Transfusion Medicine Flashcards
What is the purpose of trasfusing RBCs?
To increase O2 carrying capacity.
The most antigenic protein on the RBC surface is:
D antigen
a unit of packed RBCs (pRBCs), 250 ml, will increase Hb by ___ g/dL/
~1 g/dL
How long can you store pRBCs?
42 days
When is fresh frozen plasma (FFP) indicated?
Usually to replace clotting factors
1 unit of plasma, 200-250 ml, will increase clotting factors by ___%?
~20%
FFP must be stored at this temp.
-20 C
Does FFP have to be ABO compatible? Why or why not?
Yes, all the donor’s Abs are present!
What are the cryoprecipitates and what is their use? Do they need to be ABO compatible?
Cryoprecipitate is a source of fibrinogen, factors VIII, XIII, vWF. 15 mL (1 unit) of cryoprecip. will raise fibrinogen levels by 5-10 mg/dL.
Does not have to be ABO compatible. Although they do express ABO antigens, this just results in a shorter life, but does not impair their utility for treating an acute bleeding episode.
When is a platelet transfusion indicated?
To stop bleeding when a pt has a low platelet count (thrombocytopenia)
Rarely, to prevent bleeding when pt is thrombocytopenic
1 unit of platelets (300 mL) will increase platelet count by ~ ____K/uL (normal count is 150-450 K/uL).
~25K/uL
Can you refrigerate platelets?
Must they be ABO compatible?
No. Room temp storage life is only 4-5 days.
Does not need to be ABO compatible, no plasma/RBCs present.
What is the “O” antigen of RBCs?
The basic structural core of complex carbohydrates present on ALL RBCs. Everyone has the O antigen!
What is responsible for the variable blood types among humans?
Your genome encodes an enzyme, called ABO glycosyltransferase, which can attach a sixth sugar to the O antigen. Multiple alleles (variants) of the gene for this enzyme in the human gene pool. Fall into 3 classes, each transfers a different combination of A, A&B, B, or just O.
What is the genetic combination of alleles that yields an A, B, AB, or O blood type?
2 O alleles = type O 2 A alleles = type A 2 B alleles = type B 1 O + 1 A = type A 1 O + 1 B = type B 1 A + 1 B = type AB
What happens if a recipient is transfused with ABO-incompatible red cells?
They have Abs (IgM) to the antigens on the donor RBC surface.
Abs will fix complement > MAC complex > lysis
This is called an acute hemolytic transfusion reaction.
Can be fatal.
What is the most antigenic protein on the red cell surface?
RhD
Under what circumstances are pts determined to be RhD negative or D negative?
They have 2 deleted RhD alleles
What is the most common RhD type? Pos/Neg
RhD neg
Immunization of the mother during pregnancy to her fetus’s RhD can be prevented with:
administration of anti-Rh-gamma globulin
Which RBC surface protein is the only antigen that we routinely characterize in both donor and potential recipients?
RhD
Over 80% of D (-) individuals transfused with D (+) red cells develop Abs
What demographic NEVER is transfused with RhD positive blood if they are negative?
young girls and women of childbearing age
Let’s say that your pt has an inherent lack of IgA, and receives a whole blood transfusion. What is a possible complication of them receiving another transfusion in the future?
If transfused after developing an Ab to IgA, they can have a severe, life threatening allergic reaction.
What is a complication associated with multiple platelet transfusions?
Pts tend to become less responsive to platelet transfusions after 5-10 transfusions (i.e. their platelet counts stop going up much post transfusion).
Is giving pRBCs indicated in an effort to expand blood volume?
No
Does giving pRBCs promote wound healing?
No
Is administering pRBCs indicated during or immediately after an acute MI? Why or why not?
Yes. Increased mortality at Hb < 10. Admin of pRBCs elevated Hb (O2 carrying capacity)
What is an indication for plasma transfusion?
1) Replacing missing plasma proteins such as Factor VIII, or IX (hemophilias A & B), antithrombin III (rare pro-thrombotic condition), AdamTS13 deficiency (TTP)
Also, replacing multiple missing plasma proteins:
- Coumadin toxicity with bleeding
What are 3 indications for platelet transfusion?
1) Treat ongoing hemorrhage in a thrombocytopenic pt (platelet count < 50K/uL)
2) Prevent hemorrhage in pts with severe thrombocytopenia (platelet cound <10K/uL)
3) Treat or prevent hemorrhage in pt with dysfunctional platelets (qualitative, not quantitative defect due to platelet inhibitory drugs and pts who have undergone cardiopulmonary bypass {more drugs})
Name a few risks inherent to RBC transfusions.
Recipient immune response
Graft vs host disease
Volume overload
Transfusion transmitted infection
List some pathological effects of an immune response to transfusion.
Acute hemolytic reaction
Production of an Ab to a minor red cell antigen
Urticarial reaction (hives) to transfused plasma
Febrile reaction to transfused leukocytes
Why are sickle cell pts more at risk for an adverse event when transfused with RBCs?
~30% form Abs. Extended crossmatch should be standard of care. Includes:
ABO, Rh, RhCE, K compatibility
What is a particular risk to immunocompromized pts receiving RBC transfusion?
Graft vs host disease. Always use leukoreduced or irradiated red cells for immunocompromized pts
