops acute dyspnea, SpO2 82% on RA, BP 78/45. Bilateral crackles. No JVD, no peripheral edema.
Labs: BNP 85 (normal), CXR shows bilateral infiltrates. CBC, troponin unremarkable.
Assessment: TRALI - acute hypoxemia + bilateral infiltrates + low BNP + no volume overload + within 6h of transfusion. High-risk: recent surgery (neutrophil priming).
Management: STOP transfusion. Supplemental O2, intubated for P/F <150. Lung-protective ventilation (6 mL/kg). NO diuretics (not cardiogenic). Hypotension treated with IVF. Notified blood bank. Improved over 48h, extubated day 3. Donor testing revealed anti-HLA antibodies.
📋 Case 2 - TACO in Elderly CHF Patient
Patient: 82F with CHF (EF 30%) and CKD3, admitted for symptomatic anemia (Hgb 5.8). Ordered for 2 units pRBCs.
Event: Near end of second unit (transfused at standard rate), develops progressive dyspnea, orthopnea. BP 185/95, HR 100, SpO2 88%. JVD present, bilateral crackles and lower extremity edema.
Labs: BNP 2,850 (baseline 800). CXR: vascular congestion with bilateral pleural effusions.
Assessment: TACO - volume overload in CHF patient. Elevated BNP, hypertension, JVD, responds to diuretics.
Management: STOP transfusion. Furosemide 40 mg IV with good diuresis (1.5 L in 4h). O2 via NRB, BiPAP briefly. Symptoms resolved. Future orders: 1 unit at a time, rate 1 mL/kg/hr, furosemide 20 mg IV between units.
📋 Case 3 - Acute Hemolytic Reaction from ABO Mismatch
Patient: 55F with GI bleed receiving pRBC transfusion. Nurse notes blood type on label says "B+" but patient wristband says "A+". 50 mL already infused.
Event: Patient develops acute flank pain, fever to 39.5, dark urine, rigors. BP drops to 80/50. Urine output = dark red.
Labs: DAT strongly positive. Plasma pink (free hemoglobin). LDH 1,200, haptoglobin undetectable, total bili 4.8, Cr rising. UA: hemoglobinuria.
Assessment: Acute hemolytic transfusion reaction from ABO mismatch (clerical error). Anti-A antibodies lysing B-positive donor cells.
Management: STOP immediately. Aggressive NS resuscitation targeting UOP >1 mL/kg/hr (to prevent renal failure from hemoglobin casts). Serial CBC, coags (watch for DIC), renal function. Blood bank investigation. Incident report. Patient stabilized, Cr peaked at 2.8, returned to baseline by day 5.
Summary
Summary
First Move Is Always the Same
Stop the transfusion for any suspected reaction, then ask questions. Keep the IV open with normal saline, send the bag and a fresh patient sample back to the blood bank, and recheck the identity of patient and unit. Clerical error, the wrong blood to the wrong patient, is the number one cause of fatal acute hemolytic reactions, so the bedside check is where the diagnosis is often made.
Sort by Timing and Vitals
Minutes with fever, flank pain, dark urine and hypotension → acute hemolytic. Minutes with hypotension, bronchospasm and angioedema → anaphylaxis, think IgA deficiency. 1 to 6 h with fever and no hemolysis → febrile non-hemolytic, the most common reaction. Urticaria alone with stable vitals → mild allergic.
TRALI vs TACO
Both give dyspnea and bilateral infiltrates within about 6 hours. TRALI: hypotensive, normal JVP, normal or low BNP, no response to diuretics, treated supportively with lung-protective ventilation and resolving in 48 to 72 h. TACO: hypertensive, raised JVP, elevated BNP, responds to diuresis. Giving furosemide to TRALI does nothing and drops an already low blood pressure further.
The Reaction That Kills Most Often
TRALI is the leading cause of transfusion-related mortality. It is not volume overload and cannot be diuresed out; the management is supportive ventilation, and the prevention is at the donor level (male-predominant plasma).
Which Reactions Let You Restart
Mild allergic urticaria may be restarted slowly after an antihistamine. Everything else stays stopped: hemolytic, anaphylactic, TRALI and TACO reactions all mean that unit is finished.
Do Not Forget the Delayed Ones
Delayed hemolytic at 3 to 14 days from an anamnestic response to minor antigens (Kidd, Duffy, Kell) → supportive, antigen-negative units in future. Transfusion-associated GVHD at 4 to 30 days carries over 90% mortality → prevented with irradiated products in at-risk patients. Post-transfusion purpura at 5 to 12 days → IVIG 1 g/kg for 2 days; platelets usually do not work.
Match the Product Modification to the Risk
Irradiated prevents GVHD in the immunocompromised. Leukoreduced reduces febrile reactions and CMV transmission. Washed removes plasma proteins for IgA deficiency and recurrent severe allergic reactions. Ordering the wrong modifier is not a paperwork issue: the wrong product in an at-risk patient is what causes transfusion-associated GVHD.
Prevention and the Premedication Myth
The best prevention is not transfusing. Use a restrictive threshold of Hgb below 7 g/dL in hemodynamically stable adults; liberal transfusion does not improve outcomes and adds risk. Do not routinely premedicate: acetaminophen and diphenhydramine before every unit does not prevent serious reactions, and should be reserved for patients with a prior febrile or allergic reaction.
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