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Flashcards in BLOOD TRANSFUSIONS Deck (86):
1

What are the blood components used in transfusion?

Red cells
Platelets
Fresh frozen plasma
Cryoprecipitate
Human albumin solution
Intravenous immunoglobulin
Prothrombin complex concentrate

2

What volume of red cells per kg are needed to increase the Hb by 1g?

3ml/kg

3

What is the volume of a unit of red cells?

280 ml

4

What increase in Hb would you expect to see having given an adult a unit of red cells?

More than 1g/dL

5

At what temperature are donated red blood cells kept at?

6

How long can donated red blood cells be stored for?

35 days

7

What is the group of blood cells that can be transfused to anyone in an emergency?

O Rh-

8

If there was no O negative available but you had not had time to fully crossmatch the patient, what would you give them?

Group specific blood

9

What are the indications for red cell transfusion?

Active bleeding where fluids are unlikely to be sufficient

Bone marrow failure

Abnormal red cells need suppressing or exchanging (eg Hb SS or thalassaemia)

Rarely given for deficiency anaemias such as iron or folate.

10

How many donors are required to make one unit of platelets?

4

11

What is platelet apheresis?

When only the platelets are taken from a donor. The machine they are hooked up to returns the other blood components.

12

How would you check at the bedside that you were giving a good product of platelets?

Shake the bag to check for flocules.

13

What temperature are platelets kept at?

22˚

14

How long can donated platelets be stored for?

7 days

15

Why can platelets be a more common source of infection than other blood products?

Because they are kept at room temperature

16

Do you need to crossmatch platelets for transfusion?

No, only need to know blood group

17

What are the indications for transfusing platelets?

Preventing bleeding in those with thrombocytopenia (eg about to undergo surgery, or leukaemia)

Stopping bleeding in those with thrombocytopenia

18

What is the standard dose of platelets for transfusion?

Either 10ml/kg or 1 pool (4 donations) - whichever is smaller. Very rarely need more.

19

How much donated fresh frozen plasma is contained within 1 unit?

About 300 ml (from 1 donor)

20

What temperature is donated fresh frozen plasma stored at?

-30˚

21

How long can donated fresh frozen plasma be stored for?

1 year

22

How long before transfusion must fresh frozen plasma be thawed?

30 mins

23

How long after thawing must fresh frozen plasma be transfused?

Within the hour otherwise clotting factors begin to degenerate.

24

What is the usual dose of transfused fresh frozen plasma?

12-15 ml/kg which usually equates to about 3 bags

25

Do you need to crossmatch fresh frozen plasma?

No, you just need to know blood group.

26

What is the point of given fresh frozen plasma?

To transfuse clotting factors. Not to replace fluid!

27

What are the indications for transfusing fresh frozen plasma?

If the patient is bleeding AND they have abnormal clotting factor results (PT, APTT)

Reversal of warfarin anticoagulation in urgent surgery if prothrombin complex concentrate is not available.

Liver failure

28

Why is fresh frozen plasma becoming less used?

Because of prothrombin complex concentrate which is now what is used in a warfarin overdose.

29

What two components of cryoprecipitate make it a very useful product?

Fibrinogen
Factor VIII

30

What are the two most common clinical scenarios that require fibrinogen and hence the transfusion of cryoprecipitate?

Postpartum haemorrhage (PPH) - factors from the placenta destroy the fibrinogen
Trauma

31

How many donors are needed to make one dose of cryoprecipitate?

10

32

How many donors are needed to make one bag of cryoprecipitate?

5

33

How many different blood groups have been described?

Over 400

34

What are the two most important blood group categories?

ABO
Rh

35

Other than ABO and Rh, can you name any other clinically important blood groups?

Duffy
Kell
Kidd
S

36

Which of the Rh antigens is being described when we talk about a positive or negative blood group?

Rh D

37

What does ABO represent in terms of blood group?

The red cell antigen. A and B code for genes that alter the H substance. O codes for silent allele that does nothing.

38

What is the inheritance pattern of A and B in terms of blood groups?

They are co-dominant and dominant to O

39

From what age do the ABO antibodies start to become expressed?

3-6 months

40

What type of immunoglobulin are anti-A and anti-B blood cell surface antigen antibodies?

IgM

41

What antibodies will someone with blood group A express?

Anti-B

42

What antibodies will someone with blood group B express?

Anti-A

43

What antibodies will someone with blood group O express?

Anti-A
Anti-B

44

What antibodies will someone with blood group AB express?

None

45

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

42%

46

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

8%

47

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

47%

48

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

3%

49

Which ethnic group contain the highest prevalence of people with blood group B?

Asian

50

In determining the blood group, what is forward and reverse typing?

Forward typing - testing the cells for antigens
Reverse typing - testing the plasma for antibodies

51

Is the RhD antigen dominant or recessive?

Dominant - clue is in the size of the letter

52

What proportion of people are RhD positive?

85%

53

What are the two important implications of giving a RhD negative female RhD positive blood?

There are no immediate implications
The problems come with future blood transfusions and pregnancy

54

Will haemolytic disease of the new born affect the first born child?

Not usually. It is the second child that is affected unless the mother has had a blood transfusion of the wrong group, in which case the first born can be affected.

55

In haemolytic disease of the new born, is the mother RhD positive or negative?

Negative, and therefore once exposed to the RhD antigen will form antibodies against it.

56

Which immunoglobulin type can cross the placenta and cause haemolytic disease of the new born?

IgG antibodies against RhD

57

What are the severe complications of haemolytic disease of the new born?

