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HAEM - Abbie > 7. Blood transfusion I > Flashcards

7. Blood transfusion I Flashcards

1
Q

What are ABO groups determined by?

A

a) by the antigens (sugars) on the red cell membrane

b) the naturally-occurring antibodies (IgM) in the plasma

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2
Q

What happens if you give ABO incompatible blood transfusion?

A

It will cause a massive intravascular haemolysis and this is potentially fatal

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3
Q

Red cells which carry the RhD antigen are ‘RhD positive’. What blood can these patients receive?

A

These patients can receive RhD negative (just a waste!) or RhD positive red cells

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4
Q

RhD negative lack the RhD antigen. What happens if you give RhD positive red cells?

A

These patients can make immune anti-D if exposed to RhD postive red cells. Immune anti-D antibodies are IgG, which do not cause direct agglutination of RBCs so not immediate haemolysis and death but delayed haemolytic transfusion and reaction.

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5
Q

What are some other Rh antigens and other blood group antigens?

A

Rh antigens: C, c, E, e. Blood group antigens: Kell (K), M, N, S, Duffy (Fy), Kidd (Jk). But we only match for these if patient has corresponding antibody (or occasionally in certain othe rsituations)

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6
Q

What causes a delayed haemolytic transfusion reaction?

A

If someone who is RhD-negative is given RhD-positive blood

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7
Q

Apart from RhD, what other blood group antigens cause delayed haemolytic transfusion?

A

Duffy and Kidd are notorious for causing delayed haemolytic transfusion reactions

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8
Q

Why is it important to test for Duffy (Fy) and Kidd (Jk)?

A

Antibodies against Duffy and Kidd wane over time so they may test negative for these antibodies when they present in the future needing another transfusion

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9
Q

What happens when you give RhD positive blood to an RhD negative patient for the first time?

A

Giving RhD positive blood to an RhD negative patient for the first time will NOT cause any acute reaction but anti-D antibodies will be detected the next time that they need a blood transfusion

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10
Q

What is a potential complication in RhD negative mothers?

A

Anti-D antibodies produced by a mother carrying an RhD positive foetus can cause haemolytic disease of the newborn or severe foetal anaemia and heart failure (hydrops fetalis)

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11
Q

What can be given when there is a RhD incompatibility between the mother and foetus?

A

Prophylactic anti-D immunogloblin can be given when there is an incompatibility between the mother and the foetus

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12
Q

Describe testing before transfusion

A

Use known anti-A, anti-B and anti-D reagents against the patient’s red blood cells. Reverse group: known A and B groups red blood cells are mixed with the patient’s plasma (IgM antibodies). A positive result causes agglutination at the top. A negative result will mean that the red cells stay suspended at the bottom of the vial.

A blood group is done BEFORE EVERY TRANSFUSION, even if it has been done many times before.

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13
Q

Example: There is agglutination with anti-B and anti-1 cells. There is no reaction with anti-A, anti-D or B cells. What is the patient’s blood group?

A

This patient’s blood group is B-

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14
Q

NOTE: it is impossible to test for all other RBC antigens because there are hundreds of them. 1-3% of patients have developed antibodies to one or more RBC antigens. How may these have been developed?

A

These may have been developed due to previous transfusion or pregnancy

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15
Q

What class are immune antibodies?

A

IgG

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16
Q

How can we prevent delayed haemolytic transfusion reactions?

A

We MUST identify all clinically significant antibodies in the patient’s serum and transfuse RBCs that are negative for those antigens. This will prevent delayed haemolytic transfusion reactions.

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17
Q

Describe how antibody screen on patient’s plasma/ group and screen is done:

A
  • Recipient’s serum is obtained, containing antibodies
  • Use 2 or 3 reagent red cells that contain ALL the important red cell antigens between them.
  • Donor’s blood sample is added to the tube with serum.
  • Recipient Ig’s that target the donor’s red blood cells form antibody-antigen complexes.
  • Anti-human Ig’s (Coombs antibodies) are added to the solution.
  • Screen is done by incubating the patient’s plasma and screening cells using indirect antiglobulin technique.
  • This allows bridging of red cells coated by IgG which would otherwise not be able to bridge themselves between two cells - this forms a visible clump.
  • Agglutination of red blood cells occurs, because human Ig’s are attached to red blood cells.
  • This process is automated
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18
Q

How is blood issued?

