W16 - Blood transfusion 1 Flashcards
There are 2 systems/groups we use for determining blood group - what are they?
ABO system
Rh system
Give ABO incompatible blood transfusion, what happens?
massive INTRAVASCULAR haemolysis (fatal)
ABO groups are determined by … (2)
- antigens (sugars) on RBCs
- naturally-occurring IgM abs in the plasma
What abs does each blood group have?
Group A
Group B
Group AB
Group O
Group A = anti-B
Group B = anti-A
Group AB = none
Group O = anti-A, anti-B
What antigens does each blood group have?
Group A
Group B
Group AB
Group O
Group A = A antigen
Group B = B antigen
Group AB = A antigen, B antigen
Group O = none
Rh D antigens - what % of population is Rh D + and -?
RhD + = 85%
RhD - = 15%
RhD + individual - what blood can they receive?
RhD + RBCs
AND
RhD - RBCs (waste of resource though)
RhD - individuals - what blood can they receive?
RhD - RBCs
What happens if RhD - individual is given RhD+ blood for the first time?
make immune anti-D IgG antibodies if exposed to RhD + blood
Immune antibody class are anti-D antibodies? can they cross the placenta?
IgG - yes!
What sort of reaction do anti-D antibodies cause?
relayed haemolytic transfusion reaction
(do not cause direct agglutination of RBCs)
Rh D negative women exposed to Rh D positive blood can produce _____, which can cause disorder 1 or disorder 2 in pregnancy. Name these 2.
anti-D
- haemolytic disease of the newborn
- severe foetal anaemia and heart failure (hydrops fetalis)
The blood group is done before every transfusion - T or F
True
Describe forward group in blood group testing?
Forward group is the use of known anti-A and anti-B and anti-D reagents against patient’s RBCs
Describe reverse group in blood group testing?
Reverse group is the use of known A and B group RBCs (antigens) against patient’s plasma, checking for IgM specific abs
After doing forward and reserve group testing in blood testing, what else is checked? What happens in such mismatch?
Antibody screen => check for immune antibodies which are IgG, that form following exposure to RBC antigens different to those expressed by patient. A mismatch could result in delayed haemolytic transfusion reaction
Group & Save Antibody Screen => how is it checked?
2 or 3 reagent Group O red cells that have all other important antigens => incubate using INDIRECT ANTIGLOBULIN TECHNIQUE => red cell coated with IgG will bridge when Antiglobulin reagent added= visible clumps!
What happens if in blood group testing, the antibody screen comes back negative?
10-cell panel testing to identify specific RBC antibodies (essentially phenotyping)
In terms of Kell blood group - what do we give to certain groups of people? why?
Kell negative (K - ) blood to women of childbearing potential because anti-K can cause haemolytic disease of the newborn (HDFN).
For blood transfusion, a valid consent is required. What does this involve?
verbal AND written
* if transfused in surgery, must inform afterwards
3 pillars of patient blood management - what’s pillar 1?
1st pillar = optimise haematopoiesis:
optimal iron, B12, folate, erythropoietin
3 pillars of patient blood management - what’s pillar 2?
2nd pillar = minimise blood loss & bleeding:
stop anticoagulation + antiplatelet agents
3 pillars of patient blood management - what’s pillar 3?
3rd pillar = harness & optimise physiological tolerance of anaemia = optimise cardiac output:
- restrictive threshold for transfusion (Hb 70g/L)
What is the restrictive transfusion threshold?
Hb 70g/L
