Blood Transfusion 1

Question 1

What are antigens in the context of rbc?

Answer 1

Protein molecules found on the surface of red cells

Question 2

What happens if you give ABO incompatible blood?

Answer 2

Intravascular haemolysis which is potentially fatal

Question 3

What proportion of the population are RhD positive and what does this mean?

Answer 3

85%

Can receive RhD positive or negative blood

Question 4

What proportion of the population are RhD negative and what does this mean?

Answer 4

15%
They lack RhD antigen
Can make immune anti-D if exposed to RhD positive red cells

Question 5

What are some properties of immune anti-D antibodies?

Answer 5

Are IgG (so cross the placenta)
Do not cause direct agglutination of rbc
Cause delayed haemolytic transfusion reaction

Question 6

What can happen as a result of RhD negative pregnant women exposed to RhD positive blood?

Answer 6

Produce immune anti D which can cause haemolytic disease of the newborn or severe foetal anaemia and heart failure (hydrops fetalis) in pregnancy

Question 7

In blood group testing, what is seen in a positive result in reverse testing?

Answer 7

Agglutination (clumping)

Question 8

How are antibody screens conducted?

Answer 8

On patient plasma

Indirect antiglobulin technique (IAT) bridges red cells coated by IgG to form a visible clump

Question 9

How is a full serological crossmatch conducted?

Answer 9

Indirect antiglobulin technique
Patient plasma incubated with donor red cells, will pick up antibody antigen reaction that could destroy the red cells and cause extravascular haemolysis
Agglutination = incompatible

Question 10

What is an immediate spin?

Answer 10

Incubate patient plasma and donor red cells and spin, will detect ABO incompatibility

Question 11

What are the pillars of patient blood management?

Answer 11

Optimise haemopoiesis
Minimise blood loss and bleeding
Harness and optimise physiological tolerance of anaemia

Question 12

What are methods, particularly in surgical setting, which minimise blood loss and bleeding?

Answer 12

Stop anticoagulation / anti-platelet agents
Tranexamic acid
Blood sparing techniques
Cell salvage

Question 13

What blood targets should be achieved pre-operatively?

Answer 13

Ferritin 100ug/l
TSATs 25-30%
B12>350ng/l
Serum folate >5ug/L

Question 14

What are the methods pre-operatively to optimise haemopoiesis?

Answer 14

IV / oral iron
B12 replacement
Folate replaceErythropoietin sc

Question 15

What are the storage and giving standards for RBCs?

Answer 15

Stored at 4oC for 35 days
Must be transfused within 4 hours of leaving the fridge
Transfer 1 unit of RBC over 2-3 hrs

Question 16

What are the storage and giving standards of platelets?

Answer 16

Stored at 20oC for 7 days

Transfuse 1 unit of platelets over 20-30 minutes

Question 17

What are the matching requirements for RBCs?

Answer 17

Give ABO/D compatible
Group O negative in emergency
Consider special requirements

Question 18

What are the matching requirements for platelets?

Answer 18

ABO/D antigens weakly expressed
Should be D compatible
Consider special requirements
If group O given to A, B or AB patients select ‘high-titre’ negative (anti-A/B antibodies)

Question 19

What are the matching requirements for FFP and cryoprecipitate?

Answer 19

Give ABO compatible (D group does not matter)
AB plasma can be given to all groups as it has no anti-A/B antibodies but is in short supply
No need to cross match but does take 30-40 mins to thaw

Question 20

What are the storing and giving requirements of FFP?

Answer 20

Once thawed can be kept at 4oC for 24 hrs

Transfuse 1 unit over 20-30mins

Question 21

What are the storage and giving requirements for cryoprecipitate?

Answer 21

Once thawed has to be kept at room temperature and used within 4 hrs
Transfuse 1 unit over 20-30 mins

Question 22

What are examples of RBC transfusion indications?

Answer 22

Major blood loss - if >30% blood volume lost
Per-op, critical care - Hb<70g/L vs 80g/L
Post chemo - Hb <80g/L

Question 23

What is the increment in Hb provided by 1 unit of RBC?

Answer 23

10g/L in a 70-80kg patient

Question 24

What are some examples of platelet transfusion indications?

Answer 24

Massive transfusion - aim plts >75x10^9/l
Prevent bleeding (post chemo) - if <10x10^9/L (<20 if sepsis)
Prevent bleeding (surgery) - <50 x10^9/L (<100 if critical site: eye, CNS, polytrauma)

Question 25

In what cases is a platelet transfusion contraindicated?

Answer 25

Heparin-induced thrombocytopenia thrombosis (HiTT)

Thrombotic thrombocytopenic purpura (TTP)

Question 26

What is the rise in platelets following one adult treatment dose?

Answer 26

30-40x10^9/L

Question 27

When is the best time to give platelets for a procedure?

Answer 27

Whilst the procedure is being carried out

Question 28

What are the indications for FFP?

Answer 28

Massive transfusion - early, aim PT and APTT ratio at <1.5

Liver disease (no benefit in patients with PT ratio <1.5)

Replacement of single coagulation factor deficiency

DIC in presence of bleeding and abnormal coagulation results

Thrombotic Thrombocytopenic purpura (TTP)

Question 29

What is the dose for FFP?

Answer 29

15-20ml/kg

4 units in 70kg man

Question 30

What are the components of cryoprecipitate?

Answer 30

Fibrinogen
fVIII and vWF
Fibronectin
fXIII
Platelet microparticles
IgA
Albumin

Question 31

What is the adult dose of cryoprecipitate?

Answer 31

2 pools (10 donors)

Question 32

When is CMV negative blood required?

Answer 32

Intra-uterine / neonatal transfusions and for elective transfusions in pregnant women

Question 33

When is irradiated blood required?

Answer 33

Highly immunosuppressed patients who cannot destroy incoming donor lymphocytes which can cause fatal transfusion associated graft vs host disease

Question 34

When are washed cells required?

Answer 34

In patients who have severe allergic reactions to some donors’ plasma proteins