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Pathology ICSM COPY > Haematology 14 - Blood Transfusion 1 & 2 > Flashcards

Haematology 14 - Blood Transfusion 1 & 2 Flashcards

(75 cards)

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1
Q

Outline which Abs and Ags are present in groups A/B/AB/O

A
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2
Q

What subtype of antibody determines ABO group?

A

IgM Abs in plasma - reacts against normal RBC Ags

(IgG against atypical RBC Ags)

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3
Q

What happens if you give ABO incompatible blood?

A

massive intravascular haemolysis → fatal

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4
Q

Which blood type can RhD + or - receive?

A
  • RhD +ve (85%) - RhD positive and RhD negative (but waste)
  • RhD -ve (15%) - RhD neg ONLY
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5
Q

What happens if you give RhD pos blood to RhD neg pt?

A

make anti-D Abs (IgG)

delayed haemolytic transfusion (NOT direct agglutination so not immediate haemolysis)

IgG - cause a DELAYED transfusion reaction; extravascular haemolysis

As opposed to naturally occurring IgM antibodies (that cause an IMMEDIATE intravascular haemolysis)

will be picked up by the lab next time they need blood

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6
Q

What happens if RhD + blood is given to RhD - mother ?

A

→ HDN or severe foetal anaemia and heart failure (hydrops fetalis)

IgG can cross placenta

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7
Q

Group and screen vs full crossmatch

A

GROUP and SCREEN– check ABO group and plasma antibodies in patient

Full crossmatch– checks patient’s blood against donor blood specifically

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8
Q

Recall 2 ways in which patients’ blood group is tested

A
  1. ‘forward group’ - known anti-A,B and O reagents against patient’s RBCs
  2. ‘reverse group’ - known A and B group RBCs against the patient’s plasma (IgM Abs)
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9
Q

Describe the process of antibody testing of blood

A

Group and screen

  • Use 2 or 3 reagent RBCs containing all important RBC Ags
  • Then incubate the patient’s plasma using the indirect antiglobulin technique (IAT)

Anti-Human Globulin (AHG) promotes agglutination -bridges RBCs coated by IgG (which can’t themselves bridge 2 RBCs)

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10
Q

How is IAT technique used in full crossmatching?

A

patient plasma incubated with donor RBCs

detects Ab-Ag reaction → destroys RBCs → extravasc haemolysis

Add antiglobulin reagent to promote cross-linking

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11
Q

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

A

Full cross match

Used in emergencies only

Incubation for just 5 minutes
Determines ABO compatibility only

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12
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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13
Q

For which blood products is D compatibility required?

A

Red cells and platelets (but not FFP or cryoprecipitate)

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14
Q

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

A

Red cells: 4 degrees C
Platelets: 20 degrees C
FFP: frozen - 4 degrees C once thawed
Cryoprecipitate: Room temp once thawed

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15
Q

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

A

Red cells: 35 days
Platelets: 7 days
FFP: 24 hours
Cryoprecipitate: 4 hours

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16
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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17
Q

Why must platelets be given quicky?

A

stored at room temp so bacteria can contaminate it quickly

if pt fever → stop platelets and culture

send platelets back to lab for microbiological testing

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18
Q

what type of reaction if more likey with plasma transfusion?

A

allergic - plasma frozen so unlikely to be contaminated by microbes

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19
Q

How much blood loss counts as ‘major’?

A

>30% blood volume lost

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20
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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21
Q

Indications for RBC transfusion

A
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22
Q

When are platelets contra-indicated?

A

TTP/ heparin-induced TTP

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23
Q

Indications for platelet transfusion

A
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24
Q

When is FFP indicated?

A

Contains all the clotting factors

Adult dose = 15 mL/kg (1 unit of FFP contains 250 mL à enough for 16.6kg)

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25
What is the transfusion product of choice for warfarin reversal?
PCC(prothrombin complex concentrate) This contains factors 2, 7, 9 and 10
26
What does cryoprecipirate contain?
27
In what type of surgery is post-operative cell salvage most often done?
Mainly done for orthopaedic operations (e.g. knee surgery) NOTE: all the coagulation factors and platelets are removed from cell salvage blood useful in people with rare blood groups and Jehovah's witnesses
28
What special blood reuquirements do pregnant women have?
CMV neg
29
What special blood reuquirements do highly immunocompromised patients have?
Blood needs to be irradiated As patients cannot destroy incoming donor lymphocytes Presence of these lymphocytes → fatal transfusion-associated graft-versus-host disease (TA-GvHD)
30
What special blood requirements do patients who have had severe reactions in the past to transfusion have?
Washed cells
31
Recall the 10 classes of transfusion reaction, and which are acute/ delayed?
Acute (\<24 hours): 1. Acute haemolytic (ABO incompatible) 2. Allergic/ anaphylaxis 3. Bacterial infection 4. Febrile non-haemolytic 5. TACO/TRALI Delayed: 6. Delayed haemolytic transfusion reaction (antibodies) 7. Transfusion-associated GVHD 8. Infection (malaria, CJD) 9. Post-transfusion purpura 10. Iron overload (thalasaemia patients mostly)
32
What monitoring should be done during a blood transfusion as minimum?
1. Baseline temp, HR, RR, BP 2. Repeat obs after 15 mins 3. Repeat hourly after end of transfusion
33
s/s of acute transfusion reaction
Fever Rigors Flushing Vomiting Dyspnoea Pain at transfusion site Loin pain/chest pain Urticaria Itching Headache Collapse
34
What are the features of febrile non-haemolytic transfusion reaction?
Temp increase \>1% Chills and rigors
35
Why is febrile non-haemolytic transfusion reaction rare nowadays?
Blood is now leucodepleted to reduce risk of febrile non-haemolytic transfusion reaction
36
How should febrile non-haemolytic transfusion reaction be managed?
Stop/ slow the transfusion and give paracetamol
37
What is the pathophysiology of febrile non-haemolytic transfusion reaction?
Cytokines released by white blood cells during storage cause a febrile reaction upon transfusion during/soon after transfusion (blood/platelets)
38
What should be the management of an allergic transfusion reaction?
Stop/ slow transfusion IV antihitamines
39
presentation of allergic transfusion reaction
mild urticarial or itchy rash sometimes with a wheeze
40
What are the symptoms of ABO incompatibility?
General: restless, chest/loin pain, fever, vomiting, flushing, collapse, haemoglobinuria (later) Monitoring: ↓ BP, ↑ HR, ↑ Temperature
41
What is the appropriate management for ABO incompatibility?
Stop transfusion Check patient and component Repeat cross match and DAT
42
What are the symptoms of bacterial contamination of blood?
Presents very similar to wrong blood - shock, increased temp, restless, fever, vomiting, collapse
43
How does bacterial contamination of blood cause symptoms?
Bacterial growth --\> endotoxin which causes immediate collapse
44
Recall some protocols for prevention of bacterial contamination of blood
Donor questionning Arm cleaning Diversion of first 20mls of blood Proper storage
45
Which patients are at most risk of anaphylactic reaction to a blood transfusion?
Those with IgA deficiency anti-IgA antibodies develop in response to exposure to IgA in donor blood Only a minority go on to have a severe transfusion reaction
46
How quickly does TACO/TRALI present?
Within 6 hours
47
What does TACO stand for?
Transfusion-associated circulatory overload most common pulmonary complication of transfusion
48
What are the symptons of TACO?
**pulmonary oedema/fluid overload** SOB, ↓SpO2 saturations Fluid overload ↑ HR ↑ BP
49
What is TACO caused by?
lack of attention to fluid balance – especially in… HF, renal impairment, hypoalbuminaemia, very young/old
50
What should be checked pre-transfusion to reduce the risk of TACO?
Check the patient is not always in positive fluid balance Check they don't have risk factors for TACO - cardiac/liver/kidney disease, oedema etc if they do, they need a aprophylactic diuretic
51
What is the probable cause of TRALI?
Anti-WBC Ab in donor blood interact w/ pt WBCs Aggregates WBCs stick to pulmonary capillaries → release neutrophil proteolytic enzymes and toxic O2 metabolites lung damage (incompletely understood)
52
S/s of TRALI
ARDS NO FLUID OVERLOAD (not respond to diuretics) SoB, ↓spO2, fever ↑ HR ↑ BP CXR - bilateral pulmonary infiltrates during/within 6 hours of transfusion due to circulatory overload and other causes
53
What is the main difference in the management of TACO and TRALI?
TACO responds to diuretics immediately (and has raised JVP); TRALI does NOT respond to diuretics (no JVP)
54
What is the pathophysiology of delayed haemolytic transfusion reaction?
Development of an 'immune' antibody against RBC antigen they lack ('allo-immunisation') Further transfusions → antibodies lyse RBCs (extravascular haemolysis)
55
Over what time period does delayed haemolytic transfusion reaction develop?
5-10 days (IgG mediated - Duffy and Kidd)
56
What would a haemolysis screen show in delayed haemolytic transfusion reaction
↑ bilirubin ↑ LDH ↑ reticulocytes ↓ Hb DAT positive haemoglobinuria over few days Renal failure
57
What is the prognosis of transfusion-associated GVHD?
Always fatal
58
Which patients are most at risk of transfusion-associated GVHD?
Severely immunosuppressed
59
What is the cause of transfusion-associated GVHD?
pt immune system recognises donor lymphocytes as foreign → destroyed if susceptible pt (immcompromised) - lymphocytes not destroyed → lymphocytes recognise foreign HLA → attack pt liver, gut, skin and BM
60
How can transfusion-associated GVHD be prevented?
Irradiate blood for immunosuppressed patients HLA matched compoenents
61
What are the symptoms of transfusion-associated GVHD?
Severe diarrhoea Liver failure Skin desquamation Bone marrow failure DEATH
62
How long after a transfusion do post-transfusion purpura present?
7-10 days
63
Which patient group is affected by post transplantation purpura?
Human Platelet Antigen (HPA) 1a -ve patients previously immunised via pregnancy or transfusion (HPA-1a AB)
64
How should post-transfusion purpura be treated?
IV Ig usually resolves 1-4 weeks
65
What is the main complication risk of post-transfusion purpura?
Big bleeding
66
How can iron overload be prevented?
Chelation (Exjade)
67
Aetiology of HDN
ppl lacking RhD Ag can form Ab if exposed to the antigen via * blood transfusions * Pregnancy (foetal red cells enter mother's circulation during pregnancy or at delivery) first RhD-positive foetus - no issues but form anti-D Abs subsequent pregnancy + another RhD-positive foetus → Ig Abs cross placenta -\> destroy foetal red cells leading to severe anaemia ± HDN
68
When are pregnant women checked for RBC Immunoglobins during pregnancy, to prevent GVHD?
12 and 28w gestation (G+S)
69
If a pregnant woman has RBC antibodies that put the baby at risk of GVHD, what should be done?
1. Check if Father has antibodies (possibly inherited?) 2. Monitor Ig level (high/rising → more likely to affect foetus) 3. Check ffDNA sample - ID baby's Rh grp 4. Monitor foetus for anaemia 5. Deliver baby early
70
What is the anti-D dosing during pregnancy?
250IU (\<20w gestation) 500IU (\>20w gestation) larger doses for larger bleeds - FMH test (Kleihauer test) done if \>20w gestation and at delivery, to determine if more anti-D is needed than the standard dose if the foetal bleed is large
71
How does anti-D work during pregnancy to prevent GVHD?
RhD +ve foetal cells coated by exogenous anti-D immunoglobulin removed by mother's reticuloendothelial system (spleen) before they can sensitise mother to produce anti-D antibodies must be given within 72 hours of the sensitising event does NOT work if mother already sensitised and developed anti-D in the past
72
How quickly must anti-D be given following sensitisation events?
Within 72 hours
73
Recall some examples of sensitising events
give at delivery if baby RhD +ve Spontaneous miscarriages Amniocentesis/ CVS Abdominal trauma External cephalic version Still birth
74
What is the routine anti-D prophylaxis for mother's with no obvious sensitising events?
1500iu anti-D at 28-30w gestation (~1% of pregnancies have no obvious sensitising events yet RhD negative mothers become sensitised)
75
why do some patients have immune IgG Abs against RBC antigens?
previous transfusions pregnancy

Pathology ICSM COPY (90 decks)

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