A

Donor RBCs are labelled with ABO and D type. They are also labelled with other Rh antigens and K. Select K-negative blood for females of childbearing potential

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19
Q

Summarise how full crossmatch is done

A
  • Uses IAT (indirect antiglobulin test or indirect Coombe’s test).
  • Patient’s plasma is incubated with donor red cells at 37 degrees for 30-40 mins
  • This detects an antibody-antigen reaction that could destroy the red cells leading to extravascular haemolysis
  • Add antiglobulin reagent to cause cross-linking
  • IgG antibodies can bind to RBCs but do not crosslink which is why the antiglobulin reagent must be added
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20
Q

Summarise how immediate spin is done

A

Incubate patients plasma and donor red cells for 5 minutes only and spin. Will only detect ABO incompatibility. This is used in emergencies. IgM anti-A and/or anti-B bind to RBCs, fix complement and lyse the cell.

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21
Q

Summarise how electronic crossmatch is done

A

There is an electronic crossmatch (electronic issue (EI)) where compatibility is determined by an IT system without physical testing of donor cells against plasma. This is a quick process, requiring fewer staff which allows better stock management.

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22
Q

What are the different types of serological crossmatch?

A

Full crossmatch, immediate spin and electronic crossmatch

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23
Q

What are key things to consider with regards to patient information and consent?

A

Valid consent is required (verbal and written). Alternatives should be offered if appropriate. If transfused in an emergency, the patient must be informed afterwards. Involve patients in the process (there may be special requirements like irradiated components - this is usually haematology patients).

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24
Q

What are the records kept on the components of blood?

A

All components are issued on a named patient bases. 100% of components must be traceable from the donor to the recipient. Records are kept for 30 years.

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25
Q

What red cells are given in an emergency?

A

Give ABO/D compatible group O -ve in emergency. Consider special requirements.

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26
Q

How are red cells stored?

A

Stored at 4 degrees C for 35 days. Must be transfused within 4 hours of leaving fridge. If the blood is unused and returned to the lab within 30 mins it can be put back in the fridge.

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27
Q

How much and over how long should RBC be transfused?

A

Transfuse 1 unit RBC over 2-3 hours

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28
Q

What platelets should be given in an emergency?

A

Platelets do not need to be crossmatched because the antigens are weakly expressed. Should be D compatible; no need to cross match. Consider special requirements.

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29
Q

If group O is given to A, B or AB patients, what should you do?

A

Select ‘high-titre’ negative antibodies (i.e. low anti-A/B antibodies)

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30
Q

How are platelets stored?

A

Stored at 22 degrees C for 7 days

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31
Q

What plasma should be given in an emergency?

A

Give ABO compatible but D group does not matter

32
Q

What is the universal donor for RBC?

A

Group O-

33
Q

What is the universal donor for plasma?

A

AB (because they have no antibodies)

34
Q

Why do platelets need to be given more quickly?

A

Because they are stored at room temperature and so bacteria can contaminate it quite quickly

35
Q

What should be done if a patient develops a temperature whilst receiving platelets?

A

Stop the platelets and take cultures to check whether the patient is septic. The platelets should be sent back to the lab for microbiological testing.

36
Q

What is a reaction with plasma more likely to be caused by?

A

A reaction with plasma is more likely to be allergic because plasma is frozen and so is unlikely to be contaminated by microbes

37
Q

What are indications for transfusion of red cells?

A

Major blood loss, peri-op, critical care, post chemo and symptomatic anaemia - ischaemic heart disease, breathless, ECG changes

38
Q

What is the trigger for transfusion of red cells in major blood loss?

A

If >30% blood volume lost

39
Q

What is the trigger for transfusion of red cells in peri-op, critical care?

A

Hb <70g/L vs 80g/L

40
Q

What is the trigger for transfusion of red cells in post chemo?

A

Hb < 80g/L

41
Q

What are the triggers for transfusion of red cells in symptomatic anaemia?

A

Ischaemic heart disease, breathless, ECG changes

42
Q

When should Hb be checked in a transfusion?

A

Check Hb before transfusion and after every 1-2 units

43
Q

What increase in Hb should 1 unit of RBC cause in a patient?

A

1 unit RBC should cause a 10 g/L increase in Hb in a 70-80 kg patient

44
Q

Transfusion above what g/L is rarely required?

A

100g/L

45
Q

What is the purpose of Maximum Surgical Blood Ordering Schedule (MSBOS)?

A
  • Based on negotiation between surgeons and transfusion lab about predictable blood loss for planned surgery.
  • Some operations rarely need blood whereas others will always need blood (e.g. AAA repair).
  • For elective surgery, the patient should be group and screened before the operation.
  • If no antibodies are present, a crossmatch is NOT needed but the sample should be saved in the fridge.
  • If there is an unexpected need for blood, this can be provided within 10 mins (by electronic issue as no antibodies are present).
  • If antibodies are present, ALWAYS CROSSMATCH.
46
Q

What is pre-operative autologous deposit?

A

A technique where you own blood is donated before a planned operation. This is NOT done in the UK.

47
Q

What is intra-operative cell salvage?

A

Blood is collected during surgery, it is then centrifuged, filtered and washed before being reinfused. This is available in the UK.

