Blood Groups and Blood Transfusion Flashcards
How much blood is collected from a donor?
Approximately 400 ml (anti-coagulated)
What is donated blood tested for?
ABO, Rh(D) blood groups, antibody screen
Infectious agents to prevent infections
HIV, Hep B+C, syphilis, HTLV-1
What happens to donor blood?
It is fractionated into its major components:
Packed RBCs
Fresh Frozen Plasma
Platelets
Cryopercipitate
Is it possible to get whole blood transfusions in Aus?
No
What is the haematocrit of packed red blood cells?
60 - 70%
How can clotting factors be transfused into another person?
Through fresh frozen plasma
What happens to plasma after fractionation?
Some of it is transported to melbourne (CSL) where it is further fractionated into individual proteins such as albumin, prothrombin x, and other important proteins.
What are the blood grouping systems that are used?
ABO
Rhesus
Other (not tested routinely)
How many blood groups do we have?
approximately 400 on RBC membrane
What is the H in ABO(H)?
precursor molecule for groups A and B
When do we produce antibodies to opposite blood group?
By 3 - 6 months of age
What type of antibodies are anti-A and anti-B antibodies?
IgM
What happens if antibodies interact with blood type?
Cause rapid severe intramuscular haemolysis and immediate transfusion reaction
What kind of disease does Group O mother cause to a group A baby?
Mild haemolytic disease
What are the frequencies of blood groups?
A: 39%
B: 11%
AB: 4%
O: 46%
How many Rh antigens are there?
40 (d does not exist and D is the one we use most often)
What is the frequency of Rh(D) positive and Rh(D) negative?
Positive 85%
Negative 15%
Is there a naturally occuring anti-D antibody?
Only after exposure to D antigen.
What is a condition that is problematic in Rh(D)?
Anti-D Ig given to Rh(D) negative mothers after birth of Rh(D) positive infant to prevent production of immune anti-D that causes haemolysis in subsequent pregnancies
What causes haemolytic disease of the newborn? What is allo-immune haemolytic anaemia?
Maternal IgG antibodies from maternal circulation to the foetus via the placenta. Foetal RBC destroyed by maternal antibodies.
Anti-D is made in 1st pregnancy by Rh(D) negative mother and then subsequent pregnancies result in anti Rh(D) antibodies.
What are some other major blood group systems?
Kell (K/k)
Duffy (Fy)
Kidd (jk)
Lewis (Le)
What percentage of people have Kell antigens?
10%
What does K antigen do?
it is immunogenic and can cause haemolysis
How does malaria invade RBC?
Through Duffy antigen
What is an antibody screen needed for?
To check if any unexpected antibodies are present in patient plasma including antibodies to other blood groups such as anti-E,K,Jka
What is crossmatching?
Final step before patient receives transfusion.
A fail-safe method of preventing incompatibilities between donor and recipient blood.
What is the most common blood component used?
Packed Red Blood Cells
What is the haematocrit in packed RBCs?
60 - 70%; stored as 250 - 300ml packets
How are packed RBCs stored?
2 - 6 degrees for up to 42 days.
What is done to leucocytes in packed RBCs?
They are removed through filtration system
What are packed RBCs used to increase?
Oxygen carrying capacity
Who is given packed RBCs?
Patients with haemorrhage
Symptomatic anaemia
Anaemia and urgent surgery
Bone marrow dysfunction or failure
How much does a bag of packed red blood cells increase haemoglobin?
10 g/L
Who is the universal donor of blood?
Group O Rh(D) Negative
How are platelets stored?
at 20 - 24 degrees for up to 5 days
Do platelets have AB antigens?
No
How many platelets are transferred per transfusion?
3 x 10^11 from whole blood
What is apheresis?
a technique by which a particular substance or component is removed from the blood, the main volume being returned to the body.
What blood group is a universal plasma donor?
AB
Who can donate fresh frozen plasma? What does it contain?
Males only, contains all plasma proteins
How is fresh frozen plasma stored?
-30 degrees for up to a year and thawed before use
How much fresh frozen plasma is there per bag and what is the dose used?
Bag = 200ml
Dose = 10 - 15 ml/kg
When should FFP be used?
Coagulopathic bleeding
Massive haemorrhage
Massive transfusion
When should platelets be used?
Thrombocytopenia and bleeding or surgery
Prophylaxis
When should packed RBCs be used?
Haemorrhage
Symptomatic anaemia
Anaemia and urgent surgery
Bone marrow dysfunction or failure
What is cryoprecipitate?
The white precipitate derived from FFP concentrated in clotting factores (particularly fibrinogen, factor VIII, and Von Willebrand Factor)
How much does a bag of cryoprecipitate contain?
30 - 40ml
How is cryoprecipitate stored?
Below -25 degrees
Is cryoprecipitate ABO testing necessary?
No but cryoprecipitate should be compatible with recipient RBCs
Is cryoprecipitate ABO testing necessary?
No but cryoprecipitate should be compatible with recipient RBCs
What concentrates are formed from blood products?
Albumin
Immunoglobulins
Factor concentrates
Testing reagents
What can go wrong early with transfusion?
Haemolytic transfusion reaction (ABO incompatibility)
Sepsis: Bacteria contaminated blood product
Transfusion related acute lung injury
Transfusion associated circulatory overload
Febrile non-haemolytic transfusion reaction
Urticarial (allergic) reactions
What can go wrong in 7 - 10 days after transfusion?
Delayed haemolytic transfusion reaction
What can go wrong later after transfusion?
Viral infections
Immune sensitisation
Iron overload
What causes delayed haemolytic reactions?
Patients form antibodies in response to a transfusion
How often do delayed haemolytic reactions occur?
1:5000 transfusions
What causes delayed haemolytic reactions?
Patients form antibodies in response to a transfusion.
Antibodies are made in response to prior RBC exposure. Exposure to the antigen with current transfusion generates an anamnestic antibody response.
What are the symptoms of delayed haemolytic reactions?
Unexplained anaemia, fever and jaundice
What causes transfusion related lung injury?
Neutrophils present in transfused blood product
What is the frequency of death in transfusion relatedacute lung injury?
1:5000 to 1:100000 (high mortality due to pulmonary oedema)
What causes febrile and allergic reactions?
Recipient antibodies react with donor white cells or proteins
How common are febrile reactions?
Low due to use of leucodepleted red cell units
How are febrile and allergic reactions managed?
Supportive management with antipyretics and antihistamines
What can potentially occur in febrile and allergic reactions due to blood transfusion?
Anaphylaxis in IgA deficient patients
