Blood Transfusions Flashcards Preview

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Flashcards in Blood Transfusions Deck (43):
1

What does the donor screening involve?

1. extensive questionnaire
2. multiple criteria for deferral

2

What are the 3 main serum tests for infectious agents when donating blood?

HIV, HCV, HBV

3

What are packed red blood cells (prbc)?

when one separates red cells from plasma and platelets

4

How much prbc are in each unit?

250ml, 1 unit will increase Hgb 1g/dL

5

How long can one store blood?

42 days

6

What is leukoreduced prbc?

when you remove leukocytes from rbcs

7

What kinds of Ags are on a RBC surface?

1. proteins
2. complex carbs on lipids or proteins

8

What is the basic O antigen made up off?

Spingosine connected to 5 sugars (GalNac, Gal,GalNac, Glu, Fucose)

9

What is the role of ABO glycosyltransferase?

attach a 6th sugar to the O antigen

10

Which blood groups have the enzyme and what does it do for the blood group?

1. A alleles - adds GalNac to O Ag
2. B alleles - adds Gal to O Ag
3. O alleles - enzymes is inactive

11

Type A blood makes what Abs?

Abs to B Ag

12

What subclass of Igs are the Abs against blood groups?

IgM

13

What can happen is a recipient is transfused with ABO-incompatible red cells?

- lyse them all very quickly
- acute hemolytic transfusion rxns
- can be fatal

14

What blood groups can donate to O recipient?

O donors

15

Who can donate to A blood types?

O and A

16

Who can donate to B blood types?

O and B

17

Who can donate to AB blood types?

All blood types

18

What is antigenicity?

a measure of how likely it is that a potential Ab binding site wil actually induce an Ab response

19

What are the RBC Ags encoded by?

genes that show substantial allelic variation

20

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

RhD -- over 80% of D- individuals transfused with D+ red cells develop Abs

21

What is the most common RhD?

a complete deletion of the coding sequence

22

Why is RHD protein significant in obstetrics?

- RhD (-) mother having a RhD (+) baby can cause complications for future pregnancies because mother makes Rh-Ab that can cross the placenta.

23

How do you treat the problem with RhD-Abs in pregnancy?

give mother RhoGam -- basically an immunization

24

Who do you never give D+ red cells if they are D-?

girls and women of childbearing age

25

What are minor red cell Ags?

currently over 350 known Ag-Ab combinations exist due to minor red cell Ags (i.e. RhCE)

26

What should the blood bank do for minor red cell Ags?

screen recipients for ANY Abs to these Ags before any transfusion and identify

27

What are the steps of compatibility testing?

1. provide current blood speciment for a type and screen
2. Crossmatch is performed - mix donor cells w/ patient plasma and look for agglutination
3. if Ab screen is negative give blood
4. in emergency use O negative blood

28

When should one give blood speicmen to blood bank for surgery?

at least day before surgery but no more than 3 days before the surgery

29

What is the objective of red cell transfusion?

to increase the patient's O2 carrying capacit

30

What is measured for the O2 carrying capacity?

Hgb mainly but sometimes can look at Hct

31

When should you give a red cell transfusion?

1. when patient is symptomatic and anemic (increased HR, RR, confusion, weakness, dizziness)
2. Acute blood loss, rapid volume expansion
3. During or following an MI
4. Hgb trendline

32

When shouldn't you give a red cell transfusion?

1. patient is old and frail
2. asympotmatic coronary artery disease
3. expand blood volume
4. promote wound healing

33

Is anemia a diagnosis?

no -- need to determine why patient has anemia

34

When will you need to give a rationale for transfusion at the VA?

if lab indications are questionable (such as Hgb > 8.0

35

What is the average blood volume?

5 L

36

How much are 2 units of prbc in terms of cc?

500, 10% of blood volume

37

What are some risks associated w/ red cell transfusion?

1. CMV seroconversion
2. Fever w/out hemolysis
3. Anti-RBC Ab development
4. Urticaria
5. circulatory overload

38

How do hemolytic rxns present?

fever, chills, chest pain, hypotension
- overall nonspecific so if you see this after a transfusion, stop transfusion and ask blood bank to do work up for a transfusion rxn

39

What does the blood bank do for a transfusion rxn?

1. clerical check
2. look at serum (pink = acute hemolysis, yellow= icteric, subabcute/chronic hemolysis)
3. recheck ABO of patient and donor
4. repeat crossmatch
5. repeat Ab screen
6. preform a DAT

40

What is the most common cause of immediate hemolytic rxns?

clerical error

41

What is the common cause of delayed hemolytic rxns? How to minimize risk for future?

1. du to Ab to minor red cell ag
educate patient about Abti-RBC ab so it doesn't happen in future

42

Allergic rxns to plasma components?

urticaria (1-2%) and anaphylaxis rarely

43

How to minimize allergic rxn?

-premedicate w/ antihistamines for subsequent transfusion, or request washed red cells for any subsequent transfusions