Blood Transfusions Flashcards
What surface antigen is A, B & O? [3]
A = N-acetyl-galactosamine B = Just Galactose O = No antigen (it's gene is a non-functional allele)
How are blood groups inherited? [2]
O is recessive
A & B are dominant
How do you decide which blood group to give when giving red cells?
The donor musn’t have any antigens (A or B) that the recipient doesn’t have or the host will attack the donor cells
So who can give/receive group A red cells?
A can give to A or AB (as they won’t react to the donor A antigen)
The can only receive from A or O
Who can give/receive group B red cells?
B can give to B or AB
Can only receive from B or O
Who can give/receive group O red cells?
Can donate to anyone (as no antigens)
But can’t receive from anyone but O
Who can give/receive group AB red cells?
Only donates to AB and can take from anyone
The rules for donating fresh frozen plasma are different to red cells. How do blood groups affect FFP donation? [2]
With FFP donor must have all the antigens the recipient has (can also have extra.) But it won’t work if the recipient has antigens not present in the donor
So who can give/receive group A FFP?
Can give to A or O
Receive from A + AB
So who can give/receive group B FFP?
Can give to B or O
Can only receive from B or AB
So who can give/receive group AB FFP?
Give to A, B, AB or O (so anyone)
Can receive from AB
So who can give/receive group O FFP?
O can only donate to O but they can receive from anyone
Other than the ABO blood groups the other main grouping is RhD +ve vs RhD -ve. What’s the danger of RhD? [2]
If RhD -ve people receive RhD +ve blood they will create Anti-D antibodies –> Transfusion reaction
How is RhD involved in maternity? [2]
An RhD -ve mother can pass on anti-D antibodies to their newborn.
If they’re RhD +ve the newborn will develop haemolytic disease
What do we test a blood donor for before using their blood? [3]
Behavioural screen (sex, age, travel, tattoos etc) ABO & RhD group testing Inf screening (HEP B,C,E, HIV & syphilis)
Which group is the universal plasma donor?
AB
Blood products: how are they obtained?
Packed red cells
Platelets
FFP
Cryoprecipitate
Packed red cells - obtained by centrifugation of whole blood
Platelets - pooled donation or aphaeresis
FFP - whole blood or aphaeresis
Cryoprecipitate - pooled donation
Which blood product has highest risk of bacterial contamination?
Platelets: Highest risk of bacterial infection AS STORED AT ROOM TEMP
Symptoms of Transfusion Reaction
Symptoms of mild transfusion reaction
Urticaria
Flushing
Temperature rise of <2oC
Symptoms of Transfusion Reaction
Moderate symptoms
Wheezing
Angioedema
Hypotension
Temperature rise of >2oC
Symptoms of Transfusion Reaction
Severe Symptoms:
Hypotension with evidence of shock
Respiratory compromise such as stridor or anaphylaxis
Temperature rise of >2oC
Management of Transfusion Reaction
Mild
Paracetamol
Antihistamines
Management of Transfusion Reaction
Moderate
Stop transfusion immediately
Assess whether pyrexia is in keeping with the patient’s clinical history
If not, send unit of blood for culture and take blood cultures from the patient
Management of Transfusion Reaction
Severe
Acute management of airway, breathing, and circulation
Specific measures such as adrenaline IM 1:1000 are needed if there is evidence of anaphylaxis
Same as for moderate symptoms
Acute haemolytic transfusion reactions, e.g. ABO blood group incompatibility
Immunology pathogenesis, timing of reaction
Happens immediately. IgM mediated; intravascular haemolysis secondary to activation of complement.
Delayed haemolytic transfusion reactions
Immunology pathogenesis, timing of reaction
Between 1-14 days after transfusion. IgG mediated; extravascular haemolysis;
due to the development of clinically significant alloantibodies which may not have been detected during pre- transfusion testing.
Non haemolytic allergic reactions vs febrile non-haemolytic reactions
Difference in pathogenesis and prevention methods
Non haemolytic allergic reactions - pruritus, urticaria. occur due to reactions to plasma protein and are prevented by leucodepletion.
Febrile non-haemolytic reactions occur o antibodies against human leucocyte antigens (HLA). Can be prevented by pre-medication with paracetamol.
TACO - Transfusion associated circulatory overload
Signs, risk factors, management
- Excessive rate of transfusion, pre-existing heart failure
- Pulmonary oedema, hypertension
- Use of diuretics; slowing the rate of transfusion; reassessing clinical need for each subsequent unit of transfusion.
