Transfusion Flashcards
What is the minimum criteria for Hb and weight to be allowed to donate blood?
- Hb 135g/L men
- Hb 125g/L women
- Weight 50 kg
Can a donor remain anonymous?
NO - they must always give contact details
Blood samples undergo testing for various different viruses including …
- HIV
- Hep B
- Hep C
- Hep E
- HTLV
- Syphilis
What happens during processing of a blood sample?
The bag of blood from the donor is spun to separate all components
How are red cells stored?
Red cells stored at 4°C for 35 days
How is FFP stored?
FFP stored 30°C for 3 years
How are platelets stored?
Platelets stored 22°C for 7 days with agitation
Blood components only come from one donor sample
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Blood products can come from many different donors
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Name the 4 different blood components.
- Red cells
- FFP
- Platelets
- Cryoprecipitate
Name the 2 different blood products.
- Anti-D immunoglobulin
* Prothrombin complex concentrate
Name the 3 different blood products from pharmacy.
- IV immunoglobulin
- Human albumin
- Specific Ig
What is an antigen?
Any substance which can trigger an immune response
In a RBC, where are antigens present?
On the membrane of a red cell there are many antigens
Where is the ABO gene located?
Chromosome 9
What do A and B genes code for?
‘A’ and ‘B’ genes code for transferases which modify precursor called ‘H substance’ on red cell membrane
What is the relationship between A, B and O?
A and B are co-dominant over O
What is the relationship between A and B?
A and B are co-dominant
O is ______
Silent
We get one gene (A, B or O) from each parent
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What is the most common ABO group?
O
What is the least common ABO group?
AB
What antigens are present on red cells of group O?
None
Phenotype is?
Which antigens are detected
Genotype is?
Which genes are present
Outline Landsteiner’s law.
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
Makes ABO the most clinically significant blood group system
These start to be formed from 6 months of life, because there is bacteria in the gut with similar appearance to A and B antigen
What antibody is present in group A?
Anti B
What antibody is present in group B?
Anti A
What antibody is present in group AB?
Neither A or B
What antibody is present in group O?
Anti A and Anti B
Who can O be transferred to?
Anyone
What blood can AB people get?
Any
What % of the population are RhD+?
85%
What are the 2 forms of RhD which you can inherit from each parent?
- d
* D
RhD + genotype?
DD or Dd
RhD - genotype?
dd
If someone is RhD + it means that a D antigen is found on the surface of their red blood cells
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Anti-D antibody can cause transfusion reactions and haemolytic disease of the foetus and newborn
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RhD negative blood to RhD negative people
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Individuals can be sensitised by exposure to foreign antigens via many events …
- Pregnancy
* Transfusion
What may repeated exposure to foreign antigens result in?
Transfusion reaction
Outline the aims of pre-transfusion testing.
- Identify ABO and RhD group of patient
- Identify presence of clinically significant red cell antibodies
Allow selection of appropriate blood for transfusion
When doing ABO grouping, what kind of reagents should be used?
Use reagents with known antibody specificity to identify antigens present on red cell
When doing ABO grouping, what kind of red cells should be used?
Use red cells with known antigen specificity to identify antibodies present in plasma
What is agglutination of red cells?
Red cells come together and stick in a clump
What does agglutination indicate?
The presence of an antibody
When doing ABO/D grouping, what should you test the patients red cells with?
Test patient’s red cells with anti-A, anti-B and anti-D antisera
In ABO/D grouping, what agents are used to see agglutination?
IgM reagents
When doing ABO/D grouping, what are you looking for?
To identify antigens on the red cell surface membrane
How do you identify antibodies in plasma during an ABO/D grouping?
Test patient’s plasma against reagent red cells of group A and group B
How do you identify antigens on red cells during an ABO/D grouping?
- Identify antigens on the red cells
* IgM reagents- direct agglutination
Addition of anti-human globulin (AHG) to plasma/ red cell suspension facilitates red cell agglutination
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How is antibody screening done?
Test patient’s plasma against several reagent red cells which express a known range of antigens
- Identify antibodies in the plasma
- Use the indirect anti-globulin test
What 3 things should be considered when making a selection for blood for a transfusion?
- Matched for, or compatible with, patient’s ABO and RhD group
- Consider presence of red cell antibodies
- Perform crossmatch to check donor cells are compatible with patient plasma
Outline the indications for a red cell transfusion.
- Symptomatic anaemia Hb<70g/L (80g/L if cardiac disease)
- Major bleeding
- Always consider cause before transfusion – Is there an alternative?
- Transfuse a single unit of red cells and then reassess patient
Outline the indications for a 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
1 unit of platelets is starting dose and usually all that is needed
Outline the indications for an 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
When is FFP transfusion NOT done?
Not in absence of bleeding/planned procedure
Patient identification at every step is extremely important
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What test tube are the blood sample in?
Pink
What should the label of every blood test tube include?
- Name, ward, gender
- DOB, date and time of sampling, CHI number
- Signature
How is a patient monitored during a transfusion?
- Observations before blood is commenced
- Observations at 15 minutes
- Observations within 60 minutes of completion
Discuss acute transfusion reactions and other adverse reactions during lab practical
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If patient says they feel unwell or observations change then transfusion must be stopped and re-evaluated
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