Transfusion Flashcards
What is the minimum criteria required in healthy, volunteer donors?
Hb 135g/L men
Hb 125g/L women
Weight 50kg
What is checked to further improve the safety of the blood?
Donor health check
Contact details if becomes unwell post donation
What is involved in blood processing and testing?
Bag of whole blood centrifuged to separate into component parts
Samples undergo microbiological testing HIV, Hep B, Hep C, Hep E, HTLV, Syphilis
Red cells- stored at 4°C for 35 days
FFP (fresh frozen plasma) - stored -30°C for 3 years
Platelets- stored 22°C for 7 days with agitation
What are the products available from a blood donation?
Blood components
Red cells, FFP, platelets, cryoprecipitate
Blood products
Anti-D immunoglobulin, prothrombin complex concentrate
Blood products from pharmacy
Iv immunoglobulin, human albumin, specific Ig
How are blood groups influenced?
Membranes of red cells contains many different antigens.
The antigens that are expressed is determined by which blood group antigen genes we inherit from our parents.
38 different families of blood group systems have been identified.
What chromosome is the ABO gene located on?
Chromosome 9
What is phenotype vs genotype?
- Phenotype - which antigens are detected
- Genotype - which genes are present
What is Landsteiner’s law?
When an individual lacks 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
What blood type is the most compatible?
Blood group O
Donor blood O is compatible with recipient type O blood and groups A, B and Ab as well.
Donor group A is compatible with recipient group B. True/false?
False
Donor group A only compatible with recipient types A and AB.
Donor group B only compatible with recipient types B and AB.
Donor group AB is only compatible with recipient group AB. True/false?
True
What % of the population are RhD positive?
85%
What alleles are inherited for RhD?
2 alleles D and d, inherit one from each parent, can also be 2 alleles D and D.
d is silent so 2 alleles d and d genotype would cause RhD negative phenotype.
What can the anti-d antibody cause?
Can cause transfusion reactions and haemolytic disease of the foetus and new-born.
Avoid exposing RhD negative people to D antigen through transfusion. RhD negative blood should be given to RhD negative people.
What is the aim of pre-transfusion testing?
Identify ABO and RhD group of patient
Identify presence of clinically significant red cell antibodies
This allows for selection of appropriate blood for transfusion
What is antisera?
Using reagents with known antibody specificity to identify antigens present on red cell.
What are reagent red cells?
Using reagents with known antigen specificity to identify antibodies present on red cell.
What are the indirect and direct antiglobulin tests?
The direct and indirect Coombs tests, also known as antiglobulin test (AGT), are blood tests used in immunohematology.
The direct Coombs test detects antibodies that are stuck to the surface of the red blood cells.
The indirect Coombs test detects antibodies that are floating freely in the blood.
Stages of indirect antiglobulin test?
Reagent red cells expressing known antigen(s)
Add patient plasma
Add anti-human globulin
Look for agglutination
(Agglutination indicates the presence of an antibody)
What are the points to consider for selecting blood for 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, uses indirect anti-globulin (agglutination indicates donor cells are incompatible with patient plasma).
Agglutination = firmly stick or be stuck together to form a mass
Indications for 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 9in stable, non-bleeding patients).
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
Indication 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
When is monitoring required during transfusion?
Observation before blood is commenced
Observation at 15 minutes
Observations within 60 mins of completion
