Blood Transfusions

Question 1

What does the donor screening involve?

Answer 1

1. extensive questionnaire

2. multiple criteria for deferral

Question 2

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

Answer 2

HIV, HCV, HBV

Question 3

What are packed red blood cells (prbc)?

Answer 3

when one separates red cells from plasma and platelets

Question 4

How much prbc are in each unit?

Answer 4

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

Question 5

How long can one store blood?

Answer 5

42 days

Question 6

What is leukoreduced prbc?

Answer 6

when you remove leukocytes from rbcs

Question 7

What kinds of Ags are on a RBC surface?

Answer 7

1. proteins

2. complex carbs on lipids or proteins

Question 8

What is the basic O antigen made up off?

Answer 8

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

Question 9

What is the role of ABO glycosyltransferase?

Answer 9

attach a 6th sugar to the O antigen

Question 10

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

Answer 10

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

Question 11

Type A blood makes what Abs?

Answer 11

Abs to B Ag

Question 12

What subclass of Igs are the Abs against blood groups?

Answer 12

IgM

Question 13

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

Answer 13

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

Question 14

What blood groups can donate to O recipient?

Answer 14

O donors

Question 15

Who can donate to A blood types?

Answer 15

O and A

Question 16

Who can donate to B blood types?

Answer 16

O and B

Question 17

Who can donate to AB blood types?

Answer 17

All blood types

Question 18

What is antigenicity?

Answer 18

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

Question 19

What are the RBC Ags encoded by?

Answer 19

genes that show substantial allelic variation

Question 20

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

Answer 20

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

Question 21

What is the most common RhD?

Answer 21

a complete deletion of the coding sequence

Question 22

Why is RHD protein significant in obstetrics?

Answer 22

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

Question 23

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

Answer 23

give mother RhoGam – basically an immunization

Question 24

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

Answer 24

girls and women of childbearing age

Question 25

What are minor red cell Ags?

Answer 25

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

Question 26

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

Answer 26

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

Question 27

What are the steps of compatibility testing?

Answer 27

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

Question 28

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

Answer 28

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

Question 29

What is the objective of red cell transfusion?

Answer 29

to increase the patient's O2 carrying capacit

Question 30

What is measured for the O2 carrying capacity?

Answer 30

Hgb mainly but sometimes can look at Hct

Question 31

When should you give a red cell transfusion?

Answer 31

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

Question 32

When shouldn't you give a red cell transfusion?

Answer 32

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

Question 33

Is anemia a diagnosis?

Answer 33

no -- need to determine why patient has anemia

Question 34

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

Answer 34

if lab indications are questionable (such as Hgb > 8.0

Question 35

What is the average blood volume?

Answer 35

5 L

Question 36

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

Answer 36

500, 10% of blood volume

Question 37

What are some risks associated w/ red cell transfusion?

Answer 37

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

Question 38

How do hemolytic rxns present?

Answer 38

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

Question 39

What does the blood bank do for a transfusion rxn?

Answer 39

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

Question 40

What is the most common cause of immediate hemolytic rxns?

Answer 40

clerical error

Question 41

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

Answer 41

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

Question 42

Allergic rxns to plasma components?

Answer 42

urticaria (1-2%) and anaphylaxis rarely

Question 43

How to minimize allergic rxn?

Answer 43

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