Blood Groups and Transfusion Flashcards
(71 cards)
1
Q
ABO in blood are
A
red cell antigens
2
Q
what chromosome determines the red cell antigens?
A
chromosome 9
3
Q
what do the gene codes for A and B allow for?
A
code for transferases which modify
precursor called ‘H substance’ on red cell membrane
4
Q
how are ABO genes inherited?
A
1 from each parent
5
Q
what is the inheritance pattern of A, B and O genes?
A
A and B are dominant over O
A and B are co-dominant
O is silent
6
Q
what is landsteiners law?
A
When an individual lacks the A or B antigen the
corresponding antibody is produced in their plasma
Naturally occurring antibodies cause haemolysis of red cells expressing the specific antigen = via gut bacteria similar in structure to A and B antigen,
7
Q
people with blood group O have genotype…
A
OO
8
Q
people with blood group A have genotype…
A
AA or AO
9
Q
people with blood group B have genotype…
A
BB or BO
10
Q
people with blood group AB have genotype…
A
AB
11
Q
people with blood group A have which antigen on red cells?
A
A
12
Q
people with blood group B have which antigen on red cells?
A
B
13
Q
people with blood group AB have which antigen on red cells?
A
A and B
14
Q
people with blood group O have which antigen on red cells?
A
Neither
15
Q
people with blood group A have which antibody in the plasma?
A
anti-B
16
Q
people with blood group B have which antibody in the plasma?
A
anti-A
17
Q
people with blood group AB have which antibody in the plasma?
A
neither
18
Q
people with blood group O have which antibody in the plasma?
A
anti-A and anti-B
19
Q
people with blood group O can receive blood from which groups?
A
O only
20
Q
people with blood group A can receive blood from which groups?
A
A and O
21
Q
people with blood group B can receive blood from which groups?
A
B and O
22
Q
people with blood group AB can receive blood from which groups?
A
A, B, O, AB
23
Q
what are the two main blood group systems?
A
ABO, Rh system
24
Q
what is the genotype of RhD+?
A
DD or Dd
25
what is the genotype of RhD-?
dd
26
what is the inheritance pattern of RhD?
* 2 alleles D and d, inherit one from each parent
* d is silent
* need dd to be negative
27
when does RhD system cause problems?
transfusion reactions and haemolytic disease of the fetus and newborn
28
how does RhD cause problems?
exposing RhD negative people to D antigen (RhD+)
29
what is the minimum criteria for blood donation?
– Hb 135g/L men
– Hb 125g/L women
– Weight 50kg
30
what microbiological testing do blood donations go through?
HIV, Hep B, Hep C, Hep E, HTLV, Syphilis
31
how long are red cells stored for?
4°C for 35 days
32
how long is FFP stored for?
-30°C for 3 years
33
how long are platelets stored for?
22°C for 7 days with agitation
34
what blood components are available via donation?
– Red cells, FFP, platelets, cryoprecipitate
35
what blood products are available via donation?
– Anti-D immunoglobulin, prothrombin complex concentrate
36
what blood products are available via pharmacy?
– Iv immunoglobulin, human albumin, specific Ig
37
what is vital in pre-transfusion testing?
1. Identify ABO and RhD group of patient
| 2. Identify presence of clinically significant red cell antibodies
38
what two tests are used for ABO grouping?
Direct Coombs
| Indirect Coombs
39
what is direct coombs test?
Use reagents with known antibody specificity to identify antigens present on red cell
40
what is indirect coombs test?
Use red cells with known antigen specificity to identify antibodies present in plasma
41
what is the summary of the reaction of a direct coombs test?
antigen on red cells + antibody specific for antigen of interest = agglutination of red cells
42
what is the summary of the reaction in a indirect coombs test?
Red Cells + Antibody + Sensitisation + AHG = agglutination (indicates presence of antibody)
43
what is the process of a direct coombs test?
– Test patient’s red cells with anti-A, anti-B and anti-D antisera
– identify antigens on the red cells
– IgM reagents- direct agglutination
44
what is the process of a indirect coombs test?
– Reagent red cells (group B to confirm anti B)
| – Addition of anti-human globulin (AHG) to plasma/ red cell suspension facilitates red cell agglutination
45
why is AHG added to plasma/red cell suspension?
– IgG only have 2 binding sites (won’t have agglutination) – add anti-globulin – if antibody has bound to red cell, anti-globulin binds and induces agglutination
46
what are the indications for red cell transfusion?
Symptomatic anaemia Hb<70g/L (80g/L if cardiac disease)
Major bleeding
Always consider cause before transfusion - alternative?
