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Path Y > Haematology - Blood Transfusion 1 & 2 > Flashcards

Haematology - Blood Transfusion 1 & 2 Flashcards

1
Q

Recall 2 ways in which patients’ blood group is tested

A
  1. Using anti-A,B and O reagents against the patient’s red blood cells
  2. Also use ‘reverse group’ - known A and B group RBCs against the patient’s plasma

The forward grouping suggests the presence or absence of A and B antigens in RBCs, whereas reverse grouping indicates the presence or absences of anti-A and anti-B in serum.

o A positive result causes agglutination at the top
o A negative result will mean that the red cells stay suspended at the bottom of the vial
. The subject is blood group A if agglutination occurred with the Anti-A test serum; group B if agglutination occurred with the Anti-B test serum; group AB if agglutination occurred with both test serums, and O if there was no agglutination in either case

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2
Q

What is the purpose of ‘immediate spin’ blood testing?

A

Used in emergencies only
Incubation for just 5 minutes
Determines ABO compatibility only

An immediate spin crossmatch is performed using patient’s plasma or serum and donor red cells. The purpose is to demonstrate or confirm ABO compatibility.

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3
Q

What are the 3 pillars of patient blood management?

A
  1. Optomise haematopoiesis
  2. Reduce bleeding (eg stop anti-platelt drugs, cell-salvage techniques)
  3. Harness and optomise physiological tolerance of anaemia
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4
Q

For which blood products is D compatibility required?

A

Red cells and platelets (but not FFP or cryoprecipitate)

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5
Q

What is the storage temperature of red cells, platelets, FFP and cryoprecipitate?

A

Red cells: 4 degrees C
Platelets: 20 degrees C
FFP: 4 degrees C once thawed (-30c frozen before)
Cryoprecipitate: Room temp once thawed (before -30c frozen)

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6
Q

What is the storage length of red cells, platelets, FFP and cryoprecipitate?

A

Red cells: 35 days
Platelets: 7 days
FFP: 24 hours thawed othwerise 3 years frozen
Cryoprecipitate: 4 hours thawed otherwise 3 years frozen

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7
Q

What is the transfusion rate of red cells, platelets, FFP and cryoprecipitate?

A

Red cells: 1 unit over 2-3 hours
Platelets: 1 unit over 20-30 mins
FFP: 1 unit over 20-30 mins
Cryoprecipitate: 1 unit over 20-30 mins

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8
Q

How much blood loss counts as ‘major’?

A

>30% blood volume lost

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9
Q

When are platelets contra-indicated?

A

TTP/ heparin-induced TTP

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10
Q

How low does haemaglobin need to be to require transfusion peri-operatively vs post-chemo?

A

Peri-op/ crit care: <70g/dL
Post-chemo: <80g/dL

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11
Q

In what type of surgery is post-operative cell salvage most often done?

A

Knee surgery

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12
Q

What are the steps of intra-operative cell salvage?

A

Centrifuge, filter, wash and re-infuse blood

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13
Q

What special blood reuquirements do pregnant women & neonates have?

A

CMV neg

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14
Q

What special blood reuquirements do highly immunocompromised patients have?

A

Blood needs to be irradiated

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15
Q

What special blood requirements do patients who have had severe reactions in the past to transfusion have?

A

Washed cells e.g in IgA deficiency
to reduce allergic reactions due to contaminating plasma proteins

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16
Q

Recall the 10 classes of transfusion reaction, and which are acute/ delayed?

A

Acute (<24 hours):

  1. Acute haemolytic (ABO incompatible)
  2. Allergic/ anaphylaxis
  3. Bacterial infection
  4. Febrile non-haemolytic
  5. TACO/TRALI (Resp)

Delayed: over 24 hours - may pass dark urine or be jaundiced

  1. Delayed haemolytic transfusion reaction (antibodies)
  2. Transfusion-associated GVHD
  3. Infection (malaria, CJD)
  4. Post-transfusion purpura
  5. Iron overload (thalasaemia patients mostly)
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17
Q

What monitoring should be done during a blood transfusion as minimum?

A
  1. Baseline temp, HR, RR, BP
  2. Repeat obs after 15 mins
  3. Repeat hourly after end of transfusion
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18
Q

What are the features of febrile non-haemolytic transfusion reaction?

A

Temp increase by 1 degree ish
Chills and rigors

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19
Q

Why is febrile non-haemolytic transfusion reaction rare nowadays?

A

Blood is now leucodepleted to reduce risk of febrile non-haemolytic transfusion reaction

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20
Q

How should febrile non-haemolytic transfusion reaction be managed?

A

Stop/ slow the transfusion and give paracetamol

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21
Q

What is the pathophysiology of febrile non-haemolytic transfusion reaction?

A

Cytokines released by white blood cells during storage cause a febrile reaction upon transfusion

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22
Q

What should be the management of an allergic transfusion reaction?

A

Stop/ slow transfusion
IV antihitamines

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23
Q

What are the symptoms of ABO incompatibility?

A

Shock and fever
Restlessness, fever, vomiting and collapse
=severe/fatal

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24
Q

What is the appropriate management for ABO incompatibility?

A

Stop transfusion
Check patient and component
Repeat cross match and DAT

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25
Q

What are the symptoms of bacterial contamination of blood?

A

Presents very similar to wrong blood - shock, increased temp, restless, fever, vomiting, collapse
=severe/fatall

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26
Q

How does bacterial contamination of blood cause symptoms?

A

Bacterial growth –> endotoxin which causes immediate collapse

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27
Q

Recall some protocols for prevention of bacterial contamination of blood

A

Donor questionning
Arm cleaning
Diversion of first 20mls of blood into pouch for testing
Proper storage

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28
Q

Which patients are at most risk of anaphylactic reaction to a blood transfusion?

A

Those with IgA deficiency (remember its common, 1 in 600)

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29
Q

How quickly does TACO/TRALI present?

A

Within 6 hours

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30
Q

What does TACO stand for?

A

Transfusion-associated circulatory overload

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31
Q

What are the symptons of TACO?

A

SOB, decreased SaO2, increased HR and BP (due to pulmonary oedema)
clinical fluid overload

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32
Q

What should be checked pre-transfusion to reduce the risk of TACO?

A

Check the patient is not always in positive fluid balance
Check they don’t have risk factors for TACO = renal impairment, cardiac failure, hypoalbuminaemia - if they do, they need a aprophylactic diuretic

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33
Q

What is the probably cause of TRALI?

A

donor dervied Antibodies

34
Q

What is the main difference in the management of TACO and TRALI?

A

TRALI doesn’t repsond to diuretics like furosemide

35
Q

What is the pathophysiology of delayed haemolytic transfusion reaction?

A

Development of an ‘immune’ antibody to a RBC antigen they lack (‘allo-immunisation’)
further transfusions will cause antibodies to lyse RBCs = extravascular haemolysis

36
Q

Over what time period does delayed haemolytic transfusion reaction develop?

A

5-10 days (IgG mediated)

37
Q

Recall 2 clinical features of delayed haemolytic transfusion reaction

A

DAT positive
Jaundiced

o High bilirubin Low Hb
o High reticulocytes Haemoglobinuria over a few days

38
Q

What is the prognosis of transfusion-associated GVHD?

A

Always fatal

39
Q

Which patients are most at risk of transfusion-associated GVHD?

A

Severely immunosuppressed

40
Q

What is the cause of transfusion-associated GVHD?

A

Failure to destroy donor lymphocytes completely

41
Q

How can transfusion-associated GVHD be prevented?

A

Irradiate blood for immunosuppressed patients

42
Q

What are 4 symptoms of transfusion-associated GVHD?

A

Severe diarrhoea
Liver failure
Skin desquamation
Bone marrow failure

43
Q

How long after a transfusion do post-transfusion purpura present?

A

7-10 days

44
Q

How should post-transfusion purpura be treated?

A

IV Ig

45
Q

What is the main complication risk of post-transfusion purpura?

A

Big bleeding

46
Q

How can iron overload be prevented?

A

Chelation (Exjade)
e.g in thalassemia patients who’ve had lots of transfusions

47
Q

When are pregnant women checked for RBC Immunoglobins during pregnancy, to prevent GVHD?

A

12 and 28w gestation

48
Q

What is the anti-D dosing during pregnancy for sensitsing events?

A

Before 20w, 250iu
After 20w, minimum 500iu

49
Q

How does anti-D work during pregnancy to prevent GVHD?

A

RhD pos foetal cells get covered in anti-D Ig
Mother’s reticulo-endothelial system removes coated cells (spleen) before they get chance to sensitise mother

50
Q

How quickly must anti-D be given following sensitisation events?

A

Within 72 hours

51
Q

Recall some examples of sensitising events

A

Spontaneous miscarriages
Amniocentesis/ CVS
Abdominal trauma
External cephalic version
Still birth

52
Q

What is the routine anti-D prophylaxis for mother’s with no obvious sensitising events?

A

1500iu anti-D at 28-30w gestation
or • 2 smaller doses (500, 500 IU) at 28w and 34w

53
Q

what % of population are Rh +ve

A

 85% population are RhD +ve; 15% RhD -ve

54
Q

2 factors that determine ABO blood group

A

antigens on RBC membrane & naturally occurring IgM in the plasma
 IgG reacts against atypical RBC antigens
 IgM reacts against normal RBC antigens

55
Q

anti-D antibodies cause what type of reaction

A

they are IgG & they cause a delayed haemolytic transfusion reaction
do not cause direct agglutination of RBCs or an immediate haemolytic

56
Q

Anti-D made by an Rh -ve mother exposed to Rh +ve blood causes what

A

haemolytic disease of the newborn or severe fetal anaemia and heart-failure (hydrops fetalis)

57
Q

distinguish between cross match and group and save

A

GROUP and SCREEN – check ABO group and plasma antibodies in patient
Full crossmatch – checks patient’s blood against donor blood specifically

58
Q

does cross match use IAT or DAT

A

IAT

59
Q

distinguish between IAT and DAT

A

The direct test looks for antibodies that are stuck to red blood cells.
The indirect test looks for antibodies floating in the liquid part of your blood, called serum.

60
Q

do platelets have D antigens

A

Platelets do not express Rh antigens but contain small numbers of RBCs or fragments, which can cause alloimmunization to red cell antigens, including the RhD antigen when platelets obtained from RhD-positive donors are transfused to RhD-negative recipients.

61
Q

why may platelets transfusion be higher risk of infection compred to plasma

A 
platelets = room temp, bacteria may grow so give quickly 
plasma = frozen, more likely to be an allergic reaction
62
Q

3 indications for FFP transfusion

A

blood loss over 150ml/min
DIC WITH bleeding
liver disease (PT over 1.5x normal)

63
Q

2 indications for platelet transfusion

A

prevent bleeding after surgery or chemo
patients with thrombocytopenia who are bleeding

64
Q

who is cell salvage useful in?

A

in people with rare blood groups and Jehovah’s witnesses

65
Q

what should be crossmatched and what shouldn’t

A
  • Red cells are crossmatched serologically or electronically
  • Platelets and FFP are not crossmatched but the right group should be selected
66
Q

what’s the most common acute reaction to blood transfusion

A

TACO

67
Q

ABO incompatibility is mediated by what Ig

A

IgE

68
Q

differences between TACO and TRALI

A

• TACO responds to diuretics immediately (and has raised JVP);
TRALI does NOT respond to diuretics (no JVP), may also have fever

69
Q

TRALI commonly occur sin the transfusion of what? therefore how can it be prevented

A

(more common in FFP or platelet transfusion
Prevention = use male donors for plasma and platelets (no pregnancy or previous transfusions, so no HLA/HNA ABs)

70
Q

DHTR is caused by what antibodies

A

precipitated by re-exposure to a non-ABO red cell antigen

= duffy and Kidd antigens

71
Q

anti A and anti B are what type of antibodies

A

IgM

72
Q

anti duffy, Kidd and Rh are what type of antibodies

A

IgG

73
Q

what infection excludes you from being a donor

A

Variant CJD

74
Q

what reaction is always fatal and why

A

Transfusion Associated Graft-Versus-Host Disease (TaGVHD)

o Donor’s blood will contain some lymphocytes that are able to divide
o Normally, the patient’s immune system will recognises these donor lymphocytes as foreign and destroy them
o In susceptible patients (very immunosuppressed), these lymphocytes are NOT destroyed
o Lymphocytes recognise patient’s tissue HLA antigens as foreign and attack (gut, liver, skin and bone marrow)

75
Q

give 2 features of graft versus host

A

BM failure
skin desquamation

76
Q

what antibody is associated w post transfusion purpura

A

Human Platelet Antigen (HPA) 1a -ve patients

77
Q

what is the mechanism of haemolytic disease of the newborn

A

o In pregnancy, the first RhD-positive foetus will not experience any issues, however, they will stimulate the development of anti-D antibodies in the mother  in a subsequent pregnancy, if the mother has another RhD-positive foetus, the antibodies will destroy foetal red cells leading to severe anaemia ± HDN (jaundice too)xfsensiti

78
Q

what antibodies can cross the placenta

A

IgG

79
Q

outline the genetics of Rhesus

A

If the father is heterozygous for the RHD deletion, there is a 50% chance of the foetus being D-negative, in which case the pregnancy essentially free of any haematological risk. If the father is homozygous for the RHD gene, the foetus will definitely inherit the D antigen, which could influence the couple’s decision on whether to have a child or not.

If the father is heterozygous for the RHD deletion, there is a 50% chance of the foetus being D-negative, in which case the pregnancy essentially free of any haematological risk. If the father is homozygous for the RHD gene, the foetus will definitely inherit the D antigen, which could influence the couple’s decision on whether to have a child or not.
o Check ffDNA sample from maternal blood (allows identification of the baby’s RhD group) – if baby is RhD -ve, there’s no problem

80
Q

when does rhesus disease occur

A

Rhesus disease only happens when the mother has rhesus negative blood (RhD negative) and the baby in her womb has rhesus positive blood (RhD positive).

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