3.10 Blood Transfusion Flashcards
What antigens will group A blood type patients have on their RBCs, and what antibodies in their plasma?
A antigens
Anti-B antibodies
What antigens will group B blood type patients have on their RBCs, and what antibodies in their plasma?
B antigens
Anti-A antibodies
What antigens will group AB blood type patients have on their RBCs, and what antibodies in their plasma?
A and B antigens
No antibodies
What antigens will group O blood type patients have on their RBCs, and what antibodies in their plasma?
No antigens
Anti-A and anti-B antibodies
Why can AB+ take blood from anyone?
AB people do not have any antibodies in their plasma, so there is nothing to attack the foreign RBCs when they are transfused
How do you cross match a sample of blood for transfusion?
Take a sample of the patient’s serum (contains antibodies) and the donor’s RBCs
If they agglutinate then the samples are incompatible
During blood testing, what infections are tested for?
HIV, HEP B C E, HTLV And Syphillis
Do we test for Creutzfeldt-Jacob Disease?
Yes
Who do we give red cells to?
Patients with anaemia
What RhD group are you if you lack the D antigen?
Negative
Do RhD negative patients have Anti-D antibodies in their plasma?
No, but they can make Anti-D antibodies
How do RhD Negative People make anti D antibodies?
RhD negative mother with an RhD positive baby
Transfusion of RhD positive blood
If a RhD negative patient has a blood transfusion with a RhD positive person, what implications does this have for their future transfusion?
Exposure to D antigen produces anti-D antibodies
Thus next transfusion must be with RhD negative blood to prevent haemolytic transfusion reaction
Haemolysis can cause anaemia, high bilirubin and jaundice
What is haemolytic disease of the newborn?
If a RhD negative mother has an RhD positive first child, anti-D antibodies are produced
If the second child is also RhD positive, anti-D antibodies cross the placenta and cause haemolysis of foetal red blood cells
What can haemolytic disease of the newborn cause?
If severe – hydrops fetails and death before birth
If less severe – high bilirubin thus brain damage, leading to death
Why can Anti-D antibodies cross the placenta?
They are class IgG
How can the formation of Anti-D antibodies in mothers be prevented?
Give them Anti-D Immunoglobins
How does giving the mother Anti-D immunoglobins work to prevent HDN?
Anti-D works by destroying any RhD positive blood in the mother’s circulation, before it can be recognized by the mothers systems and therefore before the mothers own Anti-D antibodies can be made, thus preventing HDN
Which blood component will patients need to replace all their clotting factors which have been depleted during massive bleeding?
Fresh frozen plasma
In an emergency which group of Fresh Frozen Plasma should we give when we do not know their blood group?
AB negative as the plasma will not contain any antibodies
In an emergency, which group of red cells can we give to any patients?
O Negative Blood - this is because O negative Red Cells do not have A or B antigens on the surface of the Red cells which could be attacked by the patients Anti-A Antibodies or Anti-B Antibodies
What gene controls blood group?
The ABO gene
How do genes code for ABO?
Adding a sugar residue to a common glycoprotein and fucose stem (H antigen) on the RBC membrane
What is added to the the common H antigen to make it an A antigen?
N-acetyl galactosamine
What is added to the the common H antigen to make it an B antigen?
Galactose
Which carbohydrate stem does group O have?
Only the H stem
Which ABO gene is recessive?
O
Which RhD group can be given to both positive and negative?
Negative
Which blood groups can RhD positive blood be given to?
Only RhD positive
What is group and screen?
Identify ABO antigens (forward group) and ABO antibodies (reverse group)
Find out RhD group
Perform antibody screen on plasma
How is antibody screening carried out?
Patient plasma is incubated with RBCs with all blood group antigens on them
If antibody screen is negative – any ABO and RhD compatible blood is given
If positive – identify antibody and give correct blood lacking antigen
Every donation is tested for what?
Infections, viruses, other clinically significant red cell antibodies
What is one unit of blood?
The whole blood or blood products derived from one single blood donation
What is the shelf life of red cells?
35 days
What is fresh frozen plasma used for?
Patients with prolonged PT and aPTT
Reversal of warfarin (vit K antagonist)
What is the shelf life of FFP and CRP?
3 years
What blood component should be given when there is a abnormal PT and aPTT?
FFP to replace all clotting factors
What is cryoprecipitate used for?
Replacing FVIII, FXIII, VWF and fibrinogen
Used in heavy bleeding
Why does cryoprecipitate not contain all the clotting factors?
Most degenerate at room temperature
Since cryoprecipitate has been thawed, it doesn’t contain these factors
Why is factor 8 and 9 heat treated for haemophilia treatment?
To inactivate viruses that may be present
When are patients given platelets?
Thrombocytopenia
Bone marrow failure
Massive bleeding
Disseminated intravascular coagulation (DIC)
When are patients given RBCs?
Anaemia
When are patients given factor 8 and 9?
Haemophilia A – factor 8
Haemophilia B – factor 9
When are patients given immunoglobulins?
To protect against hepatitis A
What two forms are platelets available in?
Pooled platelets or from a single donor
What class of antibodies are the ones found in plasma?
IgM
What condition can IgM antibodies cause?
Massive Intravascular Haemolysis
Due to risk of viral transmission, what are haemophilia patients now treated with?
Recombinant factor 8 and 9
What are the four stages of pre-transfusion testing that needs to be done?
ABO group
RhD group
Alloantibody screen
Cross matching
How many donors would be involved in 4 units of red cells?
4 donors
How many donors would be involved in 3 units of FFP?
3 donors
How many donors could be involved in 1 unit of platelets?
Either 4 donors pooled
or 1 donor with apheresis machine
What is the shelf life of platelets?
7 days
How many donors would be involved in 1 unit of cryoprecipitate?
5 for group pool
1 if apheresis machine used
