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Haematology > Blood Transfusion > Flashcards

Blood Transfusion Flashcards

1
Q

What are the requirements for being a blood donor

A

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

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2
Q

What is donated blood tested for

A

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

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3
Q

How are blood donations stored

A

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

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4
Q

Why do stored platelets require agitation

A

If not they all clump together and cant be used

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5
Q

What blood products are available for transfusion

A

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

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6
Q

Which blood groups are dominant

A

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

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7
Q

What are the most common blood types

A

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

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8
Q

What is Landsteiner’s law

A

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

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9
Q

Which blood group can be given to anyone

A

O-

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10
Q

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

A

Transfusion reactions and haemolytic disease of the fetus and newborn

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11
Q

How can people be exposed to foreign blood antigens

A

Pregnancy

Transfusion

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12
Q

What pre-transfusion tests are carried out

A

Identify ABO and RhD group of patient

Identify presence of clinically significant red cell antibodies

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13
Q

How do you identify plasma antibodies

A

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

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14
Q

How do you identify antigens present on RBC

A 
Use reagents with known antibody specificity 
Anti A (blue), Anti-B (yellow) and anti-D (clear)
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15
Q

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

A

Positive

The cells are reacting to the antibodies

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16
Q

What is a crossmatch

A

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

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17
Q

What are the indication for a red cell transfusion

A

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

Major bleeding

18
Q

What are the indications for platelet transfusion

A

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

19
Q

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

A

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

20
Q

When is CMV negative blood required

A

Neonates and pregnancy

21
Q

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

A

They could be in the process of creating antibodies

22
Q

How are patients monitored during blood transfusions

A

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

23
Q

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

A

85% are D positive

24
Q

What is the most common cause of transfusion related death

A

TACO

Transfusion associated circulatory overload

25
Q

What is TACO

A

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

26
Q

How do you manage TACO

A

Oxygen and diuretics

Transfuse the minimum volume and do it slowly to avoid TACO

27
Q

Is cross matching always carried out

A

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

28
Q

What is the purpose of cross matching

A

It is done to prevent transfusion reactions

29
Q

What are some of the complications of blood transfusion

A

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

30
Q

Which viruses can be transmitted by blood transfusion

A

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

31
Q

How do you manage iron overload in people requiring repeat transfusions

A

Iron chelating drugs such as desferrioxamine

This causes the excess iron to be excreted

32
Q

What are some of the consequences of iron overload

A

Endocrine dysfunction
Cardiac disease
Liver disease

33
Q

Describe delayed haemolytic transfusion reactions

A

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

34
Q

Describe a mild, non-haemolytic transfusion reaction

A

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

35
Q

Which blood product is most likely to have bacterial contamination

A

Platelets

36
Q

How do you manage bacterial contamination of blood component

A

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

37
Q

What are the signs and symptoms of an acute transfusion reaction

A

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

38
Q

How do you manage an acute transfusion reaction

A

Often happens early in transfusion

Stop transfusion and assess patient with ABCDE

39
Q

What causes an acute haemolytic transfusion reaction

A

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

40
Q

How do you manage an acute haemolytic transfusion reaction

A

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

41
Q

Describe a direct coombes test

A

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

Haematology (8 decks)

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