Blood Transfusion 2 Flashcards
What are acute (<24 hours) adverse reactions to transfusions?
Acute haemolytic (ABO incompatible)
Allergic/anaphylaxis
Infection (bacterial)
Febrile non-haemolytic
Respiratory:
- Transfusion associated circulatory overload (TACO)
- Acute lung injury (TRALI)
What are delayed (>24 hours) adverse reactions to transfusions?
Delayed haemolytic transfusion reaction (antibodies).
Infection viral, malaria, vCJD.
TA-GvHD.
Post transfusion purpura.
Iron overload.
What are signs and symptoms of an acute adverse reaction to transfusion?
Many acute reactions start as a rise in temp or pulse or fall in BP even before patient feels symptoms.
Symptoms: Depends on cause, but can include fever, rigors, flushing, vomiting, dyspnoea, pain at transfusion site, loin pain/ chest pain, urticaria, itching, headache, collapse etc.
How are acute adverse reactions to transfusion detected?
Monitoring may be the ONLY way to detect reaction if patient unconscious.
Baseline temp, pulse, respiratory rate, BP before transfusion starts.
Repeat after 15 mins (as most, but not all, reactions will start within 15 mins).
Ideally repeat hourly and at end of transfusion (as occasionally reactions start after transfusion finished).
What is a febrile non-haemolytic transfusion reaction (FNHTR)?
Mild/moderate
During/soon after transfusion (blood or platelets), rise in temperature of 10C, chills, rigors.
Common before blood was leucodepleted, now rarer.
Have to stop or slow transfusion; may need to treat with paracetamol.
Cause: White cells can release cytokines during storage.
What are allergic transfusion reactions?
Mild/moderate
Common especially with plasma.
Mild urticarial or itchy rash sometimes with a wheeze.
During or after transfusion.
Usually have to stop or slow transfusion IV antihistamines to treat (and prevent in future if recurrent).
Cause:
- Allergy to a plasma protein in donor so may not recur again, depending on how common the allergen is.
- Commoner in recipients with other allergies and atopy.
What happens if the wrong blood is given?
Severe/fatal.
Symptoms and signs of acute intravascular haemolysis- IgM.
Restless, chest/ loin pain, fever, vomiting, flushing, collapse, haemoglobinuria (later): ↓BP & ↑HR (shock), ↑Temp.
Stop transfusion – check patient / component.
Take samples for FBC, biochemistry, coagulation.
Repeat x-match and Direct Antiglobulin Test (DAT) Discuss with haematology doctor ASAP.
Why are patients sometimes given the wrong blood?
Failure of bedside check giving blood
Wrongly labelled blood sample
Laboratory error
What happens if bacterial contamination of product occurs?
Severe/fatal.
Similar to wrong blood reaction.
Restless, fever, vomiting, flushing, collapse. ↓BP & ↑HR (shock), ↑Temp.
Bacterial growth can cause endotoxin production which causes immediate collapse.
From the donor (low grade GI, dental, skin infection).
Introduced during processing (environmental or skin).
Platelets >red cells > frozen components (storage temp).
How is bacterial contamination avoided?
Donor questioning
Arm cleaning
Diversion of first 20mL into a pouch (used for testing)
Red cells: Store always in controlled fridge 4C; shelf-life 35 days. If out for 30 mins, need to go back in fridge for 6 hours. Complete transfusion of blood within 4h of leaving fridge i.e. transfuse over 4hrs max.
Platelets: Stored at 22C; shelf-life 7 days (as now screened for bacteria before release) transfuse over 20mins.
All components: Look for abnormalities e.g. clumps of discoloured debris; brown plasma etc.
What is anaphylaxis?
“Severe, life-threatening reaction soon after start of transfusion”
↓BP & ↑HR (shock), very breathless with wheeze, often laryngeal &/or facial oedema.
Mechanism: IgE antibodies in patient cause mast cell release of granules & vasoactive substances. Most allergic reactions are not severe, but few are e.g. in IgA deficiency IgA deficiency.
1:300 - 1:700 (common); where in 25%, anti-IgA antibodies develop in response to exposure to IgA (transfusion – especially with plasma); but only minority ever have transfusion reactions- frequency is 1:20,000 - 1:47,000.
What are respiratory complications of transfusions?
Moderate, severe or fatal
Transfusion Associated Circulatory Overload (TACO)
Transfusion Related Acute Lung Injury (TRALI)
Transfusion Associated Dyspnoea (TAD)
What is transfusion related circulatory overload (TACO)?
Pulmonary oedema/fluid overload.
Often lack of attention to fluid balance, especially in cardiac failure, renal impairment, hypo-albuminaemia, those on fluid replacement, very young, very small and very old.
Clinical features: SOB, ↓SAO2 , ↑HR, ↑BP
CXR: Fluid overload/cardiac failure.
What are increased risk factors for TACO?
- Hypoalbuminaemia
- Positive fluid balance prior to transfusion
- Concomitant IV fluids
- Chronic kidney disease
- Diuretic use
- Liver dysfunction
- Cardiac disease
- Peripheral oedema
- Weight <50kg
- Respiratory symptoms of undiagnosed cause
- Pulmonary oedema
What is transfusion related acute lung injury (TRALI)?
Acute lung injury/ARDS.
SOB, ↓O2, ↑HR, ↑BP; (similar to TACO).
CXR: Bilateral pulmonary infiltrates during/within 6 hr of transfusion, not due to circulatory overload or other likely causes.
What is the aetiology of TRALI and how is it managed/prevented?
Mechanism: Anti-wbc antibodies (HLA or neutrophil Abs) in donor. Interact with corresponding ag on patient’s WBCs. Aggregates of WBCs get stuck in pulmonary capillaries → release neutrophil proteolytic enzymes & toxic O2 metabolites → lung damage.
Mechanism not fully understood, antibodies don’t always cause problems.
Prevention: Male donors for plasma & platelets (no pregnancy or transfusion, so no HLA/HNA antibodies).
How do infections present after blood transfusion?
Symptoms months or years after transfusion.
Rely on questioning donors about wellbeing.
Never zero risk – so don’t transfuse unnecessarily!
What are other transfusion transmitted infections?
Malaria
Viral infection: HIV 1+2, HEV, HBV, HCV, HTLV 1+2, Parvovirus, CMV, WNV, Zika.
Variant CJD.
Which viruses can be transmitted via blood transfusion?
CMV: Very immunosuppressed (stem cell transplant) patients can get fatal CMV disease, but leucodepletion removes CMV (in wbc’s) Only give CMV- now for pregnant women (foetus) & neonates.
Parvovirus: Causes temporary red cell aplasia - affects foetuses and patients with haemolytic anaemias e.g. sickle cell; hereditary spherocytosis.
v-CJD: No test. Only 4 cases. but blood services exclude transfused patients as donors, as precaution. Also obtain plasma for those born after 01.01.1996, from outside the UK Since autumn last year decision reversed – now can use UK plasma for all.
COVID-19: Not transmitted by transfusion.
What is a delayed haemolytic transfusion reaction?
1-3% of all patients transfused develop an ‘immune’ antibody to a RBC antigen they lack allomunisation.
If the patient has another transfusion with RBCs expressing the same antigen, antibodies cause RBC destruction extravascular haemolysis (as IgG) so takes 5-10 days.
What are tests for delayed haemolytic transfusion reactions?
- Haemolysis screen
- Bilirubin
- LDH
- Retics
- Hb
- DAT (positive)
- Haemoglobinuria over few days
- Test U&Es – as can cause renal failure
- Repeat G&S for ? new antibody
What is transfusion associated Graft-Versus-Host disease?
Rare, but always fatal (death weeks to months post transfusion).
Donor’s blood contains some lymphocytes (able to divide). Normally, patient’s immune system recognises donor’s lymphocytes as ‘foreign’ and destroys them. In ‘susceptible’ patients (e.g… very IS) - lymphocytes not destroyed.
Lymphocytes recognise patient’s tissue HLA antigens as ‘foreign’ – so attack patient’s gut, liver, skin and bone marrow.
Prevent: Irradiate blood components for very immunosuppressed; or patients having HLA matched components.
Clinical features: Severe diarrhoea, liver failure, skin desquamation, bone marrow failure.
What is post-transfusion purpura?
Purpura appears 7-10 days after transfusion of blood or platelets and usually resolves in 1 to 4 weeks but can cause life threatening bleeding.
Affects HPA -1a negative patients - previously immunised by pregnancy or transfusion (anti-HPA-1a antibody).
Treatment: Infusion of IVIG
What is immune modulation?
Possible increased rate of infections post-op and increased recurrence of cancers in patients who have blood transfusion.
There are conflicting studies so it’s uncertain if this is true
