Haematology 13: Blood Transfusions 1 Flashcards
What happens in Haemolytic disease of the newborn ?
- RhD -ve mother has a RhD positive child and comes into contact with the blood during pregnancy/ or has a RhD +ve blood transfusion.
- The mother now makes anti-D
- The next baby is RhD +ve and this time the anti-D antibodies (IgG) cross the placenta
- This causes a delayed haemolytic reaction
Haemolytic disease of the newborn or severe foetal anaemia an heart failure (hydrops fetalis)
How does indirect antiglobulin technique work to screen blood ?
- Blood recipient’s plasma is put into test tube (contains recipient antibodies)
- Blood donor’s red cells are added to the test tube (has antigens)
- If the recipient has antibodies against the donor’s red cells they will form antigen-antibody complexes
- Coombs antibody is added (anti-human antibody)
- This causes cross linking if immune complexes are present
- if agglutination takes place the blood is not matched
What is the universal donor group for RBC ?
O- (no antigens on cells)
What is the universal donor group for plasma ?
AB (no antibodies in plasma)
Which method of blood transfusion is more acceptable for jehova’s witnesses ?
Cell salvage (collection, filtration and return of blood lost during surgery)
Why do patients with immunosuppression require irradiation of blood products ?
The donor lymphocytes can start reacting to self antigens and mount an immune response
This is known as transfusion associated graft versus host disease (TA-GvHD)
Which immune deficiency causes severe allergic reactions to donor blood plasma ?
IgA deficiency
Name 2 haematological diseases in which platelet transfusion is strongly contraindicated ?
HIT - heparin induced thrombocytopenia
TTP- thrombotic thrombocytopenic purpura
What is prothrombin complex concentrate (PPC) ?
A blood product containing vitamin K dependent clotting factors 10, 9, 7 and 2
what happens if you give ABO incompatible blood
intravascular haemolysis
what type of antibody are immune anti-D antibodies
IgG
do not cause direct agglutination of RBCs
not immediate haemolysis and death
delayed haemolytic transfusion reaction
what other Rh antigens are there
C, c, E, e, Kell (K), M, N, Duffy (Fy), Kidd (Jk)
Duffy and Kidd also cause delayed haemolytic transfusion reactions
what is given when there is an incompatibility between the mother and fetus in terms of Rh
give prophylactic anti-D immunoglobulin
what is reverse group testing
known A and B group RBCs are mixed with the patients plasma (IgM antibodies)
positive result = agglutination at the top
what are two types of crossmatching
full crossmatch - patients plasma combined with donor RBC at 37 degrees for 30-40 mins
immediate spin - incubate patients plasma and donor RBC for 5 mins and spin to detect ABO abnormalities (in emergencies)
what compatibility is needed for :
- RBC
- Platelets
- Plasma
RBC - ABO/D compatible
Plasma - ABO
Platelets - D
how are RBC stored
4 degrees 35 days
transfuse 1 unit over 2-3 hours
how are platelets stored
22 degrees 7 days
transfuse 1 unit over 20-30 mins
how is plasma stored
frozen up to 1 yr
transfuse 1 unit over 20-30 mins
list 3 indications for blood transfusion
major blood loss, >30% blood volume lost
peri-op critical care Hb <70g/L
post chemo Hb <80
I RBC should cause a 10g/L increase in Hb in a 70-80kg patient
what 3 ways can your own blood be transfused
peri-operative autologous deposit - not done in UK
intra-operative cell salvage - blood collected, centrifuged, filtered, washed, re-infused
post-op cell salvage - filtered and re-infused
what are 2 special transfusion requirements
CMV negative blood - intra-uterine and neonatal transfusions
Irradiated - highly immunocompromised (Ta- GvHD)
what 2 drugs can cause platelet dysfunction
aspirin
clopidogrel
3 indications for FFP
massive transfusion - blood loss > 150ml/min
DIC - with bleeding
liver disease + risk - PT ratio >1.5x normal
what is the treatment of choice to reverse warfarin
PCC
prothrombin complex concentrate
contains factors 2,7,9,10
