Blood Trandusions 2 Flashcards
Why is blood transfusion necessary?
Insufficient blood due to bleeding or failure of production
Includes excess rate of destruction.
What are the key components of blood transfusion?
Blood donors, blood components and products, blood groups
Focus on ABO and RhD.
What factors are considered when screening blood donors?
Health of donor, exposure to infectious agents, sexual history, travel, tattoos
Includes medication and other diseases.
What infectious agents are blood donors screened for?
Hepatitis B/C/E, HIV, syphilis, HTLV, sometimes malaria, West Nile virus, Zika virus, CMV
Screening is crucial for donor safety.
How are red blood cells typically prescribed for transfusion?
By unit, usually 450 mls from donor
This is about 10% of total blood volume.
What is the storage condition for red blood cells?
Stored at 4°C
Transfusion is done over 2-4 hours.
What are the indications for red cell transfusion?
Severe acute anemia, quality of life improvement, surgery preparation, reversing damage from red cells
Example: Sickle Cell Disease.
What is the typical dose for platelet transfusion?
1 dose platelets = 4 pooled or 1 apheresis donor
Increments are approximately 30.10^9/L.
What is the shelf life of platelets?
7 days
Stored at ~22°C and transfused over 20-30 minutes.
What are the indications for plasma transfusion?
Massive hemorrhage, DIC with bleeding, prophylactic for procedures, deranged coagulation
Example: Thrombotic thrombocytopenic purpura (TTP).
What do ABO blood group antigens encode?
Glycosyltransferase
A and B genes code for transferase enzymes.
What antibodies are produced based on blood group?
A produces anti-B, B produces anti-A, O produces anti-A and anti-B, AB produces no antibodies
Immune tolerance is key.
What is the significance of RhD blood group system?
DD, Dd, dd genotypes; anti-RhD can cause transfusion reactions
RhD negative individuals can make anti-D if exposed to RhD+ cells.
What is the purpose of the Coombs Test?
Detects antibodies against red blood cells
Used in autoimmune hemolytic anemia and transfusion reactions.
What is the difference between direct and indirect Coombs Test?
Direct tests for autoimmune reactions, indirect is for cross matching
Both help identify blood compatibility.
What happens during ‘Group and Screening’?
ABO and RhD type checked, antibodies screened in serum
Uses gel columns and automation.
What is Haemolytic Disease of the Newborn (HDN)?
Condition caused by maternal anti-D antibodies crossing the placenta
Can lead to anemia, jaundice, or death in utero.
How can HDN be prevented?
Using prophylactic anti-D
Routine administration at 28/40 weeks.
What are cellular therapies in the context of blood transfusion?
Leucapheresis, stem cells for transplantation, lymphocytes for immunotherapy
Includes CAR-T cells.
Fill in the blank: The ABO gene encodes _______.
glycosyltransferase
True or False: Blood group O individuals can receive blood from any other blood group.
False
O group individuals can only receive O group blood.
What is the purpose of cross matching?
To ensure compatibility between donor and recipient blood
Involves mixing patient plasma with donor red cells.
