Blood Transfusion

Question 1

What are the requirements for being a blood donor

Answer 1

Hb 135g/L men
Hb 125g/L women
Weight 50kg
Complete a donor questionnaire - rules out illnesses etc that would be inappropriate

Question 2

What is donated blood tested for

Answer 2

HIV, Hep B, Hep C, Hep E, HTLV, Syphilis

Question 3

How are blood donations stored

Answer 3

Red cells- stored at 4°C for 35 days
FFP- stored -30°C for 3 years
Platelets- stored 22°C for 7 days with agitation

Question 4

Why do stored platelets require agitation

Answer 4

If not they all clump together and cant be used

Question 5

What blood products are available for transfusion

Answer 5

Blood components - Red cells, FFP, platelets, cryoprecipitate

Blood products - Anti-D immunoglobulin, prothrombin complex concentrate

Blood products from pharmacy - Iv immunoglobulin, human albumin, specific Ig

Question 6

Which blood groups are dominant

Answer 6

A and B are dominant over O
A and B are co-dominant
O is silent

Question 7

What are the most common blood types

Answer 7

O is most common (47%)
A (42%)
B (8%)
AB (3%)

Question 8

What is Landsteiner’s law

Answer 8

When an individual lacks the A or B antigen the corresponding antibody is produced in their plasma

e.g. If you have the A antigen then you will have antibodies to B in your circulation

Question 9

Which blood group can be given to anyone

Answer 9

O-

Question 10

What can anti-D antibodies cause if presented with D antigens

Answer 10

Transfusion reactions and haemolytic disease of the fetus and newborn

Question 11

How can people be exposed to foreign blood antigens

Answer 11

Pregnancy

Transfusion

Question 12

What pre-transfusion tests are carried out

Answer 12

Identify ABO and RhD group of patient

Identify presence of clinically significant red cell antibodies

Question 13

How do you identify plasma antibodies

Answer 13

Use red cells with known antigen specificity and add the patients plasma to test against them
Then add anti-human globulin to facilitate red cell agglutination

Question 14

How do you identify antigens present on RBC

Answer 14

Use reagents with known antibody specificity 
Anti A (blue), Anti-B (yellow) and anti-D (clear)

Question 15

If cells agglutinate when typing is it a positive or negative result

Answer 15

Positive

The cells are reacting to the antibodies

Question 16

What is a crossmatch

Answer 16

Add the donor cells to a sample of the patient plasms to make sure they don’t react
Agglutination indicates donor cells are incompatible

Question 17

What are the indication for a red cell transfusion

Answer 17

Symptomatic anaemia Hb<70g/L (80g/L if cardiac disease)

Major bleeding

Question 18

What are the indications for platelet transfusion

Answer 18

Prophylaxis in patients with bone marrow failure and very low platelet counts
Treatment of bleeding in thrombocytopenic patient
Prophylaxis prior to surgery/ procedure in thrombocytopenic patient

Question 19

What are the indications for fresh, frozen plasma (FFP) transfusion

Answer 19

Primary use is to replace clotting factors
Treatment of bleeding in patient with coagulopathy
Prophylaxis prior to surgery or procedure in patient with coagulopathy
Management of massive haemorrhage
Transfuse early in trauma

Question 20

When is CMV negative blood required

Answer 20

Neonates and pregnancy

Question 21

Why does recent transfusion or pregnancy reduce the validity of the pre-transfusion sample

Answer 21

They could be in the process of creating antibodies

Question 22

How are patients monitored during blood transfusions

Answer 22

Observations before blood is commenced
Observe every 15 mins during the transfusion
Observations within 60 minutes of completion

Question 23

Is it more common to be RhD positive or negative in the UK

Answer 23

85% are D positive

Question 24

What is the most common cause of transfusion related death

Answer 24

TACO

Transfusion associated circulatory overload

Question 25

What is TACO

Answer 25

Transfusion associated circulatory overload Causes pulmonary oedema, positive fluid balance, respiratory distress, increased BP and JVP and CXR changes More at risk if elderly or if you have HF

Question 26

How do you manage TACO

Answer 26

Oxygen and diuretics | Transfuse the minimum volume and do it slowly to avoid TACO

Question 27

Is cross matching always carried out

Answer 27

It should be The exception is in emergency situations where you cant delay giving blood to do the test. This is why O- is used in emergencies

Question 28

What is the purpose of cross matching

Answer 28

It is done to prevent transfusion reactions

Question 29

What are some of the complications of blood transfusion

Answer 29

Acute transfusion reactions (ATR) Acute haemolytic transfusion reactions (AHTR) Bacterial contamination of blood component Transfusion associated circulatory overload (TACO) Mild reaction Delayed haemolytic transfusion reactions Viral transmission Iron overload

Question 30

Which viruses can be transmitted by blood transfusion

Answer 30

Hep B HIV Hep C All very rare as blood in the UK is now screened

Question 31

How do you manage iron overload in people requiring repeat transfusions

Answer 31

Iron chelating drugs such as desferrioxamine | This causes the excess iron to be excreted

Question 32

What are some of the consequences of iron overload

Answer 32

Endocrine dysfunction Cardiac disease Liver disease

Question 33

Describe delayed haemolytic transfusion reactions

Answer 33

Patient mounts delayed immune response to red cell antigen (usually IgG) Extracellular haemolysis 5-10 days post transfusion Transfused cells destroyed

Question 34

Describe a mild, non-haemolytic transfusion reaction

Answer 34

Mild allergic reaction due to white cell antibodies or hypersensitivity to donor plasma proteins Will have a rise of 1-2 degrees in temp or rash Continue transfusion and monitor Consider giving them paracetamol or anti-histamine

Question 35

Which blood product is most likely to have bacterial contamination

Answer 35

Platelets

Question 36

How do you manage bacterial contamination of blood component

Answer 36

Culture patient and remains of unit Treat supportively with broad spectrum antibiotics Inform transfusion lab so other units can be quarantined

Question 37

What are the signs and symptoms of an acute transfusion reaction

Answer 37

Symptoms; chills, rigors, rash, flushing, feeling of impending doom, collapse, loin pain, resp distress Signs; fever, tachycardia, hypotension

Question 38

How do you manage an acute transfusion reaction

Answer 38

Often happens early in transfusion | Stop transfusion and assess patient with ABCDE

Question 39

What causes an acute haemolytic transfusion reaction

Answer 39

ABO incompatible transfusion Binding of IgM anti-A or anti-B antibodies to their corresponding antigen leads to complement activation and lysis of transfused cells Release of inflammatory cytokines This leads to shock, increased vascular permeability, disseminated intravascular coagulation and renal failure Often fatal and can be quickly

Question 40

How do you manage an acute haemolytic transfusion reaction

Answer 40

Stop transfusion and use supportive measure to stabilise patient Return unit to transfusion lab and inform of clinical situation Repeat transfusion blood samples and take bloods Lab will repeat ABO and RhD group of pre and post transfusion samples, direct antiglobulin test, repeat crossmatch and send remains of unit for culture

Question 41

Describe a direct coombes test

Answer 41

Anti-globulin is added to a cell sample from the patient If the cells clump together it shows there are antibodies on the surface Used for the diagnosis of haemolytic anaemia