Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Year 2 - MCD - Haematology > Blood Transfusion > Flashcards

Blood Transfusion Flashcards

1
Q

Why is blood a scarce resource?

A
  • so far it cannot be synthesised
  • scarce resource because 1 donor can give about 1 pint every 4 months
  • need 9,000 units per day in the UK
  • can’t stockpile, blood shelf life is about 5w

-> use carefully

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

When would you give a patient a blood transfusion?

A
  • in major blood loss when fluids would not be enough
  • in anaemia when b12, folate or iron are not appropriate

-> Doctor’s decision

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Who discovered ABO blood groups?

A

Landsteiner 1901 (Nobel prize winner) - early human blood transfusions were fatal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What do genes that determine ABO group encode?

A
  • A gene codes for enzyme which adds N-acetyl galactosamine to common glycoprotein and fucose stem
  • B gene codes for enzyme which adds galactose
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Inheritance pattern of ABO genes

A
  • 0 is recessive

- A and B are co-dominant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the molecular structure of the different blood types?

A
  • O: only H stem
  • A: H stem with A sugar added onto it
  • B: H stem with B sugar (galactose) added onto it
  • AB: there are A and B
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the antibodies that cause adverse reactions when you are given the wrong blood type?

A
  • IgM antibodies, present from birth (=naturally occurring)
  • they fully activate the complement cascade and cause haemolysis of RBCs -> often fatal
  • You have the ones against the RBC antigen that you don’t have.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is the most and least common blood group in the UK?

A

Most: 0 (47%)
Least: AB (3%)

A has 42% and B has 8%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How do you check if you the donor matches the patients?

A
  • now usually done with machines
  • test with known anti-A and anti-B reagents
  • also x-match the donor’s blood with the pateints serum to check for agglutination
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What fraction of people are RhD positive/negative?

A

85% are positive

15% are negative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is an immunological difference between ABO and RhD antibodies?

A

the antibodies for ABO are naturally occurring (from birth) and make IgM pentamers.
People who lack the RhD antigen (ie: RhD negative) CAN make anti-D antibodies AFTER they are exposed to the RhD antigen - either by transfusion of RhD positive blood or in women, if they are pregnant with an RhD positive fetus
Anti-D antibodies are IgG antibodies. (-> can cross the placenta)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the reaction if you give the wring RhD?

A

Delayed haemolytic transfusion reaction because they are IgG type antibodies, they can’t activate the whole compliment system

  • There are AB coated RBCs, macrophages in the spleen attack them -> Hb can cause renal failure, you get jaundice etc
  • NOT IMMIDIATE FATAL REACTION LIKE WITH IgM !!!
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are implications of anti-D antibodies?

A
  1. Future transfusions
    - patient must, in future, have RhD neg blood (otherwise his anti-D would react with RhD pos blood - causes delayed haemolytic transfusion reaction - anaemia; high bilirubin; jaundice etc)
  2. HDN = haemolytic disease of the newborn
    - if RhD neg mother has anti-D - and in next pregnancy, fetus is RhD pos - mother’s IgG anti-D antibodies can cross placenta - causes haemolysis of fetal red cells - if severe: hydrops fetalis; death
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What fraction of donors actually have O neg?

A

6-7%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are some antigens aside from ABO and RhD?

A
  • Don’t routinely match blood for all these, eg Rh group -C, c, E, e; others - Kell, Duffy, Kidd, etc
  • About 8% of pts transfused will form Ab to one or more of these antigens
  • Once have formed antibody must use corresponding antigen negative blood; or else risk of delayed haemolytic reaction (can be severe)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How do we know if a patient will need antigen negative blood?

A

BEFORE each transfusion episode, test patient’s blood sample for red cell antibodies
Therefore, before transfusing patient, as well as testing their ABO and RhD group, must do an ‘antibody screen’ of their plasma

17
Q

What are blood components?

A
  • you no longer routinely give whole blood to patients

- you give components that they need

18
Q

Why do you no longer give whole blood to patients?

A 
- more efficient; less waste as patients don’t
need all the ‘components’; 
- some components degenerate quickly if 
stored as ‘whole blood’
- avoid fluid overload
19
Q

How is donor blood separated into different components?

A

Split one unit of blood by centrifuging whole bag (red cells bottom, platelets middle, plasma top) then squeeze each layer into satellite bags and cut free (closed system)

20
Q

Transfusion of RBCs

A
  • 1 unit from 1 donor - ‘packed cells’ (fluid plasma removed)
  • Shelf life 5 weeks; stored at 4oC (fridge)
  • Give through a ‘blood giving set’ - has filter to remove clumps/debris
  • Rarely need frozen red cells (National Frozen Bank) - for rare groups/ antibodies - poor recovery on thawing (lose 1/3 of the cells, only do this when there are strong indications)
21
Q

FFP

A

= fresh frozen plasma

  • 1 unit from 1 donor (300ml) can get small packs for children
  • Stored at -30oC (frozen within 6h of donation to preserve coag factors)
  • Shelf life 2 or now even 3 years
  • Must thaw approx 20-30 mins before use (if too hot, proteins cook)
  • Give ASAP – ideally within 1h or else coag factors degenerate at room temp
  • Dose 12-15ml/kg = usually 3 units
  • Need to know blood group - no x-match, just choose same group (as contains ABO antibodies, which could cause a bit of haemolysis
  • you can now leave it in the fridge for 1h (special indications only)
22
Q

What are indications for FFP?

A
  1. If bleeding + abnormal coag test results (PT, APTT)
    • Monitor response - clinically and by coag tests
  2. Reversal of warfarin (anticoagulant) eg for urgent surgery (if PCC not available)
  3. Other conditions occasionally

or if surgeons are about to make them bleed

NB not just to replace volume/ fluid loss

23
Q

What three main categories of products are won from a blood transfusion?

A
  1. RBCs
  2. Platelets
  3. Plasma (FFP, cryoprecipitate, plasma for fractionation (not in the UK) - albumin, factors etc)
24
Q

Cryoprecipitate?

A
  • From frozen plasma thawed at 4-8oC overnight residue remains
  • Contains fibrinogen and factor VIII
  • Same as FFP - store at -30oC for 2 yrs
  • Standard dose = from 10 donors (5 in a pack)

Indications:

  • If massive bleeding and fibrinogen very low
  • Rarely hypofibrinogenaemia
25
Q

Transfusion of platelets

A
  • 1 pool from 4 donors (= standard adult dose) or from 1 donor by apheresis (cell separator machine)
  • Store at 22oC (Room temp) - constantly agitated
  • Shelf life 5 days only - (risk of bacterial infection)
  • Need to know blood group (no x-match just choose same group (as platelets have low levels of ABO antigens on, so wrong group platelets would be destroyed quickly) - and can cause RhD sensitisation, as some red cell contamination)
  • can cause RhD sensitisation
26
Q

Indications for giving platelets?

A
  • Mostly haematology patients with bone marrow failure (if platelets <10 x 109/L)
  • Massive bleeding or acute DIC
  • If very low platelets and patient needs surgery
  • If for cardiac bypass and patient on anti-platelet drugs
  • 1 pool is usually enough - rarely need more
  • Generally, platelets and FFP overused in past - limited resource and cost
  • in chemotherapy patients that need platelets
  • in Cardiac bypass, chews up platelets. Don’t overuse it, gives patient transfusion reactions.
27
Q

If a patient is bleeding post surgery, what components does he need if:

a) His platelet count is normal and his coagulation test (PT and APTT) are prolonged?
b) His PT and APTT are long and his fibrinogen is low?

A
  • FFP -> does not need platelets. (needs numerous coag factors)
  • Cryoprecipitate (contains fibrinogen and factor 8) -> he would also need FFP
28
Q

When is fibrinogen particularly affected?

A

in Traumas

29
Q

What are some Fractionated Products (Large Pool)?

A
  • fractionated (like oil)
  • factor 8 and 9 (for haemophilia A and B respsectively, mainly in males)
  • immunoglobulins
  • albumin

UK plasma not allowed to make fractioned products. There is no spare blood, you have to do the other ones yourself. Fractioned products made from US plasma.

30
Q

Fractionated products - when are factors 8 and 9 given?

A
  • For haemophilia A and B respectively (males)
  • Factor VIII for von Willebrand’s disease
  • Heat treated - viral inactivation
  • Recombinant factor VIII or IX alternatives increasingly used, but expensive
31
Q

Fractionated products - when are immunoglobulins given?

A
  • IM: Specific - tetanus; anti-D; rabies
  • IM: Normal globulin - broad mix in population (eg: HAV)
  • IVIg – pre-op in patients with ITP or AIHA
32
Q

What is IVIg?

A
  • “soup” of antibodies in healthy peoples blood

- can help people that need Abs or in people with AI disease.

33
Q

Fractionated products - when is albumin given?

A
  • 4.5%
  • Useful in burns, plasma exchanges, etc
  • Probably overused (not indicated in malnutrition)
  • 20% (salt poor)
  • For certain severe liver and kidney conditions only
  • Useful in people who are losing a lot of water and proteins (e.g. burns)
  • In kidney/liver disease conditions.
34
Q

How do you keep the blood safe to the patient?

A
  • screen the donors blood for infections (not failsafe)
  • question them about easily behaviors
  • There is a window period between someone acquiring an infection and it being detectable by tests – you have to ask them about their behaviour as well.
  • use voluntary/unpaid donors
35
Q

What infections is blood tested for?

A 
Hepatitis B 	- HBsAg, PCR
Hepatitis C	- anti-HCV, PCR          
HIV		- anti-HIV, PCR
HTLV		- anti HTLV
Syphilis	- TPHA (spirochete)
Hepatitis E	- PCR
Some also tested for CMV (virus)

Malaria could also be transmitted, questionnaire excludes such individuals.

36
Q

How are donors protected?

A

Also aim to prevent harm to donors - by questioning them, to exclude risky ones (eg: people who have heart problems, etc)

37
Q

prion disease - vCJD

A
  • can be transmitted by blood transfusion
  • 4 cases where recipients had blood from donors who died from vCJD; 3 developed vCJD several years later
  • 1 had prion detected but asymptomatic & died of other cause
  • As precaution:
  • all plasma pooled to make fractionated products now obtained from USA (UK plasma - some used for FFP, the rest thrown away)
  • all blood components have white cells filtered out (leucodepleted) - in case white cells are essential for uptake of vCJD prion into brain to cause disease

Year 2 - MCD - Haematology (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions