Haematology - Blood Transfusions

Question 1

What are the thresholds for a red cell transfusion?

Answer 1

• Transfusion dependent pts threshold = 70-90g/L
• Asymptomatic threshold = 70g/L
• Symptomatic threshold = 80g/L
• CHD pts threshold = 90-100g/L

Question 2

How should a red cell transfusion take place?

Answer 2

• 1 unit at a time (unless active bleeding)
• Can be transfused “stat”, otherwise over 2-3hrs
• Treat iron/folate/B12 deficiency first, unless active bleeding

Question 3

What are some indications for a platelet transfusion?

Answer 3

Consumptive disorders
- TTP
- DIC
- HIT
- Don’t transfuse unless active bleeding (plts will be destroyed)

Question 4

What is the threshold for platelet transfusions?

Answer 4

• <10bn/L
• Sepsis = <20bn/L

Question 5

What are the indications for a FFP transfusion?

Answer 5

• Patient is bleeding
• Patient is undergoing a procedure (e.g. surgery)

Question 6

What does the dose of FFP depend on?

Answer 6

• Weight
• INR
• Target INR

Question 7

What needs to be done first before transfusing FFP?

Answer 7

• Consider using Vitamin K (if appropriate)
• Allow to thaw for 30 mins

Question 8

What are some immediate, immune reactions to a blood transfusion?

Answer 8

• Wrong blood - ABO
• Febrile non-haemolytic
• Allergy/anaphylaxis
• Transfusion related acute lung injury (TRALI)

Question 9

What are some immediate, non-immune reactions to a blood transfusion?

Answer 9

• Bacterial infection
• Transfusion associated cardiac overload (TACO)

Question 10

What are some delayed immune reactions to a blood transfusion?

Answer 10

• Delayed haemolytic transfusion reaction (DHTR)
• Post-transfusion purpura
• Transplant -associated GVHD

Question 11

What are some delayed non-immune reactions to a blood transfusion?

Answer 11

• Viral infections
• Iron overload

Question 12

What adverse transfusion reactions occur <24hrs, and their features?

Answer 12

Anaphylaxis:
- Sx within minutes
- Risk increases with IgA deficiency

ABO-incompatibility:
- Sx occur mins-hrs
- Intravascular haemolysis - IgM mediated

Bacterial contamination:
- Sx occur mins-hrs
- More common with platelet transfusions

Febrile non-haemolytic transfusion reaction:
- Rise in temperative <=1C without circulatory collapse
- Caused by release of cytokines by leukocytes + prevented by leukodepletion

Transfusion-related circulatory overload (TACO)
- Sx of pulmonary oedema/fluid overload within hrs
- Signs of HF (Raised JVP, Raised PCWP)
- Hypertensive
- Tx: furosemide

Transfusion-related acute lung injury (TRALI)
- Sx similar to TACO, but absent HF
- Occurs <6hrs
- Hypotensive
- Causes by interaction with anti-HLA Abs in donor blood with recipient

Question 13

What adverse transfusion reactions occur >24hrs, and what are their features?

Answer 13

Delayed-haemolytic Transfusion Reaction:
- Occurs <1wk
- Extravascular haemolysis (IgG-mediated)
- Jaundice + splenomegaly

GVHD:
- Sx: Diarrhoea, liver failure, SKIN DESQUAMATION, BM failure
- Donor lymphocytes recognise recipient’s HLA as foreign + attack gut, liver, skin + bone marrow
- Prevent by irradiating blood components for immunosuppressed recipients