Blood transfusion

Question 1

where does donated blood come from?

Answer 1

Human source only

Question 2

Why is donated blood a scarce resource?

Answer 2

1 donor can only give 1 pint/unit maximum every 4 months
9000 units of blood are needed every day in the UK
Only has a shelf life of 5 weeks

Question 3

When are blood transfusions used?

Answer 3

Massive bleeding
Anaemic
Only when no alternative is available

Question 4

In terms of blood group what does everyone have on red cell membrane?

Answer 4

Common H stem

Question 5

What do you have if you’re in blood group O?

Answer 5

Only the common H stem, no A or B antigens

Question 6

What do you have if you’re in blood group A or B?

Answer 6

Common H stem and A or B antigen

Question 7

How are the A and B antigens formed?

Answer 7

Adding one or the other sugar residues onto a common glycoprotein and fructose stem on the red cell membranes

Question 8

What determines the antigens?

Answer 8

Corresponding genes

Question 9

What does the enzyme that A gene codes for do?

Answer 9

Adds N-acetyl galactosamine onto common glycoprotein and fructose stem

Question 10

What does the enzyme that B gene codes for do?

Answer 10

Adds galactose

Question 11

In terms of dominance, what are A and B?

Answer 11

Codominant

Question 12

In terms of dominance what is O?

Answer 12

Recessive- doesn’t code for anything

Question 13

In terms of antibodies what will each person have?

Answer 13

Each person will have antibodies against anything that isn’t on the own red cells (they are IgM class)

Question 14

When are these antibodies formed?

Answer 14

From birth naturally

Question 15

What does it mean that these antibodies are complete?

Answer 15

They fully activate the complement cascade to cause haemolysis of red cells

Question 16

What would happen if someone was given blood of an incompatible blood group?

Answer 16

It would be fatal- cytokine storm, lysis, cardiovascular collapse and death

Question 17

How do they test your blood group in a laboratory?

Answer 17

IgM antibodies interact with corresponding antigens to cause agglutination so if group B blood was mixed with group A cells, agglutination would occur so you know he’s not group A

Question 18

What is the frequency of blood group A in the UK?

Answer 18

42%

Question 19

What is the frequency of blood group B in the UK?

Answer 19

8%

Question 20

What is the frequency of blood group O in the UK?

Answer 20

47%

Question 21

What is the frequency of blood group AB in the UK?

Answer 21

3%

Question 22

What does RhD positive mean?

Answer 22

You have the D antigen on the cell membrane

Question 23

What are the genes for RhD groups?

Answer 23

D- codes for D antigen and is dominant

d- codes for no antigen and is recessive

Question 24

What genotype do you have if you are RhD negative?

Answer 24

dd

Question 25

What percentage of people are RhD positive?

Answer 25

85%

Question 26

What blood group is safe for everyone?

Answer 26

O negative

Question 27

What blood group can only given to people of that blood group?

Answer 27

AB positive

Question 28

When does someone that is RhD negative make anti-D antibodies?

Answer 28

After exposure to RhD antigen

Question 29

What are the implications of anti-D antibody formation?

Answer 29

Future blood transfusions have to be RhD negative otherwise would cause delayed haemolytic transfusion reaction Haemolytic disease of newborn- foetus is RhD positive, anti-D antibodies cross placenta and cause haemolysis in foetus and can cause hydrops fetalis and death

Question 30

What is hydrops fetalis?

Answer 30

Accumulation of fluid in foetal tissues or body cavities, most severe form- excessive fluid in peritoneal cavity, pleural cavity and pericardial cavities and soft tissue (oedema)

Question 31

What is in the bag when blood is taken?

Answer 31

Anticoagulant

Question 32

Why is whole blood no longer routinely given to patients?

Answer 32

Parts are used because: More efficient- less is wasted Some components degenerate quickly if stored as whole blood Putting blood in fridge isn't good for coagulation factors and platelets

Question 33

How do you separate blood into parts?

Answer 33

Centrifugation

Question 34

What is fresh frozen plasma?

Answer 34

When you freeze the plasma within 6 hours of donation, preserving all coagulation factors

Question 35

If you take fresh frozen plasma and thaw it overnight in a 4 celsius fridge?

Answer 35

It will separate out into cryoprecipitate at the bottom and some supernatant on top

Question 36

What is cryoprecipitate a very concentrated form of?

Answer 36

``` Fibrinogen (factor 1) Factor 8 Von Willebrand Factor Factor 13 Fibronectin ```

Question 37

What else you can do with plasma?

Answer 37

Put it in a fractionating column and pull of things like albumin and haemophilia factors and anti-D antibodies This isn't done in the UK

Question 38

What temperature is fresh frozen plasma and cryoprecipitate stored at?

Answer 38

-30 celsius

Question 39

What is the shelf life of FFP and cryoprecipitate?

Answer 39

2 years

Question 40

When is FFP used?

Answer 40

Bleeding and abnormal coagulation test results | Reversal of warfarin (which inhibits factor 2, 7, 9 and 10)

Question 41

When is cryoprecipitate used?

Answer 41

Massive bleeding and fibrinogen is low

Question 42

What temperature are platelets stored at and what is their shelf life?

Answer 42

Room temperature and 5 days but have to be constantly agitated

Question 43

Do you need to give platelet that match the blood group?

Answer 43

Yes- Wrong group would be destroyed quickly and could cause RhD sensitisation

Question 44

When are platelets used?

Answer 44

Most haematology patients with bone marrow failure Massive bleeding DIC Low platelets and patient needs surgery

Question 45

How do you keep blood safe for patients?

Answer 45

Test for infections and questioning for risk behaviour

Question 46

How do you prevent harm to donors?

Answer 46

Questioning them to exclude risky ones- e.g. heat problems

Question 47

What infections must all blood be tested for?

Answer 47

``` Hep B Hep C HIV HTLV Syphilis CMV ```

Question 48

What is the problem with testing for infections and what do you have to do as a result of this?

Answer 48

Window period of infections where tests will not show positive You have to exclude high risk donors and use voluntary unpaid donors