Transfusion Medicine

Question 1

What is the purpose of trasfusing RBCs?

Answer 1

To increase O2 carrying capacity.

Question 2

The most antigenic protein on the RBC surface is:

Answer 2

D antigen

Question 3

a unit of packed RBCs (pRBCs), 250 ml, will increase Hb by ___ g/dL/

Answer 3

~1 g/dL

Question 4

How long can you store pRBCs?

Answer 4

42 days

Question 5

When is fresh frozen plasma (FFP) indicated?

Answer 5

Usually to replace clotting factors

Question 6

1 unit of plasma, 200-250 ml, will increase clotting factors by ___%?

Answer 6

~20%

Question 7

FFP must be stored at this temp.

Answer 7

-20 C

Question 8

Does FFP have to be ABO compatible? Why or why not?

Answer 8

Yes, all the donor’s Abs are present!

Question 9

What are the cryoprecipitates and what is their use? Do they need to be ABO compatible?

Answer 9

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.

Question 10

When is a platelet transfusion indicated?

Answer 10

To stop bleeding when a pt has a low platelet count (thrombocytopenia)
Rarely, to prevent bleeding when pt is thrombocytopenic

Question 11

1 unit of platelets (300 mL) will increase platelet count by ~ ____K/uL (normal count is 150-450 K/uL).

Answer 11

~25K/uL

Question 12

Can you refrigerate platelets?

Must they be ABO compatible?

Answer 12

No. Room temp storage life is only 4-5 days.

Does not need to be ABO compatible, no plasma/RBCs present.

Question 13

What is the “O” antigen of RBCs?

Answer 13

The basic structural core of complex carbohydrates present on ALL RBCs. Everyone has the O antigen!

Question 14

What is responsible for the variable blood types among humans?

Answer 14

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.

Question 15

What is the genetic combination of alleles that yields an A, B, AB, or O blood type?

Answer 15

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

Question 16

What happens if a recipient is transfused with ABO-incompatible red cells?

Answer 16

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.

Question 17

What is the most antigenic protein on the red cell surface?

Answer 17

RhD

Question 18

Under what circumstances are pts determined to be RhD negative or D negative?

Answer 18

They have 2 deleted RhD alleles

Question 19

What is the most common RhD type? Pos/Neg

Answer 19

RhD neg

Question 20

Immunization of the mother during pregnancy to her fetus’s RhD can be prevented with:

Answer 20

administration of anti-Rh-gamma globulin

Question 21

Which RBC surface protein is the only antigen that we routinely characterize in both donor and potential recipients?

Answer 21

RhD

Over 80% of D (-) individuals transfused with D (+) red cells develop Abs

Question 22

What demographic NEVER is transfused with RhD positive blood if they are negative?

Answer 22

young girls and women of childbearing age

Question 23

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?

Answer 23

If transfused after developing an Ab to IgA, they can have a severe, life threatening allergic reaction.

Question 24

What is a complication associated with multiple platelet transfusions?

Answer 24

Pts tend to become less responsive to platelet transfusions after 5-10 transfusions (i.e. their platelet counts stop going up much post transfusion).

Question 25

Is giving pRBCs indicated in an effort to expand blood volume?

Answer 25

No

Question 26

Does giving pRBCs promote wound healing?

Answer 26

No

Question 27

Is administering pRBCs indicated during or immediately after an acute MI? Why or why not?

Answer 27

Yes. Increased mortality at Hb < 10. Admin of pRBCs elevated Hb (O2 carrying capacity)

Question 28

What is an indication for plasma transfusion?

Answer 28

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

Question 29

What are 3 indications for platelet transfusion?

Answer 29

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})

Question 30

Name a few risks inherent to RBC transfusions.

Answer 30

Recipient immune response
Graft vs host disease
Volume overload
Transfusion transmitted infection

Question 31

List some pathological effects of an immune response to transfusion.

Answer 31

Acute hemolytic reaction
Production of an Ab to a minor red cell antigen
Urticarial reaction (hives) to transfused plasma
Febrile reaction to transfused leukocytes

Question 32

Why are sickle cell pts more at risk for an adverse event when transfused with RBCs?

Answer 32

~30% form Abs. Extended crossmatch should be standard of care. Includes:
ABO, Rh, RhCE, K compatibility

Question 33

What is a particular risk to immunocompromized pts receiving RBC transfusion?

Answer 33

Graft vs host disease. Always use leukoreduced or irradiated red cells for immunocompromized pts