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Year 2 Collin > Haem 11 - Blood transfusion > Flashcards

Haem 11 - Blood transfusion Flashcards

1
Q

When do we use blood

A

Balance between benefits and risks - i.e. when no safer alternative available e.g. if massive bleeding and “plain fluids” not work, if anaemic and B12/Iron/folate insufficient

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2
Q

Describe the basis of the ABO blood groups

A

All blood has a common H antigen stem.

If A group: A antigen attached onto common H stem

If B group: B antigen attached onto common H stem

If AB: Some stems with A on, some stems with B on

If O group: nothing else added on, just plain H stem

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3
Q

Describe the genes for ABO blood group

A

A gene - codes for enzyme which adds n-acetyl galactosamine to common H stem (common H stem = glycoprotein and glucose stem)

B gene - codes for enzyme which adds galactose to common H stem

A and B are codominant, O gene is recessive

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4
Q

Everyone has antibodies against any antigen NOT present on own RBC. e.g. I am group B, so I have anti-A antibodies. Which immunoglobulin can cause damage

A

IgM.

I have IGM-antiA so if I am given group A blood - this would trigger the complement cascade and cause haemolytic of my RBC - can be fatal

NB - in labs IgM antibodies react with their corresponding antigen (e.g. IgM anti-A will react with group A antigens and cause agglutinatination)

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5
Q

Group O = universal donor. What is the universal recipient?

A

Group AB

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6
Q

What is crossmatching

A

Add patients plasma against RBC we are going to transfuse - check to ensure no agglutination

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7
Q

Describe RH groups (specifically RhD)

A

There is RhD positive and RhD negative.

Genes for RhD groups:

  1. D = codes for D antigen on RBC membrane
  2. d = codes for no antigen, is recessive

So patient must be homozygous (dd) to be RhD negative.

DD/Dd = RhD positive

85% people positive

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8
Q

Anti-D antibodies are what type of antibodies?

A

IgG

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9
Q

ABO, pretty much form antibodies straight after birth. With RhD, you can still make anti-D antibody if you are sensitised. How is one sensitised

A
  1. Transfusion
  2. If they’re pregnant with an RhD positive foetus

RhD positive - D antigen present, no anti-D antibody

RhD negative - no D antigen present, can make anti-D if sensitised

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10
Q

Which is the only type of antibody that can cross the placenta?

A

IgG

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11
Q

What are the implications for a patient if they have anti-D antibodies?

A
  1. All future transfusions must be done with RhD negative blood - or else the anti-D would react with RhD positive blood causing delayed haemolytic transfusion reaction - anaemia, high bilirubin, jaundice, etc)
  2. Haemolytic disease of the newborn (HDN). If mother (RhD neg) has anti-D antibodies - but foetus has RhD positive blood - mothers IgG anti-D can cross placenta —> cause haemolytic of foetal red cells - can be fatal if severe
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12
Q

Transfuse blood of same RhD group.

A

Y

no harm giving RhD negative to a RhD positive patient - just wasteful

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13
Q

In case of immediate emergency - which blood group is given

A

O negative

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14
Q

There are other red cell antigen groups. How many?

A

About 12 - but not all cause clinically significant effects (e.g. haemolysis)

About 8% patients transfused develop antibodies to some antigens - in FUTURE you must use corresponding antigen negative blood - otherwise you risk delayed haemolytic reaction

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15
Q

Before each transfusion episode, what are the checks done

A
  1. Test ABO and RhD group

2. Do an “antibody screen” of their plasma

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16
Q

1 unit of blood is collected into bad with anticoagulant. We don’t routinely give whole blood to patients - we use the parts needed. Explain

A
  1. More efficient - less waste - patients don’t need all the “components”
  2. Some components quickly degenerate if stored as “whole blood”
  3. RBC concentrated as plasma removed -also avoids fluid overloading patients

Blood split up by centrifugation - RBC bottom, platelets middle, plasma top.

17
Q

What are the different forms of plasma

A
  1. Fresh frozen plasma
  2. Cryoprecipitate (Fibrinogen / F1/8)
  3. Plasma for fractionation (e.g. albumin, F8/9, Igs, anti-D, etc)
18
Q

How long is an RBC donation kept for

A

5 weeks - stored at 4 degrees

Donations given via blood giving set - filters to remove clumps/debris

19
Q

Describe preservation and storage of fresh frozen plasma (FFP)

A
  1. Stored at -30
  2. 2 years shelf life
  3. Dose = 12-15ml/kg
  4. Must thaw approx 20-30 mins before use (too hot = proteins cook)

MUST MATCH - but not deadly, just anaemia + pain if you don’t match as some antibodies still present

20
Q

Which coagulation factors does warfarin inhibit

A

2, 7, 9, 10 (stops them being carboxylated)

21
Q

What are the indications for giving FFP

A
  1. Bleeding + abnormal coag test results (PT, APPT) - monitor response, clinically and by coagulation tests
  2. Reversal of warfarin (e.g. for urgent surgery - though not first line but given in emergency)
  3. Other conditions
22
Q

Describe cryoprecipitate

A
  1. Contains fibrinogen and f8 (and f1)
  2. Stored same as FFP = -30 for 2 yrs

Indications for use:

  1. If massive bleeding and low fibrinogen
  2. Rarely hypofibrinogenaemia
23
Q

Describe the use of platelets

A
  1. Stored at 22 degrees - room temp and constantly agitated
  2. Shelf life only 5 days
  3. NEED TO KNOW blood group - no cross match just choose same group. Can cause RhD sensitisation (as some red cell contamination)
24
Q

What are the indications to give platelets

A
  1. Mostly haematology patients with bone marrow failure (<10 x 10^9/l)
  2. Massive bleeding or acute DIC
  3. If very low platelets and patient needs surgery
  4. If for cardiac bypass and patient on anti-platelet drugs
  5. 1 pool usually enough
    (6. Generally - platelets and FFP overused - limited resource and cost)
25
Q

If prolonged PT and APPT - what do we give?

A

FFP - long PT/APPT indicate multiple coagulation factors not working

26
Q

F8 is given for?

A

VWF.

VWF improves circulation time of F8

27
Q

Fractionated products (large pool) of blood is heat treated, why?

A

Viral inactivation

28
Q

Which immunoglobulins are included in fractionated blood products?

A
  1. IM - specific - e.g. for tetanus, rabies, anti-D
  2. IM - normal globulin - broad mix in population (e.g. Hep A V)
  3. IVIg - pre-op in patients with ITP or AIHA
29
Q

When is albumin used?

A

4.5% albumin - used in burns, plasma exchanges, etc

20% albumin (Strong, salt poor) - used for certain severe liver and kidney conditions only

30
Q

Which infections must all blood be tested. for

A

Hep B, Hep c, HIV, HTLV, Syphilis, Hep E

Cannot rely only on testings

31
Q

All blood components have …. filtered out

A

WBC

Year 2 Collin (114 decks)

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