IgG antibodies against RhD antigen cross the placenta and cause haemolysis of the fetal red cells. This can lead to hydrops fetalis and death.

58

How is haemolytic disease of the new born prevented?

RhD negative women are identified early in pregnancy in routine blood tests. They are then given Rh immunoglobulin (RhIg or RhoGAM) at around the 28th week which prevents them from making antibodies. After the baby is born the mother should receive another dose of RhIg within 72 hours IF the baby is found the RhD positive.

59

What is the purpose of the direct antiglobulin test (DAT), also known as the direct Coomb's test and how is it done?

To detect the cause of haemolytic anaemia, to investigate a transfusion reaction, and to diagnose haemolytic disease of the new born.

The direct test looks for antibodies already stuck to the patients cell in vivo by adding antibodies against other antibodies.

60

What is the purpose of the indirect antiglobulin test, also known as the indirect Coomb's test and how is it done?

To detect antibodies directed against red blood cell
antigens in the patients plasma, in preparation for a blood transfusion, or during pregnancy and at delivery.

The indirect test looks for antibodies in the plasma of the patient and cross reacts them with the cells of the donor or baby. The same antibodies (as the direct test) to the patient's antibodies are then added.

61

What is the purpose of an antibody screen prior to a blood transfusion?

To see if the recipient has any atypical antibodies such as anti-M. It is done by testing plasma from the recipient against panels of red blood cells with known antigens.

62

Do we naturally develop antibodies against all the red cell antigens that we are lacking?

No, in all cases except for the ABO group the development of antibodies only comes post transfusion or pregnancy.

63

What is a crossmatch in terms of blood transfusions?

Plasma from the recipient will be mixed with
a small bit of blood from the donor bag. If there is no
reaction, then it is cross match compatible and the blood
is reserved for that patient.

64

Why would someone need irradiated blood as a transfusion?

If they have depressed T cell function, eg post bone marrow transplant, di George, Hodgkin lymphoma, leukaemia, AIDS, certain drugs (fludarabine)

65

What are the special request blood transusions available?

Irradiated
CMV negative - immunocompromised
Specific phenotypes (Rh and Kell)
Washed
Plasma depleted
T antigen negative

66

What are the two types of transfusion reaction?

Immune
Non-immune

67

How can the immune transfusion reactions be subdivided?

Acute
Delayed

68

What is haptoglobin?

Haptoglobin binds free Hb released from erythrocytes with high affinity and thereby inhibits its oxidative activity. The haptoglobin-hemoglobin complex will then be removed by the reticuloendothelial system (mostly the spleen). Haptoglobulin assay is used to screen for and monitor intravascular hemolytic anemia.

69

What might you see on a blood film in a haemolytic anaemia or splenomegaly?

Reticulocytes - distinguishable by the small amount of DNA that will be left in the cell.

70

What are the main symptoms of an acute haemolytic transfusion reaction?

Chills
Fever
Jaundice
Hypotension
Tachycardia
Pain in chest and lumbar region
Haemoglobinuria
Hyperbilirubinemia

71

How would you manage someone who is having an acute haemolytic transfusion reaction?

Urgent medical review (possibly ITU)
Stop transfusion
IV fluids
Take obs
Haemoflitration - red cell exchange
Oxygen high flow
Steroids (+/- adrenaline)
Possibly antiobiotics

72

What are the clinical features of transfusion related acute lung injury?

Pulmonary capillary leakage leads to pulmonary oedema and acute hypoxia (without heart failure)
Occurs within 4 hours of a blood transfusion
Mortality of 30-50%
Not easily distinguished from ARDS

73

How long after blood transfusion does post transfusion purpura present?

5-12 days

74

Does post-transfusion purpura most often affect males or females?

Females

75

What is the underlying cause of post-transfusion purpura?

Platelet specific alloantibodies causing an immune mediated thrombocytopenia.

76

What are the main symptoms of post-transfusion purpura?

Bleeding
Bruising

77

How is post-transfusion purpura managed?

It is usually self limiting but may require IVIg. Plasmapheresis is also an option.
Important to exclude donor from further blood donations.

78

What is the underlying pathology of transfusion associated graft versus host disease (TA-GvHD)?

Immune reaction of donor T cells against
the recipient. The recipient is often immunodeficient.

79

How long after transfusion does transfusion associated graft versus host disease (TA-GvHD) usually present?

Can be anything from 4 days to 6 weeks

80

What are the signs and symptoms associated with transfusion associated graft versus host disease (TA-GvHD)?

Fever
Skin rash
Pancytopenia
Liver failure
Renal failure

81

What is the mortality rate of someone with transfusion associated graft versus host disease (TA-GvHD)?

75-90% - There is no effective treatment

82

How long after infusion will signs and symptoms of transfusion associated infective shock present?

During the transfusion
Usually during the transfusion of the first 100mls

83

What are the non-immune causes of acquired haemolytic anaemia?

Hypersplenism
Infections
Trauma - such as burns
Lead poisoning
Paroxysmal nocturnal haemoglobinuria
Renal disease
Liver disease

84

What are the clinical features of haemolysis?

Jaundice - unconjugated hyperbilirubinaemia
Anaemia
Reticulocytosis
Macrocytosis
Morphological changes - spherocytes, fragmented cells
Marrow hypertrophy and hyperplasia

85

What is the test used to detect haemoglobin-albumin complex?

Schumms test

86

Infections by which organisms do people who are iron overloaded tend to get?

Gram negative bacteria