Transfuse a single unit of red cells and then reassess patient
47
what are the indications for platelet what are the indications for platelet transfusion??
* 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
* Always consider the cause before transfusion
48
what are the indications for FFP transfusion?
* Treatment of bleeding in patient with coagulopathy (PT ratio >1.5)
* Prophylaxis prior to surgery or procedure in patient with coagulopathy (PT ratio >1.5)
* Management of massive haemorrhage
* Transfuse early in trauma
* Not in absence of bleeding/ planned procedure
49
what are the 9 steps in blood transfusion?
1. Request
2. Sample
3. Sample Receipt
4. Testing
5. Component Selection
6. Labelling
7. Collection
8. Prescription
9. Administration
50
when is the patient observed during blood transfusion?
* Observations before blood is commenced
* Observations at 15 minutes
* Observations within 60 minutes of completion
51
what are the different types of transfusion reactions?
Acute Transfusion Reactions (ATR)
Acute Haemolytic Transfusion Reaction (AHTR)
Transfusion Associated Circulatory Overload
Mild Reaction
Delayed Haemolytic Transfusion Reactions
TRALI (transfusion associated lung injury)
52
when do acute transfusion reactions occur?
early
53
what are the symptoms of ATR?
chills, rigors, rash, flushing, feeling of impending doom, collapse, loin pain, resp distress
54
what are the signs of ATR?
fever, tachycardia, hypotension, tachycardia
55
what is initial management in all transfusion reactions?
1. Stop the transfusion
2. Assess the patient urgently ABCDE approach
– BP, pulse, temp, oxygen sats, clinical examination
3. Re-check compatibility tag against patient details and inspect pack for evidence of contamination
4. Document event in medical notes
56
what evidence could point to a severe or life threatening reaction?
* Evidence of life threatening airway/ breathing or circulatory problem
* Evidence of wrong component transfused/ bacterial contamination
57
what is the management of bacterial contamination of blood component
* Culture patient and remains of unit
* Treat supportively and with broad spectrum antimicrobials
* Need to inform transfusion lab so other units can be quarantined
58
what the mechanism of AHTR?
ABO incompatibility
59
what is the pathophysiology of AHTR?
Binding of IgM anti-A or –B antibodies to their corresponding antigen leads to complement activation and lysis of transfused cells
Release of inflammatory cytokines
intravascular coagulation, renal failure
60
what are the consequences of AHTR?
Shock, increased vascular permeability, disseminated intravascular coagulation, renal failure, Often fatal
61
what is the transfusion lab management of AHTR?
o Repeat ABO and RhD group of pre and post transfusion samples - Is there a discrepancy?
o Direct antiglobulin test - Is there antibody bound to donor cells?
o Repeat crossmatch - Are the donor unit(s) incompatible?
o Send remains of unit for culture
62
what are the clinical features of Transfusion Associated Circulatory Overload?
– Respiratory distress within 6 hours of transfusion
– Raised blood pressure
– Raised JVP
– Positive fluid balance
63
what are the risk factors for Transfusion Associated Circulatory Overload?
– Elderly patients, cardiac failure, low albumin, renal impairment, fluid overload
64
what is the management of Transfusion Associated Circulatory Overload?
– Oxygen and supportive care as required
– Diuretics - furosemide
– Consider slowing rate of further transfusions
– Consider diuretics with future transfusion
– Only transfuse minimum volume required
– Aim to identify patients at risk before first transfusion
65
what are the causes of mild transfusion reactions?
– Febrile non-haemolytic transfusion reaction
| – Mild allergic reaction
66
what are the clinical features of mild transfusion reactions?
•Isolated temp rise >38 and rise of 1-2 degrees or rash only
67
what is the management of mild transfusion reactions?
– Continue transfusion- consider slowing rate
– Close monitoring of patient in case condition worsens
– Consider paracetamol/ anti-histamine
68
when does Delayed Haemolytic Transfusion Reactions occur?
Extravascular haemolysis 5-10 days post transfusion
69
what is the pathophysiology of Delayed Haemolytic Transfusion Reactions?
Patient mounts delayed immune response to red cell antigen- usually IgG
o Positive DAT
70
what are the features of Delayed Haemolytic Transfusion Reactions seen in blood tests?
o Hb may drop, raised bili, LDH
| o Positive DAT and detection of alloantibody
71
what is the Resuscitation of Severe Allergic Transfusion Reaction?
```
Lie patient
Administer adrenaline
Administer chlorpheniramine
Administer salbutamol
Administer corticosteroids
```