48
Q

What is post-operative cell salvage?

A

Collect blood that is lost post-operatively into a wound drain. This is filtered and re-infused. Mainly done for orthopaedic operations (e.g. knee surgery).

49
Q

Who is cell salvage useful in?

A

Cell salvage is useful in people with rare blood groups and Jehovah’s witnesses. NOTE: all the coagulation factors and platelets are removed from cell salvage blood.

50
Q

When is CMV negative blood required?

A

Required for intra-uterine and neonatal transfusions. Also used for elective transfusion in pregnant women

51
Q

When is irradiated blood required?

A

Required for highly immunosuppressed patients. This is because these patients cannot destroy incoming donor lymphocytes. The presence of these lymphocytes can cause fatal transfusion-associated graft-versus-host disease (TA-GvHD).

52
Q

When is washed transfusion required?

A

Red cells and platelets are given to patients who have had severe allergic reactions to some donors’ plasma proteins. This takes 4 hours to happen so needs to be pre-planned. Another group who may have severe allergic reactions are IgA deficient patients.

53
Q

What are triggers for transfusion of platelets?

A

Massive transfusion, prevent bleeding (post chemo), prevent bleeding (surgery), platelet dysfunction or immune cause - only if active bleeding

54
Q

What is a trigger for transfusion of platelets in massive transfusion?

A

Aim for platelets > 75 x 10^9/L

55
Q

What is a trigger for transfusion of platelets to prevent bleeding (post chemo)

A

If < 10x10^9/L (<20 if sepsis)

56
Q

What is a trigger for transfusion of platelets to prevent bleeding (surgery)?

A

< 50 x10^9/L (<100 if critical site: eye, CNS)

57
Q

What is a trigger for transfusion of platelets in platelet dysfunction or immune cause?

A

Only if active bleeding

58
Q

What are contraindications for platelet transfusion?

A

Heparin-induced thrombocytopaenia and thrombosis, thrombotic thrombocytopaenic purpura (TTP)

59
Q

What is the rise in platelet count when 1 unit of platelets (adult treatment dose) is given?

A

Usually raises platelet count by 30-40 x 109/L

60
Q

What is platelet dysfunction caused by?

A

Drugs e.g. aspirin, clopidogrel

61
Q

What are indications for transfusion of fresh frozen plasma?

A

Massive transfusion, disseminated intravascular coagulopathy (DIC), liver disease+ risk, rarely - coagulation factor replacement where factor concentrate not available

62
Q

What is the trigger for transfusion of FFP in massive transfusion?

A

Blood loss > 150ml/min

63
Q

What is the trigger for transfusion of FFP in disseminated intravascular coagulopathy?

A

DIC with bleeding

64
Q

What is the trigger for transfusion of FFP in liver disease and risk?

A

PT ratio > 1.5x normal

65
Q

What is trigger for transfusion of FFP in coagulation factor replacement?

A

Rarely - coagulation factor replacement where factor concentrate is not available

66
Q

Which clotting factors does FFP contain?

A

All clotting factors

67
Q

What is the adult dose of FFP?

A

15ml/kg

68
Q

How many mL does 1 unit of FFP contain?

A

250mL

69
Q

Is FFP the treatment of choice to reverse warfarin?

A

No. FFP is NOT the treatment of choice to reverse warfarin

70
Q

What is a better treatment to reverse warfarin (than FFP)?

A

A better treatment is PCC (prothombin complex concentrate). This contains factors 2, 7, 9 and 10.

71
Q

Who is involved in the care of a patient undergoing blood transfusion?

A

Nurse doctor, porter nurse, biomedical scientist, phlebotomist, doctor

72
Q

What are the responsibilities of a nurse doctor in the transfusion process?

A

Care of the patient during the transfusion, checking the blood and starting transfusion

73
Q

What are the responsibilities of a porter nurse in the transfusion process?

A

Collecting the blood and delivering to the clinical area

74
Q

What are the responsibilities of a biomedical scientist in the transfusion process?

A

Testing the blood group and crossmatching the blood

75
Q

What are the responsibilities of a phlebotomist/nurse doctor in the transfusion process?

A

Taking a blood sample and compatibility testing

76
Q

What are the responsibilities of a doctor in the transfusion process?

A

Ordering and prescribing blood, documenting the transfusion

77
Q

List/summarise six things to remember in a transfusion

A
  1. Make sure you HANDWRITE the bottle.
  2. When a pack of blood is issued, it will have a tag on it with all the patient’s details on it.
  3. Group and save before every transfusion.
  4. Platelets and FFP are not crossmatched but the right group should be selected.
  5. Remember the special requirements.
  6. Make the right transfusion decision for every patient individually - sometimes that can mean no transfusion.

HAEM - Abbie (16 decks